Sansui AU-2900 (Worth buying faulty + service manual?)

bleachershane · 18th April 2011, 09:13 PM

Got a chance of a Sansui AU-2900 at around £30 with the following fault...
"The item powers up and works but the sound output is distorted. In very good condition with some marks from general use. Please review the photos above for more details."

Worth purchasing? Trying to track a schematic/service manual before putting down the cash but nothing on the net as far as I can find... Have downloaded the service manual for the AU-3900 in the assumption that it's similar...

Finished restoring my faulty Cyrus 2, so looking for another ailing amplifier to bring back to life (I actually enjoy it...!) so worth a punt? Never heard a Sansui but heard good things. And never worked on an amp this old (mid-70s?)...

Any help gratefully received!

aparatusonitus · 18th April 2011, 09:44 PM

I can supply a full service manual...Send me a pm with your private email, and I will send tomorow morning...

bleachershane · 18th April 2011, 09:46 PM

Would be very grateful, shall PM you my email.

Any chance you've had experience with one? Worth working on?

DigitalJunkie · 18th April 2011, 10:46 PM

I'd do it,but I'm partial to Sansui gear...so.

aparatusonitus · 19th April 2011, 05:15 AM

Quote:

Originally Posted by bleachershane

Any chance you've had experience with one? Worth working on?

No, I've no experience with Sansui, but judging from schematic I would expect old, easy going sound...perfect for casual listening or 2nd system. Also, the amp IS working (with distortion), so should be easy fix I think. It does looks good for not much stash...I would pick it.

digits · 19th April 2011, 05:25 AM

Ah yes, lovely amps, their bias drifts a bit over the years, a quick adjustment of trimpots and they are good to go.

bleachershane · 19th April 2011, 06:42 AM

Might give them a punt, just for a repair project.

Distortion on both channels, hmm, of course tackle all the electrolytics, check supplies, clean out all switches and pots, set up the bias (I had a feeling they'd probably drift a fair bit in the last 35 years!), then go onto possible leaky diodes? Going down the right path?

aparatusonitus, they are supposed to be quite warm sounding, and judging from the specs of the power transistors it would point me to that conclusion too...

digits · 19th April 2011, 07:16 AM

I'm willing to bet good money its just the bias setting, I've serviced 2 old 30+ year sansuis, both had the same problem, even though they were not the same model.

bleachershane · 19th April 2011, 08:36 AM

Quote:

Originally Posted by digits

I'm willing to bet good money its just the bias setting, I've serviced 2 old 30+ year sansuis, both had the same problem, even though they were not the same model.

I'm interested now to see if it is bias issue... on searching the internet there seems to be a trend of various old Sansuis with distorted channels.

mikstick · 1st May 2011, 06:08 PM

how did you get on with it Bleachershane?

18th April 2011, 09:13 PM	#1
bleachershane diyAudio Member Join Date: Jun 2008 Location: Glasgow, Scotland	Sansui AU-2900 (Worth buying faulty + service manual?) Got a chance of a Sansui AU-2900 at around £30 with the following fault... "The item powers up and works but the sound output is distorted. In very good condition with some marks from general use. Please review the photos above for more details." Worth purchasing? Trying to track a schematic/service manual before putting down the cash but nothing on the net as far as I can find... Have downloaded the service manual for the AU-3900 in the assumption that it's similar... Finished restoring my faulty Cyrus 2, so looking for another ailing amplifier to bring back to life (I actually enjoy it...!) so worth a punt? Never heard a Sansui but heard good things. And never worked on an amp this old (mid-70s?)... Any help gratefully received! __________________ "If only we'd known that iPods would unite to enslave the people they entertained."

18th April 2011, 09:44 PM	#2
aparatusonitus diyAudio Member Join Date: Jan 2004 Location: Split, Croatia	I can supply a full service manual...Send me a pm with your private email, and I will send tomorow morning... __________________ Non é mai abbastanza...

18th April 2011, 09:46 PM	#3
bleachershane diyAudio Member Join Date: Jun 2008 Location: Glasgow, Scotland	Would be very grateful, shall PM you my email. Any chance you've had experience with one? Worth working on? __________________ "If only we'd known that iPods would unite to enslave the people they entertained."

19th April 2011, 06:42 AM	#7
bleachershane diyAudio Member Join Date: Jun 2008 Location: Glasgow, Scotland	Might give them a punt, just for a repair project. Distortion on both channels, hmm, of course tackle all the electrolytics, check supplies, clean out all switches and pots, set up the bias (I had a feeling they'd probably drift a fair bit in the last 35 years!), then go onto possible leaky diodes? Going down the right path? aparatusonitus, they are supposed to be quite warm sounding, and judging from the specs of the power transistors it would point me to that conclusion too... __________________ "If only we'd known that iPods would unite to enslave the people they entertained."

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18th April 2011, 10:46 PM	#4
DigitalJunkie diyAudio Member Join Date: Apr 2003 Location: Portland,Oregon Blog Entries: 4	I'd do it,but I'm partial to Sansui gear...so.

19th April 2011, 05:25 AM	#6
digits diyAudio Member Join Date: Apr 2011	Ah yes, lovely amps, their bias drifts a bit over the years, a quick adjustment of trimpots and they are good to go.

19th April 2011, 07:16 AM	#8
digits diyAudio Member Join Date: Apr 2011	I'm willing to bet good money its just the bias setting, I've serviced 2 old 30+ year sansuis, both had the same problem, even though they were not the same model.

1st May 2011, 06:08 PM	#10
mikstick diyAudio Member Join Date: May 2011 Location: liverpool, UK	how did you get on with it Bleachershane?

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