Transformer sounds as if it is fine.
Try some 5 minute epoxy!!
Once you have the unit apart many people suggest to replace the old electrolytic caps with new ones.Also the trimmer R can cause troubles as well.
As for the big ecaps, C3-4. well at least look for any leakage or bulging.
Looks as if someones been at Q19(2SA810) by the mess of thermal compound.
I see some trany's pkgs, that I have never seen before.
See if you can get hold of "markthefixer" at audiokarma.org, to see if he knows of this model.
Try some 5 minute epoxy!!
Once you have the unit apart many people suggest to replace the old electrolytic caps with new ones.Also the trimmer R can cause troubles as well.
As for the big ecaps, C3-4. well at least look for any leakage or bulging.
Looks as if someones been at Q19(2SA810) by the mess of thermal compound.
I see some trany's pkgs, that I have never seen before.
See if you can get hold of "markthefixer" at audiokarma.org, to see if he knows of this model.
Pcb update
I finished disassemble the amp, in order to identify any problem I spent some times cleaning the pcb and polish the silver connections.
I found 3 problems (marked in red in the next picture) 2 components are not original and there is an extra resistor. Any help on that?
At an eye inspection all the components and the pcd are fine but I will check with a mutlimeter all the restistors and diodes tomorrow.
As you guys can see I removed all the caps and I started mounting some new ones (elna, nichicon) as suggested. Should I also emove the caps like the one market in green in the picture?
I found most of the caps but I have a couple of problems:
- I need to substitue two radial caps 100V 470uf but I can't find something similar, max dimensions 25mm x 50mm. (could be snap in without problems)
The only thing close that I found is 680uf 100V from RDE, can I use those?
- I can't test the 33000uf 80V caps, but after 40 years I don't expect more than 30/40% out of them. I found two substitutes 1 , 2 they are perfectly similar in dimensions to mine but unfortunately they will be in stock in 17 weeks
If someone know where I can find a couple of those caps please let me know
I finished disassemble the amp, in order to identify any problem I spent some times cleaning the pcb and polish the silver connections.
I found 3 problems (marked in red in the next picture) 2 components are not original and there is an extra resistor. Any help on that?
At an eye inspection all the components and the pcd are fine but I will check with a mutlimeter all the restistors and diodes tomorrow.
As you guys can see I removed all the caps and I started mounting some new ones (elna, nichicon) as suggested. Should I also emove the caps like the one market in green in the picture?
I found most of the caps but I have a couple of problems:
- I need to substitue two radial caps 100V 470uf but I can't find something similar, max dimensions 25mm x 50mm. (could be snap in without problems)
The only thing close that I found is 680uf 100V from RDE, can I use those?
- I can't test the 33000uf 80V caps, but after 40 years I don't expect more than 30/40% out of them. I found two substitutes 1 , 2 they are perfectly similar in dimensions to mine but unfortunately they will be in stock in 17 weeks
If someone know where I can find a couple of those caps please let me know
An externally hosted image should be here but it was not working when we last tested it.
Transformer
I finished repairing the transformer. The borders are not all perfectly aligned but is surely better than the beginning. I couldn't repair the upper left corner, for don't damaging the transformer I didn't use an hammer or direct hit but just a vise. I also reinstalled the nuts, the result is not really nice to see but it's perfectly working.
I will do the rewirng as soon as I finish substitute all caps in the pcb
I finished repairing the transformer. The borders are not all perfectly aligned but is surely better than the beginning. I couldn't repair the upper left corner, for don't damaging the transformer I didn't use an hammer or direct hit but just a vise. I also reinstalled the nuts, the result is not really nice to see but it's perfectly working.
I will do the rewirng as soon as I finish substitute all caps in the pcb
An externally hosted image should be here but it was not working when we last tested it.
Hmmm.... I hope you made notes of how it all re-connects back together
If I'm honest, its not the way I would have approached this but what's done is done. I would have preferred (at least initially) in seeing what the original problems were before dismantling it so completely. The opportunities for error in reassembly and parts replacement are very real.
The extra resistor. You will have to identify the component reference number in question from the PCB layouts in the manual.
680uf in place of 470uf is probably fine, again, giving the component reference so we can see its function in the circuit would help.
The transistors mounted on wires off the PCB are probably the vbe generator (bias) for the output stage.
Unless proved faulty I wouldn't discount the 33000 uf caps as being a problem at this stage.
If I'm honest, its not the way I would have approached this but what's done is done. I would have preferred (at least initially) in seeing what the original problems were before dismantling it so completely. The opportunities for error in reassembly and parts replacement are very real.
The extra resistor. You will have to identify the component reference number in question from the PCB layouts in the manual.
680uf in place of 470uf is probably fine, again, giving the component reference so we can see its function in the circuit would help.
The transistors mounted on wires off the PCB are probably the vbe generator (bias) for the output stage.
Unless proved faulty I wouldn't discount the 33000 uf caps as being a problem at this stage.
I think looking for suitable replacement transistors will be next on the list and that probably means using different package outlines to those on the PCB as they will be well and truly obsolete.
You also need to check all the low value resistors (particularly those wirewounds)
All that is for another day
You also need to check all the low value resistors (particularly those wirewounds)
All that is for another day
Hmmm.... I hope you made notes of how it all re-connects back together
If I'm honest, its not the way I would have approached this but what's done is done. I would have preferred (at least initially) in seeing what the original problems were before dismantling it so completely. The opportunities for error in reassembly and parts replacement are very real.
The extra resistor. You will have to identify the component reference number in question from the PCB layouts in the manual.
680uf in place of 470uf is probably fine, again, giving the component reference so we can see its function in the circuit would help.
The transistors mounted on wires off the PCB are probably the vbe generator (bias) for the output stage.
Unless proved faulty I wouldn't discount the 33000 uf caps as being a problem at this stage.
Two of the wires needed for the transformer were hidden in the front part of the amp. In order to access this zone I had to disassemble since I couldn't connect the transformer without doing so.
In order to reduce future problems I took many pictures and I numbered all the cables with the corresponding connection on the pcb plus I divided the screws by zones, I hope that will help.
My next step will be to substitute all the small caps and reistall the power supply section with the transformer
- The 100V 470uf are C11 and C12 in the power supply pcb
- The extra resistor is mouted at R31 2.2K on the power amp pcb
- The original transistor is an hitachi 2sc281, the one in the picture has no print, they only thing I know is that it's a little bit smaller than the hitachi
I think looking for suitable replacement transistors will be next on the list and that probably means using different package outlines to those on the PCB as they will be well and truly obsolete.
You also need to check all the low value resistors (particularly those wirewounds)
All that is for another day
with "those on the PCB" do you mean just Q7-8-10-18-19 or all the transtistors?
You originally showed a pics of one of the heatsinks, with sub transistors, was this matched with the pcb as shown, that had the work done on it (messy transistor)?
If so, when you should re-assemble by starting with the PA pcb and outputs that look as if they were not touched.
I strongly suggest to re-assemble the PS first, (especially since the transformer has been messed with) test, before adding any of the other pcb's. Start with just the transformer, big filter ecaps, no power supply pcb, test the transformer/main ecap DC is okay, then the power supply pcb, test. If PS okay proceed with the buffer,protect, meter pcb's more test. Then finally start with only one PA channel first, the one that looks as if it was original, step by step. I really ? doing a blanket trany sub at this point in time. Could use only one set of o/p trany (old/original spec'd ones if you can find a good set), just to check biasing first. You DO NOT want to do a complete re-assembly with out some intermediate steps or you can be wasting a lot of money on new parts. (Magic White Smoke)
Good luck
Rick
If so, when you should re-assemble by starting with the PA pcb and outputs that look as if they were not touched.
I strongly suggest to re-assemble the PS first, (especially since the transformer has been messed with) test, before adding any of the other pcb's. Start with just the transformer, big filter ecaps, no power supply pcb, test the transformer/main ecap DC is okay, then the power supply pcb, test. If PS okay proceed with the buffer,protect, meter pcb's more test. Then finally start with only one PA channel first, the one that looks as if it was original, step by step. I really ? doing a blanket trany sub at this point in time. Could use only one set of o/p trany (old/original spec'd ones if you can find a good set), just to check biasing first. You DO NOT want to do a complete re-assembly with out some intermediate steps or you can be wasting a lot of money on new parts. (Magic White Smoke)
Good luck
Rick
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For output transitors, take a look at pioneer sa-9900. 2sc1079 transistor [Archive] - AudioKarma.org Home Audio Stereo Discussion Forums
Motorola make a good replacement.
Motorola make a good replacement.
A badly injured Exclusive M3 [Archive] - AudioKarma.org Home Audio Stereo Discussion Forums
If you are patient, you can ask "markthefixer" at audiokarma, he is very good at working folks through this exercise as long as you follow his instructions. He knows his Pioneer stuff better than I.
If you are patient, you can ask "markthefixer" at audiokarma, he is very good at working folks through this exercise as long as you follow his instructions. He knows his Pioneer stuff better than I.
C11 and C12 will be fine as 680/100 caps.
R31 is part of the Vbe generator. Adding a resistor across R31 would reduce the maximum bias available as the preset is turned. Its hard to say whether that has been added as part of the botched repair or whether it was fitted during manufacture. Manufacturer alterations like that are quite common on older gear.
Q11 is the actual Vbe generator and would be in thermal contact with the heatsink to track temperature changes.
A very real problem could be finding replacements for the T066 package devices (the drivers 2SA483/2SC783), assuming they are faulty, although I think it probably wise to replace these whatever. It would almost certainly mean fitting a T0126 style device and insulating kit as a replacement.
Testing the PSU and all the regulated outputs is the first step.
R31 is part of the Vbe generator. Adding a resistor across R31 would reduce the maximum bias available as the preset is turned. Its hard to say whether that has been added as part of the botched repair or whether it was fitted during manufacture. Manufacturer alterations like that are quite common on older gear.
Q11 is the actual Vbe generator and would be in thermal contact with the heatsink to track temperature changes.
A very real problem could be finding replacements for the T066 package devices (the drivers 2SA483/2SC783), assuming they are faulty, although I think it probably wise to replace these whatever. It would almost certainly mean fitting a T0126 style device and insulating kit as a replacement.
Testing the PSU and all the regulated outputs is the first step.
Thanks for the hint, I will try to contact him as soon as audiokarma reopen registration.
Resistors
I tested all the resistors but I found that many are not working as they should (evidentiated with a red circle)
Before start testing should I change the ones on the power supply or I can skip the resistors for now?
I tested all the resistors but I found that many are not working as they should (evidentiated with a red circle)
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Before start testing should I change the ones on the power supply or I can skip the resistors for now?
You are running ahead of yourself...
Why do you think they are all faulty ?
You can only correctly check resistors out of circuit. I would be amazed if any (other than perhaps the really low value ones around the output stage) were damaged/faulty/open.
I just worry that you are not going to get a good result from all this. Its a complex amplifier and one that needs the correct approach to fixing it.
You keep getting advice (on here) to go to another forum and if that is what you want to do then that's fine but this random approach to fixing the amp isn't going to work.
Why do you think they are all faulty ?
You can only correctly check resistors out of circuit. I would be amazed if any (other than perhaps the really low value ones around the output stage) were damaged/faulty/open.
I just worry that you are not going to get a good result from all this. Its a complex amplifier and one that needs the correct approach to fixing it.
You keep getting advice (on here) to go to another forum and if that is what you want to do then that's fine
but this random approach to fixing the amp isn't going to work.Molly is correct on all accounts. Between the both of us we can give you some guidance and possibly resurrect the beast. If you decide to carry out your task heeding our advice well good luck to you.
Resistors measurements? Probably bad connections due to oxidized leads.Instrumentation? Pilot Error?
TO-66 subs? A TO-220 with leads folded down at the right spot, so that the tab hole lines up with one of the TO-66 holes and leads lining up, chop the middle lead, can be made to work in some cases. Note, have to check polarities, EBC?
I provide audiokarma as a source of information.since they have a dedicated Pioneer forum, not necessarilly to steer people over there. A good % of the members are not very technical at all & I laugh at the nonsense that circulates. This is why I like this site because there as so many experienced EE types on this site.
Here are a few handy thoughts you should have in mind:
1) The Pioneer M3 is one of the best amps Pioneer has ever made and you should approach this project with this in mind. In particular, it is safe to assume better minds than ours and yours have put it together so before any changes, stop and think and examine and learn until you understand. Also of note is that it's worth quite a bit of money even in this state, which also means it is well worth saving. I can pretty much guarantee it's going to surprise you in a positive way if you put it together properly,as it deserves.
2) This amp has been through the hands of at least one incompetent fool, and no, I am not going to mince words, this was a FOOL. As you have seen yourself, taking out the transformer is a matter of removing 4 screws, yet this idiot had to bend and break the case because he was lazy enough not to turn the thing around and see the screws. I'm not even going to strat on the cut wires. And, any justification for even looking at the transformer - this is what measurement is for. Keep this in mind, you have a huge job before you because of this fool, firstly to undo the 'fixes' he put in. In this regard you will be looking at more money to be spent on this beast. In particular:
- don't bother with the output transistors. Throw them away, you can't trust them. Obviosuly the output stage has been destroyed at least once and when that happens the only sure way to fix it properly id to replace the entire set of outputs. Also, it's not uncommon to replace the drivers but in this case you may have a problem as finding TO66 cased driver transistors (let alone original parts) is pretty much like trying to find hen's teeth. IF they test good, you may be able to trust them.
- Most small caps expecially around other hot parts should be changed for new ones. Keep in mind they put in the best they had then, and therefore respect that and try to match part quality.
- Don't make assumptions about the state of the big filter caps, it depends how the amp was used, but in these top of the line devices, they used the best parts they could find. It's not that uncommon to find the measured values exactly as specified. However, if you have the money and time, and really want to do a proper restauration, then replace them, again, respecting parts quality.
- DO NOT measure parts in-circuit. You will not get the right values. This is not a tube circuit where a tube can easily be removed or at any rate with n opower it becomes open-circuit and does not influencee masurements. That being said, your best ally is your eyes. If anything looks burnt or cracked or damaged, it's a good idea to check and replace. Some parts may require replacement even so - one good candidate are tantalum capacitors. Old types used to go short in-circuit for no reason, only to innocently measure properly once tested. Others include certain types of diodes (usually multi-junction, they look like a small colored ball with thin wires coming out), silver-mica caps (so called black flag types, they look like small 1cm squares dipped in black resin).
- Carefully clean, then inspect all solder joints. You may find many need re-doing and often a careful re-solder is a good idea (but be sure you know what you are doing, it's not a matter of just adding more fresh solder). CAREFUL! Even though this is made on FR4 material (epoxy) which was then cutting edge and expensive, it's not as stable as todays versions. The PCB tracks may be fragile and may come off the board if you are not careful. BTW use of epoxy base is a big clue that you are looking at a no-compromise top-of-the-line high end amp. VERY few amps used it in those times, and they usually cost like a good car.
There are many people here who are very knowledgeable and have tons of experience resurrecting amps that were even worse off than yours. Feel free to ask, but be patient - this is not a job for anyone who is not.
One personal opinion, I don't think your transformer fix will last. It is after all very heavy. Also, one thing you should have done before applying the putty or resin is to replace the cut wires with new ones (by extending tham 'inside the box'). You might want to look at special nuts that are used for carpentry, these have a flared extension with 3 or 4 needle-like extensions on them that normally are pressed into the wood. Another part looks like a tube with a larger thread on the outside, which is normally screwed into the wood but in your case would hold itself inside the resin. You may also consider carefully boring out the existing ones and replacing them with something like I just described or just new ones and re-potting the whole thing with a fresh layer of resin.
One final transformer thought: when connecting the transformer to test it, leave it on for a while, at least 10 minutes, and check for heat. With no load it should remain cold. The slightly higher voltages you are seeing are normal since there is no load and the mains is 230V whereas the transformer was specced for 220V.
PS you can use a hammer, just be very careful and don't hit the case directly, rather througha piece of wood, or use a plastic or wooden hammer.
1) The Pioneer M3 is one of the best amps Pioneer has ever made and you should approach this project with this in mind. In particular, it is safe to assume better minds than ours and yours have put it together so before any changes, stop and think and examine and learn until you understand. Also of note is that it's worth quite a bit of money even in this state, which also means it is well worth saving. I can pretty much guarantee it's going to surprise you in a positive way if you put it together properly,as it deserves.
2) This amp has been through the hands of at least one incompetent fool, and no, I am not going to mince words, this was a FOOL. As you have seen yourself, taking out the transformer is a matter of removing 4 screws, yet this idiot had to bend and break the case because he was lazy enough not to turn the thing around and see the screws. I'm not even going to strat on the cut wires. And, any justification for even looking at the transformer - this is what measurement is for. Keep this in mind, you have a huge job before you because of this fool, firstly to undo the 'fixes' he put in. In this regard you will be looking at more money to be spent on this beast. In particular:
- don't bother with the output transistors. Throw them away, you can't trust them. Obviosuly the output stage has been destroyed at least once and when that happens the only sure way to fix it properly id to replace the entire set of outputs. Also, it's not uncommon to replace the drivers but in this case you may have a problem as finding TO66 cased driver transistors (let alone original parts) is pretty much like trying to find hen's teeth. IF they test good, you may be able to trust them.
- Most small caps expecially around other hot parts should be changed for new ones. Keep in mind they put in the best they had then, and therefore respect that and try to match part quality.
- Don't make assumptions about the state of the big filter caps, it depends how the amp was used, but in these top of the line devices, they used the best parts they could find. It's not that uncommon to find the measured values exactly as specified. However, if you have the money and time, and really want to do a proper restauration, then replace them, again, respecting parts quality.
- DO NOT measure parts in-circuit. You will not get the right values. This is not a tube circuit where a tube can easily be removed or at any rate with n opower it becomes open-circuit and does not influencee masurements. That being said, your best ally is your eyes. If anything looks burnt or cracked or damaged, it's a good idea to check and replace. Some parts may require replacement even so - one good candidate are tantalum capacitors. Old types used to go short in-circuit for no reason, only to innocently measure properly once tested. Others include certain types of diodes (usually multi-junction, they look like a small colored ball with thin wires coming out), silver-mica caps (so called black flag types, they look like small 1cm squares dipped in black resin).
- Carefully clean, then inspect all solder joints. You may find many need re-doing and often a careful re-solder is a good idea (but be sure you know what you are doing, it's not a matter of just adding more fresh solder). CAREFUL! Even though this is made on FR4 material (epoxy) which was then cutting edge and expensive, it's not as stable as todays versions. The PCB tracks may be fragile and may come off the board if you are not careful. BTW use of epoxy base is a big clue that you are looking at a no-compromise top-of-the-line high end amp. VERY few amps used it in those times, and they usually cost like a good car.
There are many people here who are very knowledgeable and have tons of experience resurrecting amps that were even worse off than yours. Feel free to ask, but be patient - this is not a job for anyone who is not.
One personal opinion, I don't think your transformer fix will last. It is after all very heavy. Also, one thing you should have done before applying the putty or resin is to replace the cut wires with new ones (by extending tham 'inside the box'). You might want to look at special nuts that are used for carpentry, these have a flared extension with 3 or 4 needle-like extensions on them that normally are pressed into the wood. Another part looks like a tube with a larger thread on the outside, which is normally screwed into the wood but in your case would hold itself inside the resin. You may also consider carefully boring out the existing ones and replacing them with something like I just described or just new ones and re-potting the whole thing with a fresh layer of resin.
One final transformer thought: when connecting the transformer to test it, leave it on for a while, at least 10 minutes, and check for heat. With no load it should remain cold. The slightly higher voltages you are seeing are normal since there is no load and the mains is 230V whereas the transformer was specced for 220V.
PS you can use a hammer, just be very careful and don't hit the case directly, rather througha piece of wood, or use a plastic or wooden hammer.
Last edited:
You are running ahead of yourself...
Why do you think they are all faulty ?
You can only correctly check resistors out of circuit. I would be amazed if any (other than perhaps the really low value ones around the output stage) were damaged/faulty/open.
I just worry that you are not going to get a good result from all this. Its a complex amplifier and one that needs the correct approach to fixing it.
You keep getting advice (on here) to go to another forum and if that is what you want to do then that's fine
Sorry I know it look like I'm not following instructions but I asked the question about resistors since I was going to assemble the amp and I didn't know if I should wait or not. Sometimes I get lost in a glass of water while I should just follow instructions.
I think it will take me 1 hour to put the power supply and transformer back in, I will post an update as soon as I finish and before start testing
Thanks for all the good infos, actually I managed to assemble the amp back but the transformer don't fit properly. So I will remove the resin I used and I will spend some more time fixing the borders.
I will look for those special nuts and I will try to find a better resin. In this case I have two options, I can either look for the resin used in boats manufacturing or I can ask directly to a transformer factory if they could give me some of the resin they use.
By the way since I didn't metion it before, for this particular project I have no budget limit. I'm well aware that this was an exceptional amp and my goal is to do a "perfect" restauration.
For what I know at that time my father went directly to pioneer headquarters in ortder to buy this amp since just a few were imported to europe. The actual complete system that I'm trying to rebulid is compose of C3+M3+JBL4333, they only part not working is the M3
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