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Sansui A-60 question

My understanding of the "history" of the A-60 DC Servo amp is that the quality of the circuits is actually quite good...it just happended to be manufactured at the "begining of the end" for Sansui and the chasis/knobs were cheapened but the GUTS were still the standard Sansui quality...my experience has been fantastic with this amp powering Infinity Reference 5 speakers that are perfectly matched (8ohm) and a really nice NAD CD player: the sound is awsome Sansui all the way and i get NO distortion. I learned to REALLY clean the pots/switches and remove any noise from the path. In my opinion the sound quality is absolutely clean!
 

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the amp sounds more than okay to my ears, sometimes i like to listen to this amp on headphones besides Pioneer VSX9900S and Pioneer DS1.
 
RS-MN said:
I just fixed my A-60. I bought it at a garage sale with a Sharp Tuner ($100 for all). They said everything worked, but there was no way to test it, so I took a chance. The left channel worked but the right had distortion that increased with the volume. I looked at the internals and someone had put different transistors on one channel. I changed out both sets of transistors and replaced the largest 3 capacitors. It sounds beautiful now. The photo of the transistors is how it was when it wasn't working well. The 2 transistors on the right were originals, the ones on the left were something different. I found some info online that recommended these transistors as replacements - 2SC5200-O and 2SA1943-O. $43 for parts/shipping and it's all good now. I also replaced the light bulb with an LED (a pre-assembled 5V-12V with a resistor in line.)
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I also have an A-60 but it has a terrible balance issue. When the balance pot is at 12 o'clock the right channel is only 50% of the left. All the transistors check fine and it has had a FULL recap. When checking the volume pot with a meter it checks perfect 250k ohm and 122 side to side. Have tried it with several speakers and cables with the same result. Other than balance issue it works great and I can listen to it with the balance in the 3 o'clock position. Is it possible the HFE on the input transistors is way off left to right. Any ideas?
 
taineasy said:
I also have an A-60 but it has a terrible balance issue. When the balance pot is at 12 o'clock the right channel is only 50% of the left. All the transistors check fine and it has had a FULL recap. When checking the volume pot with a meter it checks perfect 250k ohm and 122 side to side. Have tried it with several speakers and cables with the same result. Other than balance issue it works great and I can listen to it with the balance in the 3 o'clock position. Is it possible the HFE on the input transistors is way off left to right. Any ideas?
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This was probably done, but I would double check the bias current values and adjust as needed. I'm not sure what would need to be done if that doesn't fix it.
 
taineasy said:
I also have an A-60 but it has a terrible balance issue. When the balance pot is at 12 o'clock the right channel is only 50% of the left. All the transistors check fine and it has had a FULL recap. When checking the volume pot with a meter it checks perfect 250k ohm and 122 side to side. Have tried it with several speakers and cables with the same result. Other than balance issue it works great and I can listen to it with the balance in the 3 o'clock position. Is it possible the HFE on the input transistors is way off left to right. Any ideas?
Click to expand...
I'd start a new thread explaining your problem, it will get better response and attention than a 13 years old thread with 3 pages of information not related to your problem.
 
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