Sansui AU-9500 trouble

markmlists · 10th May 2007, 06:49 AM

Hi,

Need assistance about my recently acquired au9500. I bought this last week after many years of storage.

Last Night, after playing at low volume for about 3 hours, my todler accidentally turned the volume knob to about midway increasing the volume substantially. By the time I reached it, something in the unit popped causing the power to cut off with a white smoke (unburnt smell, fuse glass is not black-the filament just cut).

Troubleshooting done:

1. Upong closer inspection, one the left speaker fuse blew (one of 4. Main fuse is ok).
2. I checked the top of the unit cover off and there was nothing that was discolored.
3. I then removed the bottom cover and saw 1 3.3uf 100V electrolytic busted (guts out cut in half). This capacitor is connected to one of the terminals of the driver board socket.
4. I checked all the diodes and capacitors there and they seemed ok. I dont know how to check the 2 VR's though.

Questions:

1. Is this just a case of dried-long stored caps shorting out because of the sudden increase in volume and replacing them along with the fuse would fix the problem?

2. Is it just a dc filtering cap (they have 2 of those caps per channel-at the bottom of the unit)? If it is a dc filtering cap, can I replace them with non polar types (film caps or non polar electrolytic)?

3. Can I increase the value of this cap to higher voltage?

4. Any troubleshooting steps you could suggest is appreciated.

Many Thanks!!!

Mark

Netlist · 10th May 2007, 07:08 AM

Mark,
No doubt more help could be given if a schematic was at hand.
eserviceinfo.com has it. Try to get it and return here with part numbers.

/Hugo

steve_v · 24th May 2007, 05:34 AM

I would first do the obvious and replace the caps, they will be pretty cheap.

I have the full operation / service manual, but I don't know what the scan quality would be like as it is a photocopy of a photocopy...

Cheers,

Steve.

Cloth Ears · 24th May 2007, 06:04 AM

Sansui forum.

markmlists · 24th May 2007, 08:22 AM

Thanks for the input guys. I replaced the caps then bought it to a tech for further troubleshooting and opt replacement. Its now sounding well now. I read 1 article in audiokarma about a similar problem but cant ask/post as registration is not allowed for now. 1 kind soul sent me a schmatic and will review further to troubleshoot more if needed to avoid it happening again. . will keep you guys posted. thanks

10th May 2007, 06:49 AM	#1
markmlists diyAudio Member Join Date: Feb 2006 Location: Manila	Sansui AU-9500 trouble Hi, Need assistance about my recently acquired au9500. I bought this last week after many years of storage. Last Night, after playing at low volume for about 3 hours, my todler accidentally turned the volume knob to about midway increasing the volume substantially. By the time I reached it, something in the unit popped causing the power to cut off with a white smoke (unburnt smell, fuse glass is not black-the filament just cut). Troubleshooting done: 1. Upong closer inspection, one the left speaker fuse blew (one of 4. Main fuse is ok). 2. I checked the top of the unit cover off and there was nothing that was discolored. 3. I then removed the bottom cover and saw 1 3.3uf 100V electrolytic busted (guts out cut in half). This capacitor is connected to one of the terminals of the driver board socket. 4. I checked all the diodes and capacitors there and they seemed ok. I dont know how to check the 2 VR's though. Questions: 1. Is this just a case of dried-long stored caps shorting out because of the sudden increase in volume and replacing them along with the fuse would fix the problem? 2. Is it just a dc filtering cap (they have 2 of those caps per channel-at the bottom of the unit)? If it is a dc filtering cap, can I replace them with non polar types (film caps or non polar electrolytic)? 3. Can I increase the value of this cap to higher voltage? 4. Any troubleshooting steps you could suggest is appreciated. Many Thanks!!! Mark

24th May 2007, 06:04 AM	#4
Cloth Ears diyAudio Member Join Date: Dec 2001 Location: Melbourne, Australia	Sansui forum. __________________ Jont. "It is impossible to build a fool proof system; because fools are so ingenious."

24th May 2007, 08:22 AM	#5
markmlists diyAudio Member Join Date: Feb 2006 Location: Manila	thanks Thanks for the input guys. I replaced the caps then bought it to a tech for further troubleshooting and opt replacement. Its now sounding well now. I read 1 article in audiokarma about a similar problem but cant ask/post as registration is not allowed for now. 1 kind soul sent me a schmatic and will review further to troubleshoot more if needed to avoid it happening again. . will keep you guys posted. thanks

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10th May 2007, 07:08 AM	#2
Netlist diyAudio Moderator Join Date: Jan 2003	Mark, No doubt more help could be given if a schematic was at hand. eserviceinfo.com has it. Try to get it and return here with part numbers. /Hugo

24th May 2007, 05:34 AM	#3
steve_v diyAudio Member Join Date: Sep 2004 Location: Dunedin	I would first do the obvious and replace the caps, they will be pretty cheap. I have the full operation / service manual, but I don't know what the scan quality would be like as it is a photocopy of a photocopy... Cheers, Steve.

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