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Tektronix 465 Scope
My Tek 465 scope has developed a minor but annoying fault in its
triggering circuitry but before diving into the guts of an old & faithful friend I would appreciate it if anyone who has experienced similar symptoms to those below could give me their thoughts on possible causes & (more importantly) how they fixed their particular version of the problem. 1) My scope just won't trigger in the A Normal mode although a stable trace obtained in A Auto will remain displayed (and stable) in A Normal until I touch either A Trigger slope or polarity controls. 2) I can stabilise a trace using the A Auto mode but only by adjusting the A Trigger Hold-off control rather than the A Trigger slope/polarity I would normally expect. 3) Everything appears to be triggering correctly when I use the B Trigger. 4) All other scope functions appear to be OK. I've checked these symptoms and they seem to be present what ever type of signal I'm inputting - sine/square, 1kHz - 1MHz, Ch1 or Ch2. I've got a set of battered circuit diagrams & layout drawings so should at least be able to follow up any ideas you experts might be able to pass my way. In the mean time many thanks for at least reading this posting and Merry Xmas & Happy New Year to everyone fra' Auld Reekie -- Dick GM0MNL |
"Dick" wrote
My Tek 465 scope has developed a minor but annoying fault in its triggering circuitry It sounds (reads) like a bad connection. By Ole Occam's razor, and a description of the problem - 'it works till I touch the knob' - my first guess is a dirty and/or worn synch selection switch or trigger level pot. The pot wouldn't happen to have one section for Ch. A and one for B and get bypassed in Auto, would it? If it were mine, I would first try a spritz of contact cleaner into the switch via the front panel slot (IIR465C). All contact cleaners are the same - mineral oil and alcohol - so the cheapest Radio Shack stuff works as well as anything. WD40 also works well. Getting to the switch or pot by disassembly I would save for last. There is an old adage "Fix anything long enough and you will _really_ break it." And I wish I would remember that adage in time. Other likely causes are bad connector, crimp or solder joint. After that electrolytic caps. -- Nicholas O. Lindan, Cleveland, Ohio Consulting Engineer: Electronics; Informatics; Photonics. Remove spaces etc. to reply: n o lindan at net com dot com psst.. want to buy an f-stop timer? nolindan.com/da/fstop/ OP: "Dick" wrote in message ... My Tek 465 scope has developed a minor but annoying fault in its triggering circuitry but before diving into the guts of an old & faithful friend I would appreciate it if anyone who has experienced similar symptoms to those below could give me their thoughts on possible causes & (more importantly) how they fixed their particular version of the problem. 1) My scope just won't trigger in the A Normal mode although a stable trace obtained in A Auto will remain displayed (and stable) in A Normal until I touch either A Trigger slope or polarity controls. 2) I can stabilise a trace using the A Auto mode but only by adjusting the A Trigger Hold-off control rather than the A Trigger slope/polarity I would normally expect. 3) Everything appears to be triggering correctly when I use the B Trigger. 4) All other scope functions appear to be OK. I've checked these symptoms and they seem to be present what ever type of signal I'm inputting - sine/square, 1kHz - 1MHz, Ch1 or Ch2. I've got a set of battered circuit diagrams & layout drawings so should at least be able to follow up any ideas you experts might be able to pass my way. In the mean time many thanks for at least reading this posting and Merry Xmas & Happy New Year to everyone fra' Auld Reekie -- Dick GM0MNL |
Dick wrote:
My Tek 465 scope has developed a minor but annoying fault in its triggering circuitry but before diving into the guts of an old & faithful friend I would appreciate it if anyone who has experienced similar symptoms to those below could give me their thoughts on possible causes & (more importantly) how they fixed their particular version of the problem. 1) My scope just won't trigger in the A Normal mode although a stable trace obtained in A Auto will remain displayed (and stable) in A Normal until I touch either A Trigger slope or polarity controls. 2) I can stabilise a trace using the A Auto mode but only by adjusting the A Trigger Hold-off control rather than the A Trigger slope/polarity I would normally expect. 3) Everything appears to be triggering correctly when I use the B Trigger. 4) All other scope functions appear to be OK. I've checked these symptoms and they seem to be present what ever type of signal I'm inputting - sine/square, 1kHz - 1MHz, Ch1 or Ch2. I've got a set of battered circuit diagrams & layout drawings so should at least be able to follow up any ideas you experts might be able to pass my way. In the mean time many thanks for at least reading this posting and Merry Xmas & Happy New Year to everyone fra' Auld Reekie -- Dick GM0MNL Clean the switches with Radio Shack tuner cleaner. -- Many thanks, Don Lancaster Synergetics 3860 West First Street Box 809 Thatcher, AZ 85552 voice: (928)428-4073 email: Please visit my GURU's LAIR web site at http://www.tinaja.com |
"Dick" wrote in message
... My Tek 465 scope has developed a minor but annoying fault in its triggering circuitry but before diving into the guts of an old & faithful friend I would appreciate it if anyone who has experienced similar symptoms to those below could give me their thoughts on possible causes & (more importantly) how they fixed their particular version of the problem. 1) My scope just won't trigger in the A Normal mode although a stable trace obtained in A Auto will remain displayed (and stable) in A Normal until I touch either A Trigger slope or polarity controls. 2) I can stabilise a trace using the A Auto mode but only by adjusting the A Trigger Hold-off control rather than the A Trigger slope/polarity I would normally expect. 3) Everything appears to be triggering correctly when I use the B Trigger. 4) All other scope functions appear to be OK. I've checked these symptoms and they seem to be present what ever type of signal I'm inputting - sine/square, 1kHz - 1MHz, Ch1 or Ch2. I've got a set of battered circuit diagrams & layout drawings so should at least be able to follow up any ideas you experts might be able to pass my way. You need the Tekscopes group: Leon |
"Nicholas O. Lindan" schreef in bericht
nk.net... [snip] Getting to the switch or pot by disassembly I would save for last. There is an old adage "Fix anything long enough and you will _really_ break it." And I wish I would remember that adage in time. How true. Today I fixed something... all the way to the rubbish bin ;) -- Thanks, Frank. (remove 'q' and 'invalid' when replying by email) |
If it were mine, I would first try a spritz of contact cleaner into the switch via the front panel slot (IIR465C). All contact cleaners are the same - mineral oil and alcohol - so the cheapest Radio Shack stuff works as well as anything. WD40 also works well. ============================== On various occsasions I have been told that WD40 is NOT the right cleaning agent for electrical systems involving plastic insulation re wiring, etc. I always use (non chlorinated) contact cleaner as available from Rat Shack and similar stores. Here in the UK I use contact cleaner supplied by Maplin. Frank GM0CSZ / KN6WH |
Dick wrote:
My Tek 465 scope has developed a minor but annoying fault in its triggering circuitry but before diving into the guts of an old & faithful friend I would appreciate it if anyone who has experienced similar symptoms to those below could give me their thoughts on possible causes & (more importantly) how they fixed their particular version of the problem. 1) My scope just won't trigger in the A Normal mode although a stable trace obtained in A Auto will remain displayed (and stable) in A Normal until I touch either A Trigger slope or polarity controls. 2) I can stabilise a trace using the A Auto mode but only by adjusting the A Trigger Hold-off control rather than the A Trigger slope/polarity I would normally expect. 3) Everything appears to be triggering correctly when I use the B Trigger. 4) All other scope functions appear to be OK. I've checked these symptoms and they seem to be present what ever type of signal I'm inputting - sine/square, 1kHz - 1MHz, Ch1 or Ch2. I've got a set of battered circuit diagrams & layout drawings so should at least be able to follow up any ideas you experts might be able to pass my way. In the mean time many thanks for at least reading this posting and Merry Xmas & Happy New Year to everyone fra' Auld Reekie Have you cleaned the controls and switches? Electromechanical parts are the weakest link. -- Joe Legris |
In article et,
Nicholas O. Lindan wrote: By Ole Occam's razor, and a description of the problem - 'it works till I touch the knob' - my first guess is a dirty and/or worn synch selection switch or trigger level pot. The pot wouldn't happen to have one section for Ch. A and one for B and get bypassed in Auto, would it? If it were mine, I would first try a spritz of contact cleaner into the switch via the front panel slot (IIR465C). All contact cleaners are the same - mineral oil and alcohol - so the cheapest Radio Shack stuff works as well as anything. WD40 also works well. Ugh. and Ugh again. I'd raise three cautions about this advice: [1] My recollection is that Tek specifically warns against using most contact cleaners on, or around, certain of the internal controls (e.g. the attenuator switches). These switches are apparently quite sensitive to contamination, as they deal with high-impedance signals. Spraying an oil-and-alcohol contact cleaner anywhere in their area might very well contaminate them. IIRC, Tek's recommendation is to use pure isopropyl alcohol, and a small clean brush, for cleaning contacts. [2] Not all contact cleaners are the same. Many used for sensitive equipment are "zero-residue" types - they have a cleaning solvent and propellant, but do not contain any sort of lubricant, and are intended to leave nothing behind on the contacts. Even among the contact treatments which do contain a lubricant of some sort, there is wide variation in the type of solvent used (some use alcohol, some use a hydrocarbon or chlorinated/fluorinated hydrocarbon) and the lubricant used (some use mineral oil, some a polyphenyl ether, others something else entirely). It pays to use the right combination for the job. [3] I would not use WD-40 as a contact cleaner, on anything less robust than an electric motor. It's not formulated for that purpose (in fact, it's not really formulated as a long-term lubricant!) and it is notorious for getting gummy and attracting dust over the long run. -- Dave Platt AE6EO Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior I do _not_ wish to receive unsolicited commercial email, and I will boycott any company which has the gall to send me such ads! |
"Dick" schreef in bericht ... My Tek 465 scope has developed a minor but annoying fault in its triggering circuitry but before diving into the guts of an old & faithful friend I would appreciate it if anyone who has experienced similar symptoms to those below could give me their thoughts on possible causes & (more importantly) how they fixed their particular version of the problem. 1) My scope just won't trigger in the A Normal mode although a stable trace obtained in A Auto will remain displayed (and stable) in A Normal until I touch either A Trigger slope or polarity controls. 2) I can stabilise a trace using the A Auto mode but only by adjusting the A Trigger Hold-off control rather than the A Trigger slope/polarity I would normally expect. 3) Everything appears to be triggering correctly when I use the B Trigger. 4) All other scope functions appear to be OK. I've checked these symptoms and they seem to be present what ever type of signal I'm inputting - sine/square, 1kHz - 1MHz, Ch1 or Ch2. I've got a set of battered circuit diagrams & layout drawings so should at least be able to follow up any ideas you experts might be able to pass my way. In the mean time many thanks for at least reading this posting and Merry Xmas & Happy New Year to everyone fra' Auld Reekie -- Dick GM0MNL At the moment I'm having a fight with my Dynatek. So I looked up this section in the schematics. Triggering looks simple. The trigger signal is enabled/disabled by the outputs of a flipflop (LS74 here) which is set/cleared by the channel selector switch. Here the switch is floating to select Channel 2. So a bad contact will select channel 2. It looks almost too simple, but an attack with contact cleaner may cure your old friend. Carel |
A number of the switches on the 465 use PC board pads as contacts. They
have heavy gold plating, but eventually the gold wears off. When that happens, the switch is dead and as far as I know can't be repaired. You might be able to squeeze a little more life out of it by cleaning, but in any case I'd be very careful not to use a cleaner with any abrasive qualities. If cleaning doesn't cure the problem, worn pads might be the cause. But by all means check with the 'scope newsgroup. I'm sure you'll find folks who have had a lot of experience with the 465, and some might even know of some kind of fix or replacement for worn switch contact pads. Roy Lewallen, W7EL |
"Highland Ham" wrote in
: If it were mine, I would first try a spritz of contact cleaner into the switch via the front panel slot (IIR465C). All contact cleaners are the same - mineral oil and alcohol - so the cheapest Radio Shack stuff works as well as anything. WD40 also works well. ============================== On various occsasions I have been told that WD40 is NOT the right cleaning agent for electrical systems involving plastic insulation re wiring, etc. I always use (non chlorinated) contact cleaner as available from Rat Shack and similar stores. Here in the UK I use contact cleaner supplied by Maplin. Frank GM0CSZ / KN6WH On TEK LF or HF cam style contact switches,do NOT use mineral oil-based cleaner/lubes.Take some 99% isopropyl alco,wet a narrow paper strip,and slide under the closed contact,and move back and forth.These cam-style switches have VERY low wiping force,and any oil,grease,or film will cause intermittents or opens. I suspect a calibration may improve his triggering,too. -- Jim Yanik jyanik-at-kua.net |
Don Lancaster wrote in :
Clean the switches with Radio Shack tuner cleaner. No.Use 99% isopropyl alcohol. -- Jim Yanik jyanik-at-kua.net |
In article ,
. says... Don Lancaster wrote in : Clean the switches with Radio Shack tuner cleaner. No.Use 99% isopropyl alcohol. You know, it's funny how often these debates flare up over a subject as mundane as contact cleaner. "My tuner cleaner is better than your tuner cleaner. Your tuner cleaner should be used only in Ukrainian opposition candidates' minestrone. My tuner cleaner costs more than HP printer ink. If you spray your tuner cleaner on a Tektronix 465, it will trigger a resonance cascade and gate in alien overlords from the planet Xen." Yadda, yadda, yadda. Despite all the gurus out there forking the evil eye at WD-40, I sure seem to own a lot of stuff that still works fine after being sprayed with WD-40 over the years (decades, in some cases). Yeah, I know. "Data: n, plural of 'anecdote'." Some of these gurus are admittedly respected veterans of companies such as Tektronix, with whom mere mortals are loath to argue. All I can say is, those switches must not have been of the greatest quality in the first place, or the gurus wouldn't have to spend so much of their time on Usenet warning people against hosing them down with WD-40. Just sayin', is all. No disrespect intended. :) -- jm ------------------------------------------------------ http://www.qsl.net/ke5fx Note: My E-mail address has been altered to avoid spam ------------------------------------------------------ |
"John Miles" schreef in bericht
... [snip] Some of these gurus are admittedly respected veterans of companies such as Tektronix, with whom mere mortals are loath to argue. All I can say is, those switches must not have been of the greatest quality in the first place, or the gurus wouldn't have to spend so much of their time on Usenet warning people against hosing them down with WD-40. LOL. Well, some switches on oscilloscopes are very fragile with many, many contacts, and rather low contact pressure. Sometimes hermetically sealed too, so you can even use a spray can of Spam or shaving foam and it won't hurt a bit ;) -- Thanks, Frank. (remove 'q' and 'invalid' when replying by email) |
The discussion about contact cleaner isn't altogether mundane.
I worked at Tek for many years, although I'm certainly not a guru when it comes to oscilloscope maintenance. But I do recall one experience with cleaning solvents and board-mounted switches. Before introducing a new instrument, we went through a lengthy process of building and testing prototypes, which I described some time ago in this newsgroup. In one group, it was our practice to borrow some assemblers from production to build the prototypes. One afternoon I was looking at some units they had built, after they had left for the day, and saw that the plastic of some switch bodies was very badly crazed -- they were covered with tiny cracks. Some experiments with bottles of solvent we found in some of the assemblers' work areas pinned it down to one particular liquid. The problem was one of the ingredients, which was a relatively common solvent of the time. Unfortunately, I don't recall which one -- it was something pretty mild as solvents go, like toluene or Freon, not a relatively strong solvent like acetone, which we all knew better than to use. We found out that the solvent had been banned from production, but the assemblers kept a supply out of sight because it was really good at removing flux. The lesson is that even some normally pretty innocent solvents can destroy some plastics. Other components can also be ruined by various solvents, so that's another reason to use some caution. As just one example, it was found that Freon and its relatives would migrate up the leads and into even pretty well sealed radial leaded aluminum electrolytic capacitors, corroding the insides and causing premature failure. This was solved by improving the end seals, but only after a lot of the older type reached the field, some on boards having been washed with Freon. Of course, Freon is no longer used, but there are a host of other potential problems. It's ultimately up to you to decide whether you want to experiment with your scope. As for WD-40, I love the stuff and use it on all kinds of switches and electrical components. But I mentioned a short while ago that the cam switches in the 465 and some other scopes use PC board pads for contacts, and when the pad's gold plating is gone, the switch -- and the scope -- is dead. So it doesn't seem like a good thing to me to use a cleaner on those that'll leave a film which can collect dust or anything abrasive. I don't agree that a switch's ability to withstand WD-40 or any other particular chemical is an indicator of its quality. But we all have our own criteria we use to judge. Roy Lewallen, W7EL John Miles wrote: You know, it's funny how often these debates flare up over a subject as mundane as contact cleaner. "My tuner cleaner is better than your tuner cleaner. Your tuner cleaner should be used only in Ukrainian opposition candidates' minestrone. My tuner cleaner costs more than HP printer ink. If you spray your tuner cleaner on a Tektronix 465, it will trigger a resonance cascade and gate in alien overlords from the planet Xen." Yadda, yadda, yadda. Despite all the gurus out there forking the evil eye at WD-40, I sure seem to own a lot of stuff that still works fine after being sprayed with WD-40 over the years (decades, in some cases). Yeah, I know. "Data: n, plural of 'anecdote'." Some of these gurus are admittedly respected veterans of companies such as Tektronix, with whom mere mortals are loath to argue. All I can say is, those switches must not have been of the greatest quality in the first place, or the gurus wouldn't have to spend so much of their time on Usenet warning people against hosing them down with WD-40. Just sayin', is all. No disrespect intended. :) -- jm ------------------------------------------------------ http://www.qsl.net/ke5fx Note: My E-mail address has been altered to avoid spam ------------------------------------------------------ |
"Highland Ham" wrote
WD40 is NOT the right cleaning agent for electrical systems involving plastic insulation re wiring, etc. That was also my impression. But I have used it on plastics and have not found any problems after 20 years. Famous last words, I know. I have used it as a contact cleaner with great success. -- Nicholas O. Lindan, Cleveland, Ohio Consulting Engineer: Electronics; Informatics; Photonics. Remove spaces etc. to reply: n o lindan at net com dot com psst.. want to buy an f-stop timer? nolindan.com/da/fstop/ |
"Roy Lewallen" wrote
cam switches in the 465 and some other scopes use PC board pads for contacts, and when the pad's gold plating is gone, the switch -- and the scope -- is dead. It is possible to re-plate the gold. But imagining the circuit board it may be impossible to mask the components. Aw, what the heck - gold plate the whole thing and screw it to your Hinkley yacht. -- Nicholas O. Lindan, Cleveland, Ohio Consulting Engineer: Electronics; Informatics; Photonics. Remove spaces etc. to reply: n o lindan at net com dot com psst.. want to buy an f-stop timer? nolindan.com/da/fstop/ |
John Miles wrote in
: Some of these gurus are admittedly respected veterans of companies such as Tektronix, with whom mere mortals are loath to argue. I worked for TEK for 21.5 years as a service tech in 2 of their field offices;repaired and cal'd a lot of scopes and other TEK products. All I can say is, those switches must not have been of the greatest quality in the first place, or the gurus wouldn't have to spend so much of their time on Usenet warning people against hosing them down with WD-40. Considering how longlasting and popular the 465 is,that's not a very smart sentence.The same HF and LF cam switches were also used in the high- performance 7000 series lab scopes. Just sayin', is all. No disrespect intended. :) -- jm Same here. -- Jim Yanik jyanik-at-kua.net |
If there's any disagreement between what I say and what Jim says about
maintaining Tek scopes, listen to Jim and not me. He was there in the trenches; I wasn't. Roy Lewallen, W7EL Jim Yanik wrote: I worked for TEK for 21.5 years as a service tech in 2 of their field offices;repaired and cal'd a lot of scopes and other TEK products. . . . |
I recently gave away a 465 that was giving me fits. I don't know what
happened to it, but it had squirrelly problems all over. It was shipped to Tek for repair in the early 1990's and Tek said it was unrepairable. Of course I knew better....... It was used extensively in field service, and was probably vibrated to death, but it had the damndest problems I ever saw. The ones that really killed me (other than the vertical attenuator switches) were an oscillation in the Ch 1 vertical, inability to get a smooth leading edge on a fast rise (fall was OK) and an intermittently failing intensified sweep. I spent about 100 hours on that thing and never did get it to work right. I don't know if that had multi-layer boards or not, but it acted like some inaccessible connections were intermittent. I checked and changed component after component, and there would always be one more trouble. That was my weekend for a few months; I would start and go througn the WHOLE calibration procedure (including the stuff that everybody skips, like swinging the line to check the power supply at high and low line conditions) to see how far I could get this time. Undoubtedly I would stop at some point because the adjustment didn't have enough range or some such. I'd fix that and next week a different set of stuff wouldn't work. The problems were never expensive stuff, just resistors and capacitors. That was the ONLY Tek scope that ever stumped me. I even managed to keep a 647 running, and those NEVER worked. Yes indeed. The perversity of the inanimate. So I gave away the 465 and bought a TDS2012. Took a little getting used to, but I've never looked back. Still have the old reliable 547 and a whole slew of plug-ins in the corner, but they are going to need a new home before too long. "Roy Lewallen" wrote in message ... If there's any disagreement between what I say and what Jim says about maintaining Tek scopes, listen to Jim and not me. He was there in the trenches; I wasn't. Roy Lewallen, W7EL Jim Yanik wrote: I worked for TEK for 21.5 years as a service tech in 2 of their field offices;repaired and cal'd a lot of scopes and other TEK products. . . . |
On Wed, 22 Dec 2004 14:55:03 -0500, BFoelsch wrote:
So I gave away the 465 and bought a TDS2012. Took a little getting used to, but I've never looked back. Still have the old reliable 547 and a whole slew of plug-ins in the corner, but they are going to need a new home before too long. Tek won't fix the 2012 either :( |
"Bob Stephens" wrote in message .. . On Wed, 22 Dec 2004 14:55:03 -0500, BFoelsch wrote: So I gave away the 465 and bought a TDS2012. Took a little getting used to, but I've never looked back. Still have the old reliable 547 and a whole slew of plug-ins in the corner, but they are going to need a new home before too long. Tek won't fix the 2012 either :( Well, it did come with a three year warranty, and it does work well right now, which is more than the 465 did. But I hear you. Time will tell. |
"BFoelsch" wrote in
: I recently gave away a 465 that was giving me fits. I don't know what happened to it, but it had squirrelly problems all over. It was shipped to Tek for repair in the early 1990's and Tek said it was unrepairable. Of course I knew better....... It was used extensively in field service, and was probably vibrated to death, but it had the damndest problems I ever saw. The ones that really killed me (other than the vertical attenuator switches) were an oscillation in the Ch 1 vertical, inability to get a smooth leading edge on a fast rise (fall was OK) and an intermittently failing intensified sweep. I spent about 100 hours on that thing and never did get it to work right. I don't know if that had multi-layer boards or not, but it acted like some inaccessible connections were intermittent. I checked and changed component after component, and there would always be one more trouble. That was my weekend for a few months; I would start and go througn the WHOLE calibration procedure (including the stuff that everybody skips, like swinging the line to check the power supply at high and low line conditions) to see how far I could get this time. Undoubtedly I would stop at some point because the adjustment didn't have enough range or some such. I'd fix that and next week a different set of stuff wouldn't work. The problems were never expensive stuff, just resistors and capacitors. That was the ONLY Tek scope that ever stumped me. I even managed to keep a 647 running, and those NEVER worked. Yes indeed. The perversity of the inanimate. So I gave away the 465 and bought a TDS2012. Took a little getting used to, but I've never looked back. Still have the old reliable 547 and a whole slew of plug-ins in the corner, but they are going to need a new home before too long. Trying to support a TEK product without the Tek selected transistors and other specialized components is extremely difficult. One of the first things I did when getting a unit that someone else had tried to repair was to find and remove all the non-Tek xstrs,and replace with the proper TEK parts.They were often causes of oscillations and bad HF responses.Some scopes may have had ferrite beads used in some places lost or not installed with the new transistors.One other common problem was a black silver oxide growing on the tiny HF trimmer caps,especially on the bottom of them,acting as an insulator and making the cap open and ineffective. IMO,the HF cam contacts used in the attenuators should be failing and no longer repairable due to the plastic part that holds the gold contact to the spring metal degrading and coming apart,or loss of spring tension. That's a problem with using plastic parts,they outgass and eventually degrade and lose strength.Some of the atten intermittents can be due to the outgassing making a film on the contacts and pads. -- Jim Yanik jyanik-at-kua.net |
Bob Stephens wrote in
: On Wed, 22 Dec 2004 14:55:03 -0500, BFoelsch wrote: So I gave away the 465 and bought a TDS2012. Took a little getting used to, but I've never looked back. Still have the old reliable 547 and a whole slew of plug-ins in the corner, but they are going to need a new home before too long. Tek won't fix the 2012 either :( TEK has a Long Term Product Support(LTPS) policy,where the item will be serviceable by TEK X number of years after it's last sold in their catalog. They have a list of whats supported and for how long on their website,IIRC. "X" used to be 9 years,then got cut to 6,then some items are only ONE year. That's why you have to check the list. Also,repair prices climb in the last couple of years of "support",to encourage you to buy a new unit. AFTER the LTPS period is over,the item is no longer supported at all. No exchange modules,and no parts support unless the part is used in a current product. -- Jim Yanik jyanik-at-kua.net |
"Jim Yanik" . wrote in message .. . "BFoelsch" wrote in : I recently gave away a 465 that was giving me fits. I don't know what happened to it, but it had squirrelly problems all over. It was shipped to Tek for repair in the early 1990's and Tek said it was unrepairable. Of course I knew better....... It was used extensively in field service, and was probably vibrated to death, but it had the damndest problems I ever saw. The ones that really killed me (other than the vertical attenuator switches) were an oscillation in the Ch 1 vertical, inability to get a smooth leading edge on a fast rise (fall was OK) and an intermittently failing intensified sweep. I spent about 100 hours on that thing and never did get it to work right. I don't know if that had multi-layer boards or not, but it acted like some inaccessible connections were intermittent. I checked and changed component after component, and there would always be one more trouble. That was my weekend for a few months; I would start and go througn the WHOLE calibration procedure (including the stuff that everybody skips, like swinging the line to check the power supply at high and low line conditions) to see how far I could get this time. Undoubtedly I would stop at some point because the adjustment didn't have enough range or some such. I'd fix that and next week a different set of stuff wouldn't work. The problems were never expensive stuff, just resistors and capacitors. That was the ONLY Tek scope that ever stumped me. I even managed to keep a 647 running, and those NEVER worked. Yes indeed. The perversity of the inanimate. So I gave away the 465 and bought a TDS2012. Took a little getting used to, but I've never looked back. Still have the old reliable 547 and a whole slew of plug-ins in the corner, but they are going to need a new home before too long. Trying to support a TEK product without the Tek selected transistors and other specialized components is extremely difficult. One of the first things I did when getting a unit that someone else had tried to repair was to find and remove all the non-Tek xstrs,and replace with the proper TEK parts.They were often causes of oscillations and bad HF responses.Some scopes may have had ferrite beads used in some places lost or not installed with the new transistors.One other common problem was a black silver oxide growing on the tiny HF trimmer caps,especially on the bottom of them,acting as an insulator and making the cap open and ineffective. IMO,the HF cam contacts used in the attenuators should be failing and no longer repairable due to the plastic part that holds the gold contact to the spring metal degrading and coming apart,or loss of spring tension. That's a problem with using plastic parts,they outgass and eventually degrade and lose strength.Some of the atten intermittents can be due to the outgassing making a film on the contacts and pads. Yes, this unit could indeed have had some non-Tek semiconductors in it. I got the HF ocsillation to stop by putting a few gimmick capacitors, less that 1 pF, at the output of the Ch 1 vertical amp. Didn't affect the frequency response any, but the vertical output amp had a few extra time constants visible on a leading edge that none of the adjustments would control. It was a real learning experience, but the patient died. One thing I DID learn was that gold-plated sockets don't mean a thing if they mate with tinned leads. When I first got that scope almost nothing worked, and major recovery was effected by removing and replacing all the socketed connectiions, which in that scope included virtually all of the semiconductors. I also suspected that that scope was not a "complete" instrument; seems to me that the versions and serial numbers didn't really agree, as if someone tried to make one good scope out of parts from other ones that were of varying vintages. Anyway, I decided that I am out of the scope-fixing business. It's kind of like changing the engine in a car, the first couple dozen are fun, and after that its just plain work. -- Jim Yanik jyanik-at-kua.net |
On Wed, 22 Dec 2004 05:15:23 -0800, Roy Lewallen wrote:
(snip) Before introducing a new instrument, we went through a lengthy process of building and testing prototypes, which I described some time ago in this newsgroup. In one group, it was our practice to borrow some assemblers from production to build the prototypes. One afternoon I was looking at some units they had built, after they had left for the day, and saw that the plastic of some switch bodies was very badly crazed -- they were covered with tiny cracks. Some experiments with bottles of solvent we found in some of the assemblers' work areas pinned it down to one particular liquid. The problem was one of the ingredients, which was a relatively common solvent of the time. Unfortunately, I don't recall which one -- it was something pretty mild as solvents go, like toluene or Freon, not a relatively strong solvent like acetone, which we all knew better than to use. We found out that the solvent had been banned from production, but the assemblers kept a supply out of sight because it was really good at removing flux. May well have been toluene. It was often used as a cleaner in all sorts of areas, some as pedestrian as the T/R/S plugs on old lamp-signalling telephone switchboards. Unfortunately proved to be a carcinogen and was banned, but it WAS used to clean a myriad of hardware in a myriad of situations. |
budgie wrote: (snip) May well have been toluene. It was often used as a cleaner in all sorts of areas, some as pedestrian as the T/R/S plugs on old lamp-signalling telephone switchboards. Unfortunately proved to be a carcinogen and was banned, but it WAS used to clean a myriad of hardware in a myriad of situations. Banned? Perhaps from use as a general solvent in assembly areas, but if you walk into most hardware stores (such as Ace), you can buy it in gallons in their paint sections... Pretty cheap too! It's at least a bit amazing that one industry may ban an item, yet another still provides it... It seems that you can't purchase lacquer paint for an automobile anywhere at this point, yet can still buy gallons of lacquer thinner (and lacquer based paints for wood) at the local hardware store... sigh... --Rick AH7H |
In article ,
. says... Considering how longlasting and popular the 465 is,that's not a very smart sentence.The same HF and LF cam switches were also used in the high- performance 7000 series lab scopes. True enough in the case of the 465. That model in particular seems to have been very robust. You don't see many owners asking about how to clean 465 switches. 485 switches, though, are another thing entirely. It's very rare to see a 485 whose vertical attenuator switches aren't noisy. Perhaps gold-pad abrasion has caught up to the instruments over time; however, I'm personally aware of at least two anecdotal cases of noisy 485 switches being fixed (at least for the time being) with contact cleaner. It's possible there's more than one cause of switch degradation at work in the 485 and other notorious "problem children." Either way, though, the original designers were clearly not omniscient in all cases, or the problems with certain models wouldn't be as widespread as they are. I wish there were a sure-fire way to fix the 485's front-end switches; it was my favorite Tek scope of the bunch otherwise. -- jm ------------------------------------------------------ http://www.qsl.net/ke5fx Note: My E-mail address has been altered to avoid spam ------------------------------------------------------ |
I read in sci.electronics.design that budgie wrote (in
) about 'Tektronix 465 Scope', on Thu, 23 Dec 2004: May well have been toluene. It was often used as a cleaner in all sorts of areas, some as pedestrian as the T/R/S plugs on old lamp-signalling telephone switchboards. Unfortunately proved to be a carcinogen and was banned, but it WAS used to clean a myriad of hardware in a myriad of situations. Toluene is one of the aromatics that is NOT carcinogenic. From the ATSDR web site: QUOTE Studies in workers and animals exposed to toluene generally indicate that toluene does not cause cancer. The International Agency for Research on Cancer (IARC) and the Department of Health and Human Services (DHHS) have not classified toluene for carcinogenic effects. The EPA has determined that toluene is not classifiable as to its human carcinogenicity. ENDQUOTE Toluene is available in small quantities as a solvent for contact adhesive. It DOES attack some plastics, and those it attacks slowly can exhibit surface dulling and crazing. -- Regards, John Woodgate, OOO - Own Opinions Only. The good news is that nothing is compulsory. The bad news is that everything is prohibited. http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk |
May well have been toluene. It was often used as a cleaner in all sorts
of areas, some as pedestrian as the T/R/S plugs on old lamp-signalling telephone switchboards. Unfortunately proved to be a carcinogen and was banned, but it WAS used to clean a myriad of hardware in a myriad of situations. It might have been carbon tet (tetracloride or however it is spelled). I think it was taken off the market because of either liver or kidney failure if the user had been drinking . |
Other than speed, is there any difference between a 465B and a 475/475A that I should know about? I am looking for a replacement but I want all or nearly all of the knobs to be the same. |
Ralph Mowery wrote:
May well have been toluene. It was often used as a cleaner in all sorts of areas, some as pedestrian as the T/R/S plugs on old lamp-signalling telephone switchboards. Unfortunately proved to be a carcinogen and was banned, but it WAS used to clean a myriad of hardware in a myriad of situations. It might have been carbon tet (tetracloride or however it is spelled). I think it was taken off the market because of either liver or kidney failure if the user had been drinking . When carbon tet was removed from telephone offices there was a story about a technician spilling some on a operator. The operator lost here hair and finger nails. Don't know if that is true but we had to remove all carbon tet from the cleaning supplies. Bill K7NOM |
John Miles wrote in
: In article , . says... Considering how longlasting and popular the 465 is,that's not a very smart sentence.The same HF and LF cam switches were also used in the high- performance 7000 series lab scopes. True enough in the case of the 465. That model in particular seems to have been very robust. You don't see many owners asking about how to clean 465 switches. 485 switches, though, are another thing entirely. It's very rare to see a 485 whose vertical attenuator switches aren't noisy. Perhaps gold-pad abrasion has caught up to the instruments over time; however, I'm personally aware of at least two anecdotal cases of noisy 485 switches being fixed (at least for the time being) with contact cleaner. It's possible there's more than one cause of switch degradation at work in the 485 and other notorious "problem children." Either way, though, the original designers were clearly not omniscient in all cases, or the problems with certain models wouldn't be as widespread as they are. I wish there were a sure-fire way to fix the 485's front-end switches; it was my favorite Tek scope of the bunch otherwise. -- jm Both 465 and 485 use the same HF cam switch contacts. TEK used to have a repair kit that included both contacts,drill bits to remove the securing rivets,and tiny nuts and bolts to secure the new contacts. They also had a repair kit for the LF contacts used in the timing switch,with an alignment guide to get them straight. Both are no longer available. -- Jim Yanik jyanik-at-kua.net |
On Thu, 23 Dec 2004 16:44:05 +0000, Bill Janssen wrote:
Ralph Mowery wrote: It might have been carbon tet (tetracloride or however it is spelled). I think it was taken off the market because of either liver or kidney failure if the user had been drinking . When carbon tet was removed from telephone offices there was a story about a technician spilling some on a operator. The operator lost here hair and finger nails. This is so stupid it's ludicrous. Don't know if that is true but we had to remove all carbon tet from the cleaning supplies. That's typical government wisdumb for you. Make laws based on hysteria. Cheers! Rich |
On Thu, 23 Dec 2004 08:20:30 +0000, John Woodgate wrote:
I read in sci.electronics.design that budgie wrote (in ) about 'Tektronix 465 Scope', on Thu, 23 Dec 2004: May well have been toluene. It was often used as a cleaner in all sorts of areas, some as pedestrian as the T/R/S plugs on old lamp-signalling telephone switchboards. Unfortunately proved to be a carcinogen and was banned, but it WAS used to clean a myriad of hardware in a myriad of situations. Toluene is one of the aromatics that is NOT carcinogenic. From the ATSDR web site: QUOTE Studies in workers and animals exposed to toluene generally indicate that toluene does not cause cancer. The International Agency for Research on Cancer (IARC) and the Department of Health and Human Services (DHHS) have not classified toluene for carcinogenic effects. The EPA has determined that toluene is not classifiable as to its human carcinogenicity. ENDQUOTE Toluene is available in small quantities as a solvent for contact adhesive. It DOES attack some plastics, and those it attacks slowly can exhibit surface dulling and crazing. They banned it because it was the "active ingredient" in airplane glue, which kids sniffed and got high. Cheers! Rich |
Rich Grise wrote:
. . . That's typical government wisdumb for you. Make laws based on hysteria. Cheers! Rich Yeah, that's the stoopid guv'mint for ya! If they was just as smart as we was, they wouldn't ban all this neat stuff. According to a hazmat data sheet I have, carbon tet (which can be absorbed by breathing, skin contact, or ingestion) causes damage to the liver, kidneys, heart, adrenal glands, and nervous system, and is particularly dangerous to people who have recently consumed alcohol, are exceedingly fleshy or are undernourished, or have other problems like hypertension. You can smell it at a concentration of 70 ppm; toxicity is known at concentrations of 5 ppm. I used the stuff quite a bit when I was a kid, and I'm just fine (I think) so that's obvious proof that it's all a bunch of hogwash and a government conspiracy. Personally, I favor allowing anyone to buy and sell any kind of hazardous chemical or object. By banning them, we've interfered with natural selection, which seems to be resulting in a less and less intelligent population. A sort of "unintelligent design" as it were. Roy Lewallen, W7EL |
On Thu, 23 Dec 2004 05:09:21 GMT, Rick Frazier wrote:
budgie wrote: (snip) May well have been toluene. It was often used as a cleaner in all sorts of areas, some as pedestrian as the T/R/S plugs on old lamp-signalling telephone switchboards. Unfortunately proved to be a carcinogen and was banned, but it WAS used to clean a myriad of hardware in a myriad of situations. Banned? Perhaps from use as a general solvent in assembly areas, but if you walk into most hardware stores (such as Ace), you can buy it in gallons in their paint sections... Pretty cheap too! Different countries, different strokes. |
On Thu, 23 Dec 2004 08:20:30 +0000, John Woodgate
wrote: I read in sci.electronics.design that budgie wrote (in ) about 'Tektronix 465 Scope', on Thu, 23 Dec 2004: May well have been toluene. It was often used as a cleaner in all sorts of areas, some as pedestrian as the T/R/S plugs on old lamp-signalling telephone switchboards. Unfortunately proved to be a carcinogen and was banned, but it WAS used to clean a myriad of hardware in a myriad of situations. Toluene is one of the aromatics that is NOT carcinogenic. From the ATSDR web site: (snip) That was the reason used when it was banned here, merit notwithstanding. |
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