Sansui AU 20000 intermittent protection mode.

[clovis]

Please help. My Sansui AU 20000 goes protection mode intermittent. After approximately 1 hour of play, it goes protection mode. I shut it down. then I continue to play then it goes protection mode. Sometimes cold start, it goes protection mode. I had it checked, after 2 technicians, it is the same thing. Right anf left channels are ok, the same volumes. I clean the potentiometers and the speaker output and the rca inputs using Deoxit D5. It really plays welll when not in protection mode.

I appreciate any help. Thanks in advance.

 

[richardpp]

Hi Clovis, welcome to Audio Karma!

As far as my understanding goes, as long as basic checks for DC offset and correct bias have been carried out, problems with the amp in protection mode can be caused by faulty transistors on the driver circuit board and/ or bad solder joints within the main heatsink assemblies. The intermittent nature of the problem might suggest the latter. There was a recent example here on the forum where a bad solder connection to the thermistor which senses temperature of the heatsinks caused the amp to go into protection mode.
However these are specific incidents and as such the overall response here might be be to find someone with the time, patience and expertise to go through the amp. It is a great amp and well worth getting looked at if you can find someone that knows sansui.
Where abouts are you located and can you let us know the serial number of your amp?

Cheers,
Richard

 

[clovis]

Hi Richard, thank you for your prompt reply. I bought the Sansui AU 20000 off ebay years ago. The seller had a demo I saw in Youtube, When it arrived. I tested it and it worked then half an hour later it went on protection mode. It is quite heavy to return so I took it to a local shop in Montreal Radio St Hubert. Now I can play it but now over an hour it goes protection mode so I am not inclined to take it there again as the job I feel is not thorough for a reputable shop. I would shut it down and restart. There are times cold start and protetion mode right away. I used Deoxit D5 to clean all the potentiometers, knobs already. I would wait a day then it plays then protection mode. S/N 236080126. It came from the states. Someone might recognise who had serviced it in the states. Do you know an expert here in Montreal, Quebec?

Thanks,
Clovis

 

[richardpp]

Thanks for the information, unfortunately I don't know of anyone in the Montreal area. Perhaps there's someone else on the forum who knows of a good repair shop in the area or recognises the symptoms you're describing and can help.