Marantz PM-32

harpon1 · 29th December 2011, 02:41 PM

Hi There to you all ,
I have a Marantz PM-32 which is giving me problems.
All the supplies seem present ,the tranistor outputs measure ok d.c wise
but doesn't have output audio either chanel .
I have taken the bottom off and it had some dry joints on a couple
of transistors near the bridge rec they are D2037 and B1357 and the
board is discoloured due to heat.
The power LED come on sometime but is intermittent.
It would be good to get a circuit diagram , can anybody help please?

Regards
Steve

Coconuts 500 · 29th December 2011, 07:15 PM

Do you hear a relay click a few seconds after power up?

jaycee · 30th December 2011, 12:43 AM

If there is no relay click, it is likely one of those transistors has failed - they act as regulators to produce +23v and -16v supplies. The protection circuit operates from these supplies, so if one is missing, the amp will remain in protect mode.

Pretty much any decent TO-220 transistor will work in place of the D2037/B1357 devices. TIP31A/TIP32A should replace them adequately. If you can fit heatsinks to them, even better.

harpon1 · 30th December 2011, 01:40 PM

Thanks guys ,
I checked the relay and it's not clicking over and the signal goes in but not out.
So the transistors that operates this I suppose have gone faulty.
But finding a D2037 and B1357 is going to be a problem.
CPC is no ,RS no, Farnell is no .

jaycee · 31st December 2011, 04:29 AM

You probably won't be able to get them. They were originally made by Rohm, but seem to be long discontinued.

As I said in my post above, they are only used as regulators, so they aren't critical. The TIP31A/TIP32A will do the same job.

29th December 2011, 02:41 PM	#1
harpon1 diyAudio Member Join Date: Dec 2011	Marantz PM-32 Hi There to you all , I have a Marantz PM-32 which is giving me problems. All the supplies seem present ,the tranistor outputs measure ok d.c wise but doesn't have output audio either chanel . I have taken the bottom off and it had some dry joints on a couple of transistors near the bridge rec they are D2037 and B1357 and the board is discoloured due to heat. The power LED come on sometime but is intermittent. It would be good to get a circuit diagram , can anybody help please? Regards Steve

30th December 2011, 01:40 PM	#4
harpon1 diyAudio Member Join Date: Dec 2011	Marrantz PM-32 Thanks guys , I checked the relay and it's not clicking over and the signal goes in but not out. So the transistors that operates this I suppose have gone faulty. But finding a D2037 and B1357 is going to be a problem. CPC is no ,RS no, Farnell is no .

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29th December 2011, 07:15 PM	#2
Coconuts 500 diyAudio Member Join Date: Apr 2010	Do you hear a relay click a few seconds after power up?

30th December 2011, 12:43 AM	#3
jaycee diyAudio Member Join Date: Apr 2004 Location: Norwich, UK	If there is no relay click, it is likely one of those transistors has failed - they act as regulators to produce +23v and -16v supplies. The protection circuit operates from these supplies, so if one is missing, the amp will remain in protect mode. Pretty much any decent TO-220 transistor will work in place of the D2037/B1357 devices. TIP31A/TIP32A should replace them adequately. If you can fit heatsinks to them, even better.

31st December 2011, 04:29 AM	#5
jaycee diyAudio Member Join Date: Apr 2004 Location: Norwich, UK	You probably won't be able to get them. They were originally made by Rohm, but seem to be long discontinued. As I said in my post above, they are only used as regulators, so they aren't critical. The TIP31A/TIP32A will do the same job.

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