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Old 29th March 2008, 06:07 PM   #11
manina is offline manina  Germany
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Quote:
Originally posted by DCPreamp
If the amp works, then don't worry about the rectifiers.

<cut>


I'll see if I can post the 952 schematics later. I just replied to a post on a 2002 amp in this forum a bit earlier.
Actually, the amp does not work at its best. When I turn it on, it has a metallic sound
however after 10-15 minute of work it sounds as it should be.

I targeted the rectifier hoping it was it as it' a pretty easy job to replace this one but if you say it' either working or not, I have to come back to the first option: caps to be replaced


If you have also the 5002iq schematic will ge great
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Old 30th March 2008, 04:43 AM   #12
shagone is offline shagone  United States
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maybe if you simply replace most of the larger electrolytic capacitors and resolder any bad looking connections it would come back to life. it's worth a shot!
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Old 1st April 2008, 04:54 AM   #13
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Here are the 1502 amplifier schematics. The power supply will follow.

As far as the "metal" sound, I'd need to see the waveforms to diagnose it. I still don't think it's the rectifiers, and doubt it's the caps either. It may be the bias circuit: It could be running a real harsh class 'B' until the amp warms up to A/B.
Attached Files
File Type: pdf page023.pdf (57.3 KB, 48 views)
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Old 1st April 2008, 04:56 AM   #14
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Power supply schematics.
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File Type: pdf page022.pdf (48.6 KB, 39 views)
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Old 1st April 2008, 12:23 PM   #15
manina is offline manina  Germany
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Quote:
Originally posted by DCPreamp
Here are the 1502 amplifier schematics. The power supply will follow.

As far as the "metal" sound, I'd need to see the waveforms to diagnose it. I still don't think it's the rectifiers, and doubt it's the caps either. It may be the bias circuit: It could be running a real harsh class 'B' until the amp warms up to A/B.

Thanks for the PDF (all you posted ).

I'm not able to provide the waveforms - don't have the equipment for this.

As long as it's a matter of replacing caps I can do it by myslef - I'll have to find a good technician to adjust the bias.
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Old 3rd January 2009, 12:42 PM   #16
manina is offline manina  Germany
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Default work almost done

It has been a while since the last post. I finally managed to have time to work on this amp

Changed all electrolites caps, fixed some soldering (especially at the rele side) and changed the power cables with longer/bigger ones.

I also moved the trimmer to regulate the polarization and finally the amp works great.

How can I fine tune the polarization? I did it "by ears" - slighlty turned untill it sounded better hower I understand this is not the best method; any suggestion?
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