Strange sound - Sansui AU317

stians

New Member
Hello

I have a recapped Sansui AU317, and it sounds really good. When not in use (but powered on), it suddenly "pops" and a high pitched sound appears decreasing down to a lower tone (I can hear the pulse (40-50hz maybe)), then disappearing. It takes 2-3 secinds. It works well before and after and I have never experienced it during use. I believe it's only in the right channel, but not sure.
Anyone familiar with this problem?

Regards
Stian, Oslo
 
It is probably a noisy transistor. Next time it does this, turn the volume down and see if it affects it. If the sound stops when you turn the volume down, the problem is in the power amp. If not, it's in the preamp.
 
Thanks guys, I'll try being quick next time it happens :)
Could it be a problem in the phono-stage? I don't remember whether it only appears on phono or all. Will check it out tonight.

Regards/ Stian
 
From previous experience any of the transistors in the 'Control Amp' could cause this issue, for the right channel this will be TR2,4,6,8. Or the dual diodes (VD1212) found in both the Control Amp and the Phono (Head) Amp can be troublesome.
 
From previous experience any of the transistors in the 'Control Amp' could cause this issue, for the right channel this will be TR2,4,6,8. Or the dual diodes (VD1212) found in both the Control Amp and the Phono (Head) Amp can be troublesome.

Thanks a lot. Are these transistors/diodes still possible to obtain?

Regards /Stian
 
Are these transistors/diodes still possible to obtain?
The original type numbers have very likely not been made for decades, but there are modern substitutes which work as well, or better, than the originals.

Today for example, we would replace the VD1212 dual diodes with 2 x 1N4148 diodes connected in series. For TR02, TR04 & TR06 we would use KSA992 and for TR08 we would use KSC1845, there are others but these type numbers are the most commonly used replacements. Elsewhere on AK there is a thread devoted entirely to old type number semiconductors and their modern readily available replacements. ;)

Do some searching and reading around AK, there is much information about the AU-317 including threads describing how to recondition them in some detail.
 
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It is probably a noisy transistor. Next time it does this, turn the volume down and see if it affects it. If the sound stops when you turn the volume down, the problem is in the power amp. If not, it's in the preamp.
Sorry, I meant to say that if the sound goes away when you turn the volume down, the problem is in the preamp.
 
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