Resurrected a Customized WOPL 400
- Thread starter scottonnob
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First thing I'd do is disassemble the whole thing and start over with the soldering of the PEM's. They don't look like they are even down all the way on the board.
Did you follow Joes directions as far as wire length pertaining to the wires from the back planes to the control board? Also the wires from the back plane to the control board for the bias wires? Those are critical for wire length (5.5" max). Take them all out and solder them to the other side of the control board so we can follow wire colors. I'd also double check the back side of the back planes for protruding tails. It's strange that you blew one channel, fixed it, then the other channel blew. Your fuses on the back planes, if they are blown, would possibly indicate a tail too long. The solder points look bad but that could be my shitty laptop but I see too much solder which is worse than not enough since the BP clearance is limited. You should have bought the phoenix connectors for the control board. They make the job so much easier.
Did you follow Joes directions as far as wire length pertaining to the wires from the back planes to the control board? Also the wires from the back plane to the control board for the bias wires? Those are critical for wire length (5.5" max). Take them all out and solder them to the other side of the control board so we can follow wire colors. I'd also double check the back side of the back planes for protruding tails. It's strange that you blew one channel, fixed it, then the other channel blew. Your fuses on the back planes, if they are blown, would possibly indicate a tail too long. The solder points look bad but that could be my shitty laptop but I see too much solder which is worse than not enough since the BP clearance is limited. You should have bought the phoenix connectors for the control board. They make the job so much easier.
Those PEM's, if not flat on the board, will cause the output leads to not go through the solder cups (which have WAY TOO MUCH SOLDER) and they cause the back plane boards to stick up and when you tighten the outputs will cause the boards to flex and cause unrepairable cracking of the back planes. Send it to me and I'll rework it and have it back to you in a few weeks. Just pay shipping. I hate to see a build last 6 years, it's painful.
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Okay, the first issue is that those are old photographs. The bias transistors have been replaced and the holders aligned properly. I did a reflow on all the wires from the backplanes to control board. They are solid and I've checked them with a magnifying glass and DMM. I followed Joe's directions to the letter, you know, as far as the lengths are concerned. The backplanes were both entirely reworked and triple checked. The channel isn't blown, it's just dead at the bias. It passed some very quiet, very distorted sound when I brought it up, but something was clearly not working correctly. Additionally, there isn't any voltage at the bias check point. That's when I shut it down and started looking for problems. There are no blown fused, pico or otherwise and no blown resistors. If I can't figure this out, I will definitely just send it to you. I'm frustrated and tired of working on it. I rebuilt my 3300 and it's sounding so sweet I can't wait to get it hooked up to the 400. Right now, it's running through a Rotel amp that's pretty old and stock. Also, the DBT/Variac bring up went off without a hitch. No problems or indications of problems. I can plug it in straight to power now and there isn't a problem, but the dead channel remains. I understand that my soldering may not look professional, but I check everything and always make certain that the joints are solid and discrete. Putting new photos in post.
SO I ask one last time, did it come up on the DBT WITH BIAS the first time or was bias dead on the one channel?????? Did you ever get music from both channels at the same time?
It makes a difference of where and what to look at. If it NEVER worked correctly, and blew a channel (a dead channel is considered BLOWN), immediately, you fixed the blown channel and then the other channel blew, I'd be tearing out the back planes and start over.
It makes a difference of where and what to look at. If it NEVER worked correctly, and blew a channel (a dead channel is considered BLOWN), immediately, you fixed the blown channel and then the other channel blew, I'd be tearing out the back planes and start over.
The right channel black wire for the bias transistor has a bald spot on it about 2" off the back of the control board which may have taken out your right bias transistor because it is a short waiting to happen.
If the back of the back planes look like the back of the control board, it needs to come apart. It (the amp), won't survive even if you can get it running.
If the back of the back planes look like the back of the control board, it needs to come apart. It (the amp), won't survive even if you can get it running.
Scott, that control board needs total rework. Looking at the photo of it, especially the solder side, shows all the cold solder/overheated solder/uncleaned flux/solder blobs and I would not plan on that board keeping the amp working for any length of time. Those joints are NOT solid nor discrete. Still waiting for the reply on the top right channel PEM right at the edge of the DCP. It looks pulled and missing.
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"I ask one last time, did it come up on the DBT WITH BIAS the first time or was bias dead on the one channel (one channel was dead)?????? Did you ever get music from both channels at the same time? (clear, undistorted, full volume music through one channel only, left channel)" — In order to be thorough, bias voltage appeared the first time on one channel only. And clear music was produced through one channel only.
The DBT came on, then dimmed away as expected. At that point, sound came through one channel (left channel), but the other (right channel) was dead. It produced only a very low volume, highly distorted signal; although, the music was barely identifiable (it sounds like a bad input or output signal sounds, as though it should be easily addressed by checking external connections). The good, left channel produced sound, and showed .35v at the bias check with all inputs and outputs removed. It also showed 0.001DCmV offset. Then I went to check the bias on the other channel, which is when I discovered that it had no voltage — 0.01 DCmV. When I first powered up, I had an iPod connected to the input but used only one, sacrifical speaker at a time with which to check the two channels in sequence. It just happened that the speaker was initially connected to the left, good channel. I then switched it over to the right channel and discovered the lack of signal. It was at that point that I put my DMM on the bias check point and found no voltage.
Paying close attention, nothing 'blew' in a way that was either audible, smellable, or visually apparent, when I brought it up (just to clarify the terminology I got wrong regarding 'blown'). At that point, as far as I had gone, I would have judged the bring-up successful. That has remained the case since I later brought it up without the DBT. The only indication of a problem is that there is no voltage and bad signal coming from the right channel. A thorough visual inspection of the boards reveals nothing unusual or of interest I can discern. The overheated points on the board is a result of using braided copper to remove all the wires. I then cleaned the old solder off before re-stripping the wires and re-soldering all the connections. No such excessive heat was applied to any of the components or traces that connect them during the re-assembly. All of that was from de-soldering, and only at those connections at the edge of the board. Additionally, because of the problem I'm facing, I inspected each joint with a magnifying glass, then checked continuity between the boards and between the first component in line on each trace. Everything was and is working as expected.
To your other points, "It looks like the bolt AND the PEM are missing," what you are seeing in the photo is an optical illusion. Nothing was removed.
In regard to the question about soldering the TO-3s, during the first build, I did not solder the leads on the TO-3s. For the rebuild, following the replacement of the blown components, I reread all of Joe's material before proceeding. From that material, I concluded that soldering was an option, in the service of insuring secure, durable connections; therefore, I soldered this time for security purposes. If I misinterpreted the material, it's a simple matter to suck the solder off of the connections. I can't imagine what difference it makes, given that the C28 McIntosh preamp I rebuilt a couple years ago had soldered TO-3 leads from the factory (it's beautifully running my Series II 700). I just naturally assumed, perhaps incorrectly, that such installation was a good back-up measure. But then I obviously have much to learn.
As per Joe's material: "Allows either solder connection to the TO-3 Base and Emitter leads or slide-in, socketed connection to the Base and Emitter leads via the solder installation of precision, gold-plated socket cups into the Backplane boards.
"If TO-3 Transistor Base and Emitter leads are soldered directly into the plated through holes (instead of using the socket cup feature), generous hole clearance is provided to allow easy swap out for service, if required. By using either the direct solder method or socket cups, the Backplane boards eliminate the original low quality sockets and intermittent connections that are common with the original aging transistor sockets in PL400 amps. Extremely reliable output transistor connections.
"To remove a defective transistor, remove the 2 securing screws holding the transistor in. Place the amp on its back resting on the heat sink fins. USING 2 SOLDERING IRONS, evenly heat both the emitter and base lead. Once the solder re-flows, the transistor will drop out of its location."
Additionally, using my DMM, both bias transistors, left and right, read the same, with the negative probe on the base and the positive on the emitter and collector. I interpret that to mean the transistors are, at least, not blown or shorted.
Once again, if you got through this novel length post, I sincerely appreciate your assistance, and this lengthly response is an equally sincere attempt to clear up my miscommunications.
The DBT came on, then dimmed away as expected. At that point, sound came through one channel (left channel), but the other (right channel) was dead. It produced only a very low volume, highly distorted signal; although, the music was barely identifiable (it sounds like a bad input or output signal sounds, as though it should be easily addressed by checking external connections). The good, left channel produced sound, and showed .35v at the bias check with all inputs and outputs removed. It also showed 0.001DCmV offset. Then I went to check the bias on the other channel, which is when I discovered that it had no voltage — 0.01 DCmV. When I first powered up, I had an iPod connected to the input but used only one, sacrifical speaker at a time with which to check the two channels in sequence. It just happened that the speaker was initially connected to the left, good channel. I then switched it over to the right channel and discovered the lack of signal. It was at that point that I put my DMM on the bias check point and found no voltage.
Paying close attention, nothing 'blew' in a way that was either audible, smellable, or visually apparent, when I brought it up (just to clarify the terminology I got wrong regarding 'blown'). At that point, as far as I had gone, I would have judged the bring-up successful. That has remained the case since I later brought it up without the DBT. The only indication of a problem is that there is no voltage and bad signal coming from the right channel. A thorough visual inspection of the boards reveals nothing unusual or of interest I can discern. The overheated points on the board is a result of using braided copper to remove all the wires. I then cleaned the old solder off before re-stripping the wires and re-soldering all the connections. No such excessive heat was applied to any of the components or traces that connect them during the re-assembly. All of that was from de-soldering, and only at those connections at the edge of the board. Additionally, because of the problem I'm facing, I inspected each joint with a magnifying glass, then checked continuity between the boards and between the first component in line on each trace. Everything was and is working as expected.
To your other points, "It looks like the bolt AND the PEM are missing," what you are seeing in the photo is an optical illusion. Nothing was removed.
In regard to the question about soldering the TO-3s, during the first build, I did not solder the leads on the TO-3s. For the rebuild, following the replacement of the blown components, I reread all of Joe's material before proceeding. From that material, I concluded that soldering was an option, in the service of insuring secure, durable connections; therefore, I soldered this time for security purposes. If I misinterpreted the material, it's a simple matter to suck the solder off of the connections. I can't imagine what difference it makes, given that the C28 McIntosh preamp I rebuilt a couple years ago had soldered TO-3 leads from the factory (it's beautifully running my Series II 700). I just naturally assumed, perhaps incorrectly, that such installation was a good back-up measure. But then I obviously have much to learn.
As per Joe's material: "Allows either solder connection to the TO-3 Base and Emitter leads or slide-in, socketed connection to the Base and Emitter leads via the solder installation of precision, gold-plated socket cups into the Backplane boards.
"If TO-3 Transistor Base and Emitter leads are soldered directly into the plated through holes (instead of using the socket cup feature), generous hole clearance is provided to allow easy swap out for service, if required. By using either the direct solder method or socket cups, the Backplane boards eliminate the original low quality sockets and intermittent connections that are common with the original aging transistor sockets in PL400 amps. Extremely reliable output transistor connections.
"To remove a defective transistor, remove the 2 securing screws holding the transistor in. Place the amp on its back resting on the heat sink fins. USING 2 SOLDERING IRONS, evenly heat both the emitter and base lead. Once the solder re-flows, the transistor will drop out of its location."
Additionally, using my DMM, both bias transistors, left and right, read the same, with the negative probe on the base and the positive on the emitter and collector. I interpret that to mean the transistors are, at least, not blown or shorted.
Once again, if you got through this novel length post, I sincerely appreciate your assistance, and this lengthly response is an equally sincere attempt to clear up my miscommunications.
OK, so you never had the amp running. It needs to come apart. The PEM I saw as a problem, is the least of the worries now. That control board is in terrible shape. And, by cheaping out and not using the Phoenix connectors, you increased maintenance time by HOURS.
For ease of maintenance, especially for beginners DO NOT SOLDER YOUR OUTPUTS IN. If you have an issue, and have to disassemble the amp (Like in this instance), unsoldering all the outputs is a pain in the ass and should be avoided. Out of 100 amps I built, I NEVER have soldered in the outputs. That increases the amp disassembly by HOURS.
That amp is not worth troubleshooting until it's disassembled and all the quality issues are corrected. Look back at the builds of the back planes and control boards of all these builds documented for the last 10 years and if your boards don't resemble any of them (Solder Quality wise), it needs redoing. The other option you could have looked at was to buy Assembled Boards. Joe has them available as a time saver and also for challenged solderer's. Good soldering is the backbone of an an amplifier which will help it function correctly for the next 40 years.
Post a pic (A GOOD PIC) of the solder side of the control board (close up, not from 3 feet away).
For ease of maintenance, especially for beginners DO NOT SOLDER YOUR OUTPUTS IN. If you have an issue, and have to disassemble the amp (Like in this instance), unsoldering all the outputs is a pain in the ass and should be avoided. Out of 100 amps I built, I NEVER have soldered in the outputs. That increases the amp disassembly by HOURS.
That amp is not worth troubleshooting until it's disassembled and all the quality issues are corrected. Look back at the builds of the back planes and control boards of all these builds documented for the last 10 years and if your boards don't resemble any of them (Solder Quality wise), it needs redoing. The other option you could have looked at was to buy Assembled Boards. Joe has them available as a time saver and also for challenged solderer's. Good soldering is the backbone of an an amplifier which will help it function correctly for the next 40 years.
Post a pic (A GOOD PIC) of the solder side of the control board (close up, not from 3 feet away).
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No. Sorry. My mistake, again. After the DBT test, I unhooked it from the amp and then plugged the amp directly into an outlet. At that point, I tried to play music through the two channels. The left sounded great. After the right channel produced such terrible sound, I unhooked the speaker and the iPod and went about checking the bias. That's when I discovered the voltage issue. Before that, by virtue of just bad sound on the right channel, I assumed there was simply some connection that was weak and needed to be addressed. And that's where the things sits this minute, right in front of me. It does not, so far, appear that my staring at it is having any positive effect. What next?
"The overheated points on the board is a result of using braided copper to remove all the wires. I then cleaned the old solder off before re-stripping the wires and re-soldering all the connections."
I ONLY use solder wick. I do not own anything besides a little plastic solder sucker and my joints look NOTHING like that. That is from being in a hurry and not properly cleaning.
I ONLY use solder wick. I do not own anything besides a little plastic solder sucker and my joints look NOTHING like that. That is from being in a hurry and not properly cleaning.
Sounds like you missed some procedures. Most of us will leave it on the DBT and check that we are CLOSE to having the correct bias, and use that time for a little burn in. Since I can't follow what the hell you have done, I'm punching out. Don't forget to replace the bias transistor wires that are melted.
Notice how your output screws stick out to different lengths on the component side of the back plane board? That indicates to me that the PEM's are soldered with some down against the board (that would be correct), and some NOT soldered down to the board far enough. This can cause issues if the boards are not flat. Cracked joints, cracked boards, cracked traces...... Maybe some of your screws are loose but it doesn't appear correct. Post some pics of 1 of the left back plane, one of the right back plane, and one of BOTH sides of the control board making sure they are quality pics fairly close and NOT from 3 feet away.
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No, there isn't a problem with the screws. It's just that I use hundreds and hundreds of the things in some sprint car fabrications I do, and the ones I used on the TO=3s were from different batches. They vary in absolute length (which isn't critical for the units I produce) depending on what slave factory in China produces them for each order I make. Rest fully assured, the boards are secured evenly and to the correct torque specifications (literally, with a Vortex, optics torque wrench). There is no bending and certainly no breaking or cracking. The soldering was done after everything had been triple-checked and secured.