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Sending power into rig unused for 30 years : Precautions ?
Now retired I'm trying to become active again.
My TS-520S has not been on for 30 years. I don't have a variactor ( variable transformer ). At the TARC advice was to put a lightbulb in series to take the surge. Should I use a high resistance ( low wattage ) bulb or vice versa ? Would this be as good as a simple L-C network ? Somebody said just plug it in. Are there any other ideas ? Thanks for your kind assistance. Dave WB3DWE Temple, TX |
Sending power into rig unused for 30 years : Precautions ?
Now retired I'm trying to become active again.
My TS-520S has not been on for 30 years. I don't have a variactor ( variable transformer ). I'd strongly encourage you to ask around, find somebody who has one, and do the power-up with the variable-voltage transformer. Take your time - ease the voltage up from zerch to nominal over a period of a few minutes. At the TARC advice was to put a lightbulb in series to take the surge. Should I use a high resistance ( low wattage ) bulb or vice versa ? If you do this, do the former... low-wattage. You want to power up the rig *slowly*, so that the dielectrics in the electrolytic capacitors have a chance to re-form gently. The lower the wattage of the bulb (the higher the resistance) the longer it'll take to charge the power supply fully and the lower the final voltage will be. You could do it in stages. Wire up a standard light-bulb socket in series with a power cord for the rig. Start out with a 5-watt bulb, power up, let the rig sit for a few minutes, power down again, switch to a 25-watt bulb, repeat the process again... then go to a 100-watt bulb, then a 200-watt bulb. This approach isn't as effective, or as controllable, as using a Variac or similar variable-voltage transformer. The bulb's resistance will be low when it's cold, and will rise when it heats up... so it won't limit the initial inrush current all that effectively. Would this be as good as a simple L-C network ? Somebody said just plug it in. It might easily go BOOM if you do. If it's been sitting around un-powered for 30 years, the dielectic oxide layer in the power supply caps may have thinned and developed pinholes... hitting it with full mains voltage and no current limiting could result in a sudden short circuit inside the caps. They're quite spectacular when they blow... messy, though. Are there any other ideas ? Negative-temperature-coefficient resistor instead of a light bulb? These are used as inrush suppressors in switching power supplies... their initial resistance is high when they're cold, and drops when they warm up. Borrowing the use of a Variac for half an hour is still a better way to do it, I think. -- Dave Platt AE6EO Friends of 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! |
Sending power into rig unused for 30 years : Precautions ?
On Aug 16, 4:03 pm, (Dave Platt) wrote:
Now retired I'm trying to become active again. My TS-520S has not been on for 30 years. I don't have a variactor ( variable transformer ). KISS. Wire a 60w light globe in series, turn it on, let it sit for a few hours. Filaments OFF for this test. Havent used a variac for this for years - reason - its the switch on current surge thats going to kill old electros, and the variac has no current limiting whereas the light bulb does. You will see a brief "Flash" as the caps charge up, then maybe a dull glow, eventually, no light at all. Given that the caps used were / are modern, and of good quality to start with, the KISS method works well. Oh, BTW - when all this is done, apply full mains power, let the tube filaments soak for a few hours lest they have gone gassy. Andrew VK3BFA. |
Sending power into rig unused for 30 years : Precautions ?
I tell you what Dave:
Save the grief and replace the caps. What your'e doing is betting that you can reform the electrolyte that may be left in the capacitors after 30+ years. I hope you win that bet. 73 OM n8zu |
Sending power into rig unused for 30 years : Precautions ?
Andrew VK3BFA wrote:
On Aug 16, 4:03 pm, (Dave Platt) wrote: Now retired I'm trying to become active again. My TS-520S has not been on for 30 years. I don't have a variactor ( variable transformer ). KISS. Wire a 60w light globe in series, turn it on, let it sit for a few hours. Filaments OFF for this test. Havent used a variac for this for years - reason - its the switch on current surge thats going to kill old electros, and the variac has no current limiting whereas the light bulb does. You will see a brief "Flash" as the caps charge up, then maybe a dull glow, eventually, no light at all. ============================================== Don't understand the above. When using a variac starting at zero and gradually increasing the voltage there can't be any appreciable inrush current. I happen to have a 8 Amperes variac and would always use it to 'fire-up' a previously retired oldtimer (boat anchor) I have a rather large junk box with high capacitance value elcos and recently exposed them all to a 'zero to max working voltage' from an adjustable HV PSU. I do that once every 3 years. Frank GM0CSZ / KN6WH |
Sending power into rig unused for 30 years : Precautions ?
On Aug 18, 1:38 am, (Edmund H. Ramm) wrote:
In Andrew VK3BFA writes: Are physics reversed down under? Up here in the old world a light bulb's filament (tungsten) resistance increases with temperature. Er - yes, thats correct.So whats the problem? Andrew VK3BFA. |
Sending power into rig unused for 30 years : Precautions ?
On Aug 17, 11:21 pm, Highland Ham
wrote: ============================================== Don't understand the above. When using a variac starting at zero and gradually increasing the voltage there can't be any appreciable inrush current. I happen to have a 8 Amperes variac and would always use it to 'fire-up' a previously retired oldtimer (boat anchor) I have a rather large junk box with high capacitance value elcos and recently exposed them all to a 'zero to max working voltage' from an adjustable HV PSU. I do that once every 3 years. Frank GM0CSZ / KN6WH Well, mine took out a few SMPS power supplies, and its a pain in the arse to set up, connect meters, gingerly spend time slowly incrementing the voltage - life is too short to stuff around...... Hey, you got time to do Rocket Science, thats fine. Each to his own. Andrew VK3BFA. |
Sending power into rig unused for 30 years : Precautions ?
On Aug 20, 8:27 am, (Edmund H. Ramm) wrote:
In Andrew VK3BFA writes: There will only be negligible inrush current limiting. For that you'll need an NTC resistor like an Epcos NTC22. All you get from a light bulb is a voltage reduction -mains voltage minus the voltage drop across the bulb- but only AFTER the inrush current you intended to prevent has already flown. A light bulb in series with an inrush current limiter might be suitable for smoke testing equipment after prolonged disuse, though. Yes. Whats the DV/DT of the positor versus a light bulb? - I got no idea..... The light bulb method works - its quick and dirty, and so far I have never blown an electrolytic capacitor using this method. Its also VERY useful in firing up SMPS devices - it does current limit quick enough if theres a gross fault to prevent damage. But, each to his own. Of more concern would be corrosion /freezing of pots/switches etc. And a 30 year old mains power cable? - mm - and what about checking the insulation resistance of the power transformer.. But it ain't the Space Shuttle - live dangerously...Just Do It.... Andrew VK3BFA. |
Sending power into rig unused for 30 years : Precautions ?
The light bulb has advantages. It will light up if there is a short. You
can build a rig tester by just putting an outlet in parallel with the light switch, turn it on then plug in and turn on the Rig, then turn off the switch. The light should dim and never get brighter. |
Sending power into rig unused for 30 years : Precautions ?
Edmund H. Ramm wrote:
In Andrew VK3BFA writes: On Aug 18, 1:38 am, (Edmund H. Ramm) wrote: In Andrew VK3BFA writes: Are physics reversed down under? Up here in the old world a light bulb's filament (tungsten) resistance increases with temperature. Er - yes, thats correct.So whats the problem? There will only be negligible inrush current limiting. For that you'll need an NTC resistor like an Epcos NTC22. All you get from a light bulb is a voltage reduction -mains voltage minus the voltage drop across the bulb- but only AFTER the inrush current you intended to prevent has already flown. That lightbulb heats up pretty quickly, especially if there is a short in the radio. Just as a comparison: a 250 watt bulb has a cold resistance of around 3 Ohms. A 60 watt bulb, 18 Ohms A 40 Watt bulb, 25 Ohms I don't have a 25 Watt bulb handy, so I'm not sure of it's cold resistance. But the other bulbs in that neighborhood are at around 14 times the resistance hot vs cold, I'll assume it is around 60 ohms. Sorry for the math here, but R = V squared/P That would equal around 58 Ohms hot resistance for the 250 watt bulb 240 Ohms for the 60 watt bulb 360 Ohms for the 40 watt bulb. 830 Ohms for a 25 watt bulb I usually use a 25 watt bulb, so discounting any inductive effects, I'll be looking at a maximum start current of 240 watts if the radio is a dead short, and that for only a very short period of time. A light bulb in series with an inrush current limiter might be suitable for smoke testing equipment after prolonged disuse, though. There isn't anything wrong with that approach, but it is probably overkill. - 73 de Mike N3LI - |
Sending power into rig unused for 30 years : Precautions ?
On Aug 16, 1:04*am, wrote:
Now retired I'm trying to become active again. My TS-520S has not been on for 30 years. I don't have a variactor ( variable transformer ). At the TARC advice was to put a lightbulb in series to take the surge. * Should I use a high resistance ( low wattage ) bulb or vice versa ? Would this be as good as a simple *L-C network ? Somebody said just plug it in. Are there any other ideas ? Thanks for your kind assistance. Dave WB3DWE *Temple, TX A couple of disclaimers first: a) I know diddly/squat about Ham equipment. I am not a Ham. b) I have been noodling about with vintage equipment, tube & solid- state for now over 30 years, so I am familiar with the species. What I write below is a generic approach to (re)starting vintage equipment after some years at idle. So: As I understand, the Kenwood is a tube-based unit, however it has a solid-state rectifier and is mostly solid-state in general. What this means is that there is some validity to bringing up the voltage slowly using a Variac as the caps will see a gradually increasing voltage - unlike what they would see from a tube rectifier which does not pass current until about 70V or so. That it is from the transistor era, at least in part, suggests that the filter caps may be of sufficiently recent manufacture as to be likely to be good - the operative word here is *LIKELY*, not *certainly*. Kenwood was also not know to use cheap-junk caps in their equipment. HOWEVER: A variac is really no better than a dim-bulb tester unless it is equipped with a current meter (amps or watts) that will read the actual current draw of the unit. I have been known to RANT on this subject at length - but I will spare this group and merely state that UNLESS you have the means to measure actual current drawn by the unit and at a sufficiently fine degree as to give you useful data, don't waste your time with a Variac. It gives you a false sense of security. IF you have the means to measure current - either with your VOM in series or with a poor-man's ammeter (measure voltage drop across a 1- ohm resistor, for example), this technique is very useful. Raise the voltage s-l-o-w-l-y, watching the meter all the time. It will jump up (typically) then slide down as the caps charge. Slowly-slowly-nicely- nicely until you reach operating voltage over 4-5 minutes or so. And KEEP WATCHING! If the caps start to fail at full B+, you will see that meter creep up. If they go anything beyond about 80% (SWAG guess - more below) of the nameplate rating of the unit, you have real problems. Now, here is where I cannot comment beyond the generic - I have no idea what the quiescent vs. active current draw is with the Kenwood. THIS IS IMPORTANT. As you will not be transmitting or whatever, you should be operating at/near the quiescent current. This may be a very small percentage of the full nameplate rating - my guess is that this is so. You will need to know what that is. If you are operating even 5% beyond the "proper" quiescent current, that will be expressed as heat somewhere - and eventually *POOF* at some unobtanium or expensive part. You get the point. The idea is to bring power to the beast slowly so that failed caps or similar may be discovered before any actual damage is done. For this to work you need a means to determine whether the unit is taking excess current - and you need to be able to measure this in fine-enough increments to be worthwhile. Otherwise, you are wasting your time as a small problem or series of small problems will be invisible to crude means. I keep this unit for these sorts of tests: http://www.oaktreeent.com/web_photos...P-5220_web.jpg It is an metered Iso-Variac, overkill for once-in-a-while needs, but I use it constantly. Peter Wieck Melrose Park, PA |
Sending power into rig unused for 30 years : Precautions ?
On Aug 22, 5:06 am, " wrote:
On Aug 16, 1:04 am, wrote: Now retired I'm trying to become active again. My TS-520S has not been on for 30 years. I don't have a variactor ( variable transformer ). At the TARC advice was to put a lightbulb in series to take the surge. Should I use a high resistance ( low wattage ) bulb or vice versa ? Would this be as good as a simple L-C network ? Somebody said just plug it in. Are there any other ideas ? Thanks for your kind assistance. Dave WB3DWE Temple, TX A couple of disclaimers first: a) I know diddly/squat about Ham equipment. I am not a Ham. b) I have been noodling about with vintage equipment, tube & solid- state for now over 30 years, so I am familiar with the species. What I write below is a generic approach to (re)starting vintage equipment after some years at idle. So: As I understand, the Kenwood is a tube-based unit, however it has a solid-state rectifier and is mostly solid-state in general. What this means is that there is some validity to bringing up the voltage slowly using a Variac as the caps will see a gradually increasing voltage - unlike what they would see from a tube rectifier which does not pass current until about 70V or so. That it is from the transistor era, at least in part, suggests that the filter caps may be of sufficiently recent manufacture as to be likely to be good - the operative word here is *LIKELY*, not *certainly*. Kenwood was also not know to use cheap-junk caps in their equipment. HOWEVER: A variac is really no better than a dim-bulb tester unless it is equipped with a current meter (amps or watts) that will read the actual current draw of the unit. I have been known to RANT on this subject at length - but I will spare this group and merely state that UNLESS you have the means to measure actual current drawn by the unit and at a sufficiently fine degree as to give you useful data, don't waste your time with a Variac. It gives you a false sense of security. IF you have the means to measure current - either with your VOM in series or with a poor-man's ammeter (measure voltage drop across a 1- ohm resistor, for example), this technique is very useful. Raise the voltage s-l-o-w-l-y, watching the meter all the time. It will jump up (typically) then slide down as the caps charge. Slowly-slowly-nicely- nicely until you reach operating voltage over 4-5 minutes or so. And KEEP WATCHING! If the caps start to fail at full B+, you will see that meter creep up. If they go anything beyond about 80% (SWAG guess - more below) of the nameplate rating of the unit, you have real problems. Now, here is where I cannot comment beyond the generic - I have no idea what the quiescent vs. active current draw is with the Kenwood. THIS IS IMPORTANT. As you will not be transmitting or whatever, you should be operating at/near the quiescent current. This may be a very small percentage of the full nameplate rating - my guess is that this is so. You will need to know what that is. If you are operating even 5% beyond the "proper" quiescent current, that will be expressed as heat somewhere - and eventually *POOF* at some unobtanium or expensive part. You get the point. The idea is to bring power to the beast slowly so that failed caps or similar may be discovered before any actual damage is done. For this to work you need a means to determine whether the unit is taking excess current - and you need to be able to measure this in fine-enough increments to be worthwhile. Otherwise, you are wasting your time as a small problem or series of small problems will be invisible to crude means. I keep this unit for these sorts of tests: http://www.oaktreeent.com/web_photos...P-5220_web.jpg It is an metered Iso-Variac, overkill for once-in-a-while needs, but I use it constantly. Peter Wieck Melrose Park, PA Peter - lots of good stuff in there, but perhaps overkill..like the ac power supply with its own meters - would be simple to use for the methods you describe. The Kenwood is a "Valve hybrid" - there are 3 tubes in there, a driver and 2 output tubes in //. Filamnets are switchable on/off. Idle current is.....very low, never measured it, had no need to. The light bulb method does work sufficiently well for the purpose intended. Andrew VK3BFA. |
Sending power into rig unused for 30 years : Precautions ?
Andrew VK3BFA wrote:
On Aug 22, 5:06 am, " wrote: Peter - lots of good stuff in there, but perhaps overkill..like the ac power supply with its own meters - would be simple to use for the methods you describe. The Kenwood is a "Valve hybrid" - there are 3 tubes in there, a driver and 2 output tubes in //. Filamnets are switchable on/off. Idle current is.....very low, never measured it, had no need to. The light bulb method does work sufficiently well for the purpose intended. I think I missed just what type of rig it was. If it a Kenwood TS-830, the owner has to immediately ship it to me, as those units had a particular problem that ony I can fix. I tested out one of those, and fell in love with it. Good sound, Hot receiver, good looking rig, The big issue with those was the band changing switch. Not a big deal. Heck, I'll even pay shipping ;^) - 73 de Mike N3LI - |
Sending power into rig unused for 30 years : Precautions ?
Michael Coslo wrote:
I think I missed just what type of rig it was. If it a Kenwood TS-830, the owner has to immediately ship it to me, as those units had a particular problem that ony I can fix. What a dummy I is. That's a TS-530, not 830 - 73 de Mike N3LI - |
Sending power into rig unused for 30 years : Precautions ?
On Aug 17, 6:44*pm, Andrew VK3BFA wrote:
and its a pain in the arse to set up, connect meters, gingerly spend time slowly incrementing the voltage - life is too short to stuff around...... Hey, you got time to do Rocket Science, thats fine. Each to his own. I think that turning it on, blowing up the capacitors that are gonna blow up, and then replacing the ones that actually did blow up is a fine procedure, myself. There is a certain pussyfoot attitude about either cranking up the variac gingerly, or simply recapping the whole radio, that is not really appropriate to somebody (me!) who really wants to see smoke coming out at least once in a while. Only gotcha, if the bad capacitor takes out a transformer, that's a PITA. Not that I've never rewound bad transformers or rewound them for a project, but having to rewind a transformer just because I was impatient is a little embarassing. Tim. |
Sending power into rig unused for 30 years : Precautions ?
On Aug 22, 2:52 pm, Tim Shoppa wrote:
I think that turning it on, blowing up the capacitors that are gonna blow up, who really wants to see smoke coming out at least once in a while. You been watching to much myth busters? Only gotcha, if the bad capacitor takes out a transformer, that's a PITA. Not that I've never rewound bad transformers or rewound them for a project, but having to rewind a transformer just because I was impatient is a little embarassing. I think you going to has to jump the fuse to get away with that? Nothing I hate more than shorted parts especially a shorted fuse. 73 OM n8zu |
Sending power into rig unused for 30 years : Precautions ?
In article
s.com, writes A couple of disclaimers first: a) I know diddly/squat about Ham equipment. I am not a Ham. b) I have been noodling about with vintage equipment, tube & solid- state for now over 30 years, so I am familiar with the species. What I write below is a generic approach to (re)starting vintage equipment after some years at idle. ....snip... sounds good Just to add. In the days when boat anchor stuff was the normal gear, when items had been on the shelf in storage for long periods, the electrolytics were not so good then as now :) Switch on procedure from storage was: 1. Expect the odd "phut and horrible smell." It *will* happen at some time. 2. Switch on for a few seconds and then off - allows the electrolytic barrier in the capacitor to start to re-form - the number of seconds for certain equipment was specified - otherwise about 5 seconds for the first time. 3. Switch off for about 60 minutes. 4. Switch on for 10 secs and then off for 30 mins. 5 Switch on for 30 secs and then off for 30 mins. 6. On for 30 sec off for 10 mins. 7. On for 60 sec off for 5 mins. 8. And so on.... These were valuable equipments and the manufacturer normally laid down a procedure. The whole idea being to re-form the electrolytic capacitors and to give other problems time to cool down for inspection and detection/rectification. The alternative was just to switch on and then stand back from the bench with your fingers in your ears and a handkerchief over your nose :D John -- JC Morrice |
Sending power into rig unused for 30 years : Precautions ?
On Aug 23, 7:35 pm, JC Morrice wrote:
In article And so, like all good "tinny and bull****" sessions, we come back to the original question - if Dave hasn't wandered off, in boredom or disgust. And like all good amateur arguments, we have suggestions ranging from ludicrous to....ludicrous. We have had - an engineered, high tech solution A stuff it, just power it up solution The KISS solution - use a light bulb in series The do it slowly and painstakingly with a metered variac solution Some reminiscences about the "old days" Someone else offered to buy the radio, but got their models mixed up. Answers from people who, well, really....dunno why.... And all valid, all correct - so, Dave - take your pick which one YOU use.......alternatively, there is a TS520/530/820/830 group on Yahoo. You could post your question there - they have heaps of people who lovingly use, restore these old radios - mind you, the answers will be as broad spectrum as here, and LOTS more off em hi hi. Andrew VK3BFA. |
Sending power into rig unused for 30 years : Precautions ?
On Aug 23, 5:23*am, raypsi wrote:
On Aug 22, 2:52 pm, Tim Shoppa wrote: I think that turning it on, blowing up the capacitors that are gonna blow up, who really wants to see smoke coming out at least once in a while. You been watching to much myth busters? Not really, but a former schoolmate has worked at a place titled "Center for Non-Destructive Testing" and my first comment to him (like 15 years ago) was "Where's the fun in that?" Only gotcha, if the bad capacitor takes out a transformer, that's a PITA. Not that I've never rewound bad transformers or rewound them for a project, but having to rewind a transformer just because I was impatient is a little embarassing. *I think you going to has to jump the fuse to get away with that? Nothing I hate more than shorted parts especially a shorted fuse. The fuse is there to help (not guarantee) stop things from catching on fire and burning down your house. It's not there to save components. It is sized based on primary current, not the current capacity of any individual secondary or the components hooked to any individual secondary. Tim N3QE |
Sending power into rig unused for 30 years : Precautions ?
Andrew VK3BFA wrote:
On Aug 16, 4:03 pm, (Dave Platt) wrote: Now retired I'm trying to become active again. My TS-520S has not been on for 30 years. I don't have a variactor ( variable transformer ). KISS. Wire a 60w light globe in series, turn it on, let it sit for a few hours. Filaments OFF for this test. Havent used a variac for this for years - reason - its the switch on current surge thats going to kill old electros, and the variac has no current limiting whereas the light bulb does. You will see a brief "Flash" as the caps charge up, then maybe a dull glow, eventually, no light at all. Given that the caps used were / are modern, and of good quality to start with, the KISS method works well. Oh, BTW - when all this is done, apply full mains power, let the tube filaments soak for a few hours lest they have gone gassy. Andrew VK3BFA. Well I still use a kenwood 820s and it goes fine. In fact I'm just putting the WARC bands into it. The only parts I would be really concerned about are the 450 vot electros in series acroos the 800 volt final ht supply. If you were very careful a good look at the caps smoothing the 300 volt screen and driver plate supply might also be a good idea. If you do a search on google you will find all the tech data you might need including circuits and manuals. It's a pretty good rig except for some poor final tank design on some bands. a rewind of the Pi network inductor can help a lot and the use of the proper values for a working Q of 12. This can give you up to 25 or 30 watts more output on some bands with no more DC input. It also saves you finals a lot of potential grief. See the QST 1983 upgrade article for a few ideas. Cliff Wright ZL1BDA ex G3NIA |
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