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MFJ-269 repair (I win)
I just repaired an old MFJ-269 antenna analyzer. This time, the 4
diodes around the RF connector were NOT blown. Instead, it was crappy SMT soldering for the components surrounding the diodes. The solder joints looked ok before I resoldered them, but were obviously a bad connection because several resistors just fell off the board when I touched one end with the soldering iron, indicating the other end was not properly soldered. With the resistor removed, the PCB pad looked like it had never been soldered. If you don't have good soldering tools, a steady hand, and a good microscope, DON'T try this as you'll probably make a mess, as I did before I realized what was happening. Because the various parts on the RF board were not originally making good contact to the PCB pads, the calibration is off. The display reads about 12% too high for impedance and dead on for reactance. I'm debating if it's worth calibrating. http://www.w8ji.com/mfj-259b_calibration.htm Now working on an MFJ-259A, which looks like the usual blown diode problem: http://802.11junk.com/jeffl/MFJ-269-repair/ -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
MFJ-269 repair (I win)
On 11/7/2015 8:25 PM, Jeff Liebermann wrote:
I just repaired an old MFJ-269 antenna analyzer. This time, the 4 diodes around the RF connector were NOT blown. Instead, it was crappy SMT soldering for the components surrounding the diodes. The solder joints looked ok before I resoldered them, but were obviously a bad connection because several resistors just fell off the board when I touched one end with the soldering iron, indicating the other end was not properly soldered. With the resistor removed, the PCB pad looked like it had never been soldered. If you don't have good soldering tools, a steady hand, and a good microscope, DON'T try this as you'll probably make a mess, as I did before I realized what was happening. Because the various parts on the RF board were not originally making good contact to the PCB pads, the calibration is off. The display reads about 12% too high for impedance and dead on for reactance. I'm debating if it's worth calibrating. http://www.w8ji.com/mfj-259b_calibration.htm Now working on an MFJ-259A, which looks like the usual blown diode problem: http://802.11junk.com/jeffl/MFJ-269-repair/ That's how I got my MFJ-259B, about 15 years ago, Someone at the local ham club had a defective one, gave it to a fellow ham to fix, he returned it saying that he couldn't fix it. I told the owner, let me have a shot at it, if I can fix it I'll buy it from you. It was "the usual blown diode problem:" I shocked the owner when I gave him $60.00 for the repaired unit. I don't think he expected me to contact him again. Mikek |
MFJ-269 repair (I win)
On 11/9/2015 11:18 AM, amdx wrote:
On 11/7/2015 8:25 PM, Jeff Liebermann wrote: I just repaired an old MFJ-269 antenna analyzer. This time, the 4 diodes around the RF connector were NOT blown. Instead, it was crappy SMT soldering for the components surrounding the diodes. The solder joints looked ok before I resoldered them, but were obviously a bad connection because several resistors just fell off the board when I touched one end with the soldering iron, indicating the other end was not properly soldered. With the resistor removed, the PCB pad looked like it had never been soldered. If you don't have good soldering tools, a steady hand, and a good microscope, DON'T try this as you'll probably make a mess, as I did before I realized what was happening. Because the various parts on the RF board were not originally making good contact to the PCB pads, the calibration is off. The display reads about 12% too high for impedance and dead on for reactance. I'm debating if it's worth calibrating. http://www.w8ji.com/mfj-259b_calibration.htm Now working on an MFJ-259A, which looks like the usual blown diode problem: http://802.11junk.com/jeffl/MFJ-269-repair/ That's how I got my MFJ-259B, about 15 years ago, Someone at the local ham club had a defective one, gave it to a fellow ham to fix, he returned it saying that he couldn't fix it. I told the owner, let me have a shot at it, if I can fix it I'll buy it from you. It was "the usual blown diode problem:" I shocked the owner when I gave him $60.00 for the repaired unit. I don't think he expected me to contact him again. Mikek Good for you Mike, I once came across an Ameritron ALS-600 with analogue power supply and a couple of vhf-uhf transceivers in a junk box at a garage sale. I asked how much for the whole box. I was told 60 bucks. I assumed the stuff was probably defective. However, the person selling it was a woman who had lost her ham husband. I wrote her a check for $500. That is what I figured a defective ALS-600 might be worth. She was shocked. I did not do this to be generous. I did it because I knew that if I really screwed her on that deal, I would feel guilty every time I used that amplifier. It turned out that the amplifier actually worked but introduced a bit of distortion. I sent it to MFJ and they rebalanced the output transistors. It has very good fidelity now. The trip to MFJ cost about 200 dollars. I had to buy one of their shipping boxes. Those are not cheap. Still, 700 dollars for an ALS-600 is a bargain. I liked that design so well that I bought an ALS-1300 which is just two ALS-600s in a box. So, I have the 600 as a backup amp. That 1300 has been such a good work horse. Tom at MFJ and others who worked on that amp design did a fine job. Originally there was a defect in the switching supply that they bought for it. Mine has been updated to protect the 12 volt supply. |
MFJ-269 repair (I win)
In article ,
Jeff Liebermann wrote: Now working on an MFJ-259A, which looks like the usual blown diode problem: http://802.11junk.com/jeffl/MFJ-269-repair/ "Of course, when I got it back together (for the 2nd time), I found the reading to be erratic and intermittent. It took a while to discover that the owner had somehow spread the gold center contact leafs in the type-N connector and my adapter wasn't making contact." My repeater cohort and I have seen quite a few N connectors which were damaged in precisely this fashion. One cause: some N-connector adapters floating around out there have center pins which are either too large in diameter, improperly tapered, or which protrude too far "forwards". I suspect that male N connectors, if improperly installed, can have the same problem (the pin is pushed too far into the connector). In either case, (over)tightening such an N-male connector onto an N-female will cause it to make excellent contact... once... as the pin splays the female connector's contacts outwards. Subsequent connection attempts with a properly-configured N male won't make good contact. In a pinch, you can try pinching the contact fingers back in, but it's nigh-on impossible to restore them properly. Better to remove the damaged female connector and replace it. Then, check all of your male N connectors to make sure the center pin has the proper taper and is in the proper position. A center pin with a rounded blunt end (rather than a properly-tapered point) is Trouble. This turned out to be all that was wrong with a defective TK-981 I picked up at the De Anza ham flea market last year. Cut off the N connector, solder-and-crimp a new one onto the pigtail, and it checks out fine. |
MFJ-269 repair (I win)
Dave Platt wrote:
One cause: some N-connector adapters floating around out there have center pins which are either too large in diameter, improperly tapered, or which protrude too far "forwards". I suspect that male N connectors, if improperly installed, can have the same problem (the pin is pushed too far into the connector). With some types of cable, there is a tendency for the inner conductor to "lengthen" relative to the outer shield when the cable is repeatedly wound and unwound in a small radius. This can sometimes push out the connector pin a little. |
MFJ-269 repair (I win)
On Mon, 9 Nov 2015 11:18:20 -0600, amdx wrote:
That's how I got my MFJ-259B, about 15 years ago, Someone at the local ham club had a defective one, gave it to a fellow ham to fix, he returned it saying that he couldn't fix it. I told the owner, let me have a shot at it, if I can fix it I'll buy it from you. It was "the usual blown diode problem:" I shocked the owner when I gave him $60.00 for the repaired unit. I don't think he expected me to contact him again. Mikek Yep. I'm working on an MFJ-259B which might have blown diodes. It's very easy to do. I'm considering adding a 1M resistor from the center pin to ground to bleed off any static buildup. Beware of ungrounded antennas. BTW, I paid $100 for mine. Grumble... I'm also working with another ham that has an old MFJ-269 with some very strange problems. I can't conjur a theory except that his has the same problem as mine with the crappy soldering on the RF PCB. I've recommended reflowing all the SMT parts around the coax connector. That should either fix it, or destroy it. Drivel: I'm trying to find a replacement LCD 1602 display with backlighting. Plenty on eBay, but all the wrong size. Argh. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
MFJ-269 repair (I win)
"Dave Platt" wrote in message
... In article , Jeff Liebermann wrote: Now working on an MFJ-259A, which looks like the usual blown diode problem: http://802.11junk.com/jeffl/MFJ-269-repair/ "Of course, when I got it back together (for the 2nd time), I found the reading to be erratic and intermittent. It took a while to discover that the owner had somehow spread the gold center contact leafs in the type-N connector and my adapter wasn't making contact." My repeater cohort and I have seen quite a few N connectors which were damaged in precisely this fashion. The N connector is so-called because there are N different ways to assemble it, and all of them wrong :-) |
MFJ-269 repair (I win)
On 11/7/2015 8:25 PM, Jeff Liebermann wrote:
I just repaired an old MFJ-269 antenna analyzer. This time, the 4 diodes around the RF connector were NOT blown. Instead, it was crappy SMT soldering for the components surrounding the diodes. The solder joints looked ok before I resoldered them, but were obviously a bad connection because several resistors just fell off the board when I touched one end with the soldering iron, indicating the other end was not properly soldered. With the resistor removed, the PCB pad looked like it had never been soldered. If you don't have good soldering tools, a steady hand, and a good microscope, DON'T try this as you'll probably make a mess, as I did before I realized what was happening. Because the various parts on the RF board were not originally making good contact to the PCB pads, the calibration is off. The display reads about 12% too high for impedance and dead on for reactance. I'm debating if it's worth calibrating. http://www.w8ji.com/mfj-259b_calibration.htm Now working on an MFJ-259A, which looks like the usual blown diode problem: http://802.11junk.com/jeffl/MFJ-269-repair/ I've generally found MFJ stuff has decent design and rather good components, but terrible wave soldering on the PC boards (and sometimes hand soldering on components off the board like chassis mounted connectors). On my 259B, it worked well for almost a year, and then became erratic. When I saw how many soldered joints weren't, I decided not to try to figure out which ones were bad: I just went around and resoldered everything on the board. Since then it has worked perfectly. Wave soldering is a marginal thing, I think it is amazing how many times it does work. Think about how it goes: Basically the PC board is suspended just above a vat of molten solder, and a wave is caused to run across the vat. The wave, we hope, just reaches up to the connections on the board and solders them. Too high and it makes solder bridges. Too low and it either misses connections or at least does not stay on them long enough. And it is not long on a connection at best, so does it get it hot enough? It is not just fairly inexpensive things like my MFJ analyzer that have had problems. I did the "resolder the whole board" thing on my Phase Linear preamp many years ago also, and that was by no means low end! Bob Wilson |
MFJ-269 repair (I win)
I have a number of MFJ items that I picked up in non-working
conditions and fixed up. They include MFJ-259B, MFJ-931, MFJ-949E and others. Other than the 259B which involved cleaning leaky battery residue and replacing the input diodes. most of the work involved resoldering and/or replacing blown meters, and in once case a bandswitch. Once repaired, everything has remained totally reliable and functional. I've never had problems ordering parts from them to fix the stuff. The 'Mighty Fine Junk' reputation is deserved only because of the poor soldering, but once repaired it serves one well -- at least in my books! Irv VE6BP |
MFJ-269 repair (I win)
On Thu, 12 Nov 2015 12:20:53 -0600, "Robert L Wilson Jr."
wrote: I was afraid that my rant was going to turn into a discussion on MFJ quality or lack thereof. I was more interested in giving owners of the various MFJ antenna analyzers a clue as to what might be wrong with theirs, than attempting to fix the problem at the source. I'm sure MFJ knows that they have a problem by now. Wave soldering is a marginal thing, I think it is amazing how many times it does work. Think about how it goes: Basically the PC board is suspended just above a vat of molten solder, and a wave is caused to run across the vat. The wave, we hope, just reaches up to the connections on the board and solders them. Nope. PCB's with surface mount devices are not wave soldered. I worked for several companies that had wave solder machinery during the 1970's, before SMT parts were common. Keeping the production line machinery going was one my side projects. These daze, components are attached with solder paste and soldered using infrared or vapor phase reflow ovens. Please note that the MFJ-269 PCB's have all the components on the component side and have no leaded components on the board (except for some flex wires to the meter and battery and several ribbon cables). Too high and it makes solder bridges. Nope. Too low a temperature and you get bridging. The wave has to touch the pads on the bottom of the PCB or the pads don't get soldered. Too low a wave is a bigger problem, where the pads don't get any solder. Too low and it either misses connections or at least does not stay on them long enough. Soldering time is controlled by the speed of the chain drive moving the PAB across the wave, not by the height of the wave. There might be a tiny variation in timing with height, but with the nearly vertical sides of the wave caused by the weight of the solder, the soldering time is about the same for all wave heights. And it is not long on a connection at best, so does it get it hot enough? We had thermocouples stuck into the wave to control the temperature. At worst, were off a few degrees one way or the other. It is not just fairly inexpensive things like my MFJ analyzer that have had problems. I did the "resolder the whole board" thing on my Phase Linear preamp many years ago also, and that was by no means low end! Bob Wilson I'm still slightly mystified how the components looked like they were properly soldered, while the solder didn't stick to the PCB pad. The best I can offer is some grease on the pads. Also, it was only in one part of the PCB (around the RF connector). The other half of the RF board was just fine. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
MFJ-269 repair (I win)
On 12/11/15 18:20, Robert L Wilson Jr. wrote:
On 11/7/2015 8:25 PM, Jeff Liebermann wrote: I just repaired an old MFJ-269 antenna analyzer. This time, the 4 diodes around the RF connector were NOT blown. Instead, it was crappy SMT soldering for the components surrounding the diodes. The solder joints looked ok before I resoldered them, but were obviously a bad connection because several resistors just fell off the board when I touched one end with the soldering iron, indicating the other end was not properly soldered. With the resistor removed, the PCB pad looked like it had never been soldered. If you don't have good soldering tools, a steady hand, and a good microscope, DON'T try this as you'll probably make a mess, as I did before I realized what was happening. Because the various parts on the RF board were not originally making good contact to the PCB pads, the calibration is off. The display reads about 12% too high for impedance and dead on for reactance. I'm debating if it's worth calibrating. http://www.w8ji.com/mfj-259b_calibration.htm Now working on an MFJ-259A, which looks like the usual blown diode problem: http://802.11junk.com/jeffl/MFJ-269-repair/ I've generally found MFJ stuff has decent design and rather good components, but terrible wave soldering on the PC boards (and sometimes hand soldering on components off the board like chassis mounted connectors). On my 259B, it worked well for almost a year, and then became erratic. When I saw how many soldered joints weren't, I decided not to try to figure out which ones were bad: I just went around and resoldered everything on the board. Since then it has worked perfectly. Wave soldering is a marginal thing, I think it is amazing how many times it does work. Think about how it goes: Basically the PC board is suspended just above a vat of molten solder, and a wave is caused to run across the vat. The wave, we hope, just reaches up to the connections on the board and solders them. Too high and it makes solder bridges. Too low and it either misses connections or at least does not stay on them long enough. And it is not long on a connection at best, so does it get it hot enough? It is not just fairly inexpensive things like my MFJ analyzer that have had problems. I did the "resolder the whole board" thing on my Phase Linear preamp many years ago also, and that was by no means low end! Bob Wilson ======= What strikes me in this newsgroup thread , time and again, is that MFJ´s quality control people (if they exist) pass badly soldered PCBs and other imperfections which affect their products´ reliability . But for some reason they get away with it. To me this seems to be an attitude brought about by management.........Martin F. Jue ? Frank , GM0CSZ / KN6WH |
MFJ-269 repair (I win)
On 11/14/2015 2:11 PM, highlandham wrote:
On 12/11/15 18:20, Robert L Wilson Jr. wrote: On 11/7/2015 8:25 PM, Jeff Liebermann wrote: I just repaired an old MFJ-269 antenna analyzer. This time, the 4 diodes around the RF connector were NOT blown. Instead, it was crappy SMT soldering for the components surrounding the diodes. The solder joints looked ok before I resoldered them, but were obviously a bad connection because several resistors just fell off the board when I touched one end with the soldering iron, indicating the other end was not properly soldered. With the resistor removed, the PCB pad looked like it had never been soldered. If you don't have good soldering tools, a steady hand, and a good microscope, DON'T try this as you'll probably make a mess, as I did before I realized what was happening. Because the various parts on the RF board were not originally making good contact to the PCB pads, the calibration is off. The display reads about 12% too high for impedance and dead on for reactance. I'm debating if it's worth calibrating. http://www.w8ji.com/mfj-259b_calibration.htm Now working on an MFJ-259A, which looks like the usual blown diode problem: http://802.11junk.com/jeffl/MFJ-269-repair/ I've generally found MFJ stuff has decent design and rather good components, but terrible wave soldering on the PC boards (and sometimes hand soldering on components off the board like chassis mounted connectors). On my 259B, it worked well for almost a year, and then became erratic. When I saw how many soldered joints weren't, I decided not to try to figure out which ones were bad: I just went around and resoldered everything on the board. Since then it has worked perfectly. Wave soldering is a marginal thing, I think it is amazing how many times it does work. Think about how it goes: Basically the PC board is suspended just above a vat of molten solder, and a wave is caused to run across the vat. The wave, we hope, just reaches up to the connections on the board and solders them. Too high and it makes solder bridges. Too low and it either misses connections or at least does not stay on them long enough. And it is not long on a connection at best, so does it get it hot enough? It is not just fairly inexpensive things like my MFJ analyzer that have had problems. I did the "resolder the whole board" thing on my Phase Linear preamp many years ago also, and that was by no means low end! Bob Wilson ======= What strikes me in this newsgroup thread , time and again, is that MFJ´s quality control people (if they exist) pass badly soldered PCBs and other imperfections which affect their products´ reliability . But for some reason they get away with it. To me this seems to be an attitude brought about by management.........Martin F. Jue ? Frank , GM0CSZ / KN6WH It is too often that some of these things get past QC. The good news is that some of their products, like their linear amplifiers have allowed the ordinary ham to run power. Other amplifiers always cost more and seem to be no more reliable than an Ameritron model. I have two, the ALS-600 and the 1300. Both have been excellent products for me. I did have an AL-80B, but sold it. Most of us hams do not have the money to go out and buy an Alpha amp. From my own experience, I can tell not difference in the signal from an Alpha or Tokyo from an Ameritron. I am guessing that Martin is pushing those products through QC very quickly to keep margins up. It is a balance between QC and profit margin that is probably hard to find. My own guess is that if he put more emphasis on QC and charged a bit more for each product, that his business would do better just from the reputation he would gain. |
MFJ-269 repair (I win)
"Tom" wrote in message ... Most of us hams do not have the money to go out and buy an Alpha amp. From my own experience, I can tell not difference in the signal from an Alpha or Tokyo from an Ameritron. I am guessing that Martin is pushing those products through QC very quickly to keep margins up. It is a balance between QC and profit margin that is probably hard to find. My own guess is that if he put more emphasis on QC and charged a bit more for each product, that his business would do better just from the reputation he would gain. I think Ameritron was bought by MFJ as they have bought a few other companies. I have only bought 2 items made by MFJ. One was a packet tnc years ago. It was defective and I sent it back. They sent me a new one and I had it in about 3 days. No problem on that as I know it is easy for a new item to be defective out of the box and they did ship a new one just as fast as possiable. About 5 years later I bought a new antenna tuner from a dealer at a hamfest. It had loose screws and after I tightened them and recalibrated the wattmeter that was way off with a Bird meter, it seemed to work fine. The schematic in the manual did not match the tuner either. I try not to even look at the MFJ items due to the poor reputation of the quality control. From what I am hearing, when MFJ buys a company, the quality goes down hill. |
MFJ-269 repair (I win)
"Tom" wrote in message ... On 11/14/2015 2:11 PM, highlandham wrote: On 12/11/15 18:20, Robert L Wilson Jr. wrote: On 11/7/2015 8:25 PM, Jeff Liebermann wrote: I just repaired an old MFJ-269 antenna analyzer. This time, the 4 diodes around the RF connector were NOT blown. Instead, it was crappy SMT soldering for the components surrounding the diodes. The solder joints looked ok before I resoldered them, but were obviously a bad connection because several resistors just fell off the board when I touched one end with the soldering iron, indicating the other end was not properly soldered. With the resistor removed, the PCB pad looked like it had never been soldered. If you don't have good soldering tools, a steady hand, and a good microscope, DON'T try this as you'll probably make a mess, as I did before I realized what was happening. Because the various parts on the RF board were not originally making good contact to the PCB pads, the calibration is off. The display reads about 12% too high for impedance and dead on for reactance. I'm debating if it's worth calibrating. http://www.w8ji.com/mfj-259b_calibration.htm Now working on an MFJ-259A, which looks like the usual blown diode problem: http://802.11junk.com/jeffl/MFJ-269-repair/ I've generally found MFJ stuff has decent design and rather good components, but terrible wave soldering on the PC boards (and sometimes hand soldering on components off the board like chassis mounted connectors). On my 259B, it worked well for almost a year, and then became erratic. When I saw how many soldered joints weren't, I decided not to try to figure out which ones were bad: I just went around and resoldered everything on the board. Since then it has worked perfectly. Wave soldering is a marginal thing, I think it is amazing how many times it does work. Think about how it goes: Basically the PC board is suspended just above a vat of molten solder, and a wave is caused to run across the vat. The wave, we hope, just reaches up to the connections on the board and solders them. Too high and it makes solder bridges. Too low and it either misses connections or at least does not stay on them long enough. And it is not long on a connection at best, so does it get it hot enough? It is not just fairly inexpensive things like my MFJ analyzer that have had problems. I did the "resolder the whole board" thing on my Phase Linear preamp many years ago also, and that was by no means low end! Bob Wilson ======= What strikes me in this newsgroup thread , time and again, is that MFJ´s quality control people (if they exist) pass badly soldered PCBs and other imperfections which affect their products´ reliability . But for some reason they get away with it. To me this seems to be an attitude brought about by management.........Martin F. Jue ? Frank , GM0CSZ / KN6WH # It is too often that some of these things get past QC. The good news is # that some of their products, like their linear amplifiers have allowed # the ordinary ham to run power. . MFJ seems to have gotten a bit better as the years go by. Once I bought something (a cw filter perhaps) that had the PC board mounted by wedging it at an angle and using a bead of epoxy to hold it in place. I haven't seen that kind of sloppy work from them in a while. |
MFJ-269 repair (I win)
"Robert L Wilson Jr." wrote in message ... snip It is not just fairly inexpensive things like my MFJ analyzer that have had problems. I did the "resolder the whole board" thing on my Phase Linear preamp many years ago also, and that was by no means low end! Bob Wilson ++++++++++++++++++++++++++++++++++++++++++++++++++ +++++++++++++++ In 1970, I bought a new Chevy Impala, drove it for a couple of years, including cross-country. One day the radio quit. One dashboard-thump later, the radio was back. After another YEAR, the radio quit again and no amount of thumping had any effect. On the weekend, I pulled it and opened it. Inside, a single wire ran from the DC plug on the back to the ON/OFF switch. The front end of that wire was looped through a lug on the switch but it had never been soldered. Not a trace of solder on the lug or the wire. After a minute's work and a centimeter of solder, I had my radio back. No more problems. How/why did it work all those years ... then abruptly quit, work again, then quit again? Unexplained. |
MFJ-269 repair (I win)
"Jeff Liebermann" wrote in message ... I'm still slightly mystified how the components looked like they were properly soldered, while the solder didn't stick to the PCB pad. The best I can offer is some grease on the pads. Also, it was only in one part of the PCB (around the RF connector). The other half of the RF board was just fine. ================================================== ========= Showing my age, I worked on a tube TV which had a red hum bar floating up through an essentially normal color picture. The ground on the R-Y amp tube heater needed to be resoldered. It was a quick fix after hours of fruitless troubleshooting. (A high resistance joint caused the 60 Hz A/C voltage to be coupled onto the cathode, modulating the R-Y signal. Oddly, the tube was lit, keeping us from looking where the trouble lay.) |
MFJ-269 repair (I win)
"highlandham" wrote in message ... snip What strikes me in this newsgroup thread , time and again, is that MFJ´s quality control people (if they exist) pass badly soldered PCBs and other imperfections which affect their products´ reliability . But for some reason they get away with it. To me this seems to be an attitude brought about by management.........Martin F. Jue ? Frank , GM0CSZ / KN6WH ================================================== ======= I picked up an MFJ "Deluxe Versatuner" at a ham swap meet. I opened it at home to give it some poking and prodding. I quickly discovered that most of the hardware need to be tightened or retightened -- if it was ever tight. This reminds me to open it again. It's been a few years. :-) "Sal" (really KD6VKW) |
MFJ-269 repair (I win)
On 1/21/2016 10:32 PM, Sal M. O'Nella wrote:
"highlandham" wrote in message ... snip What strikes me in this newsgroup thread , time and again, is that MFJ´s quality control people (if they exist) pass badly soldered PCBs and other imperfections which affect their products´ reliability . But for some reason they get away with it. To me this seems to be an attitude brought about by management.........Martin F. Jue ? Frank , GM0CSZ / KN6WH ================================================== ======= I picked up an MFJ "Deluxe Versatuner" at a ham swap meet. I opened it at home to give it some poking and prodding. I quickly discovered that most of the hardware need to be tightened or retightened -- if it was ever tight. This reminds me to open it again. It's been a few years. :-) "Sal" (really KD6VKW) It's not just what we first think of as electronics: I have a Chevrolet pickup truck, and the windshield wipers quit working. (Of course it happened during an intense storm while I was far from home.) Online I found that (a) it was a common problem among many models from General Motors (not just Chevy) for quite a few years, and (b) if you went to the dealer they would install a new wiper motor for about $200. I took the motor out and disassembled it. There was a surprisingly complicated PC board governing the several different speeds of operation. And, of course, at least half the soldered connections needed to be redone. It has now worked fine for another decade, but I feel badly about the (hundreds of?) thousands of people who wasted all that money, and all the wasted (probably trashed rather than recycled) motors and gear trains and electronics, etc. Maybe I should be amazed at how well so much of our electronics does work, if it is this hard (read expensive to the manufacturer, not really difficult!) to do mass production PC board soldering right! Bob Wilson |
MFJ-269 repair (I win)
On Saturday, November 7, 2015 at 8:25:39 PM UTC-6, Jeff Liebermann wrote:
I just repaired an old MFJ-269 antenna analyzer. This time, the 4 diodes around the RF connector were NOT blown. Instead, it was crappy SMT soldering for the components surrounding the diodes. The solder joints looked ok before I resoldered them, but were obviously a bad connection because several resistors just fell off the board when I touched one end with the soldering iron, indicating the other end was not properly soldered. With the resistor removed, the PCB pad looked like it had never been soldered. If you don't have good soldering tools, a steady hand, and a good microscope, DON'T try this as you'll probably make a mess, as I did before I realized what was happening. Because the various parts on the RF board were not originally making good contact to the PCB pads, the calibration is off. The display reads about 12% too high for impedance and dead on for reactance. I'm debating if it's worth calibrating. http://www.w8ji.com/mfj-259b_calibration.htm Now working on an MFJ-259A, which looks like the usual blown diode problem: http://802.11junk.com/jeffl/MFJ-269-repair/ -- snip.. Hi Jeff & the list, I found your post while looking for potential solutions to the problem I'm having with my MFJ-269. It seems to work fine below UHF. Activating the UHF portion, I see "Increase Frequency" in the display, which is usually followed by "Voltage Low .2Volts". I wonder if you've seen this problem before and if you might share any insight as to the usual cause of it. Thank you, Robin K4IDC |
MFJ-269 repair (I win)
I need my mfj analyser 259 repaired
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MFJ-269 repair (I win)
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