Hello, I am new to the forum but hardly new to vintage audio. I am always very appreciative of the techs that are so willing to share their experience. Together we are all more knowledgeable & stronger in general.
I was in consumer audio repair in the 70's-90's and dabbled a bit throughout the 2000's tho I can't say I'm even remotely impressed with the digital stuff from a repair perspective.
I have recently taken back up working on vintage audio as a retirement hobby. I am working on a Sansui AU-X1 that fortunately has one good power channel (for comparison) & one that the bias voltage is zero and won't adjust. The DC offset does adjust so I figure the diff amp is fine. The channel plays but as expected with low level distortion owing to no bias current. I feel fortunate that I won't have to rebuild a blown channel. This issue is the really interesting type to me.
I haven't gotten into it very far at this point & wondered if anyone has any experience with this issue. Yeah I know...hold it up to the phone & I'll see if I can tell you what is wrong (;- ). I will be providing more information as I get into it a bit further eg voltages, reference numbers, etc. I am trying to avoid taking the channel modules out as that's a lot of hard wiring disassembly & then it's usually difficult to work on in that fashion. I will when necessary but I have a suspicion the problem will be traceable while still all in the box.
I have determined that the bias diodes D04 & D03 are good. If they were open I suppose I'd have excessive bias. Thanx all, Glen Whatley
I was in consumer audio repair in the 70's-90's and dabbled a bit throughout the 2000's tho I can't say I'm even remotely impressed with the digital stuff from a repair perspective.
I have recently taken back up working on vintage audio as a retirement hobby. I am working on a Sansui AU-X1 that fortunately has one good power channel (for comparison) & one that the bias voltage is zero and won't adjust. The DC offset does adjust so I figure the diff amp is fine. The channel plays but as expected with low level distortion owing to no bias current. I feel fortunate that I won't have to rebuild a blown channel. This issue is the really interesting type to me.
I haven't gotten into it very far at this point & wondered if anyone has any experience with this issue. Yeah I know...hold it up to the phone & I'll see if I can tell you what is wrong (;- ). I will be providing more information as I get into it a bit further eg voltages, reference numbers, etc. I am trying to avoid taking the channel modules out as that's a lot of hard wiring disassembly & then it's usually difficult to work on in that fashion. I will when necessary but I have a suspicion the problem will be traceable while still all in the box.
I have determined that the bias diodes D04 & D03 are good. If they were open I suppose I'd have excessive bias. Thanx all, Glen Whatley
