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Bias adjustment for the CARY SLI-80 Integrated Amp

To my fellow tube lovers: I have been here before, and I am back because I need help in solving an issue I have been having with my Cary SLI-80 Integrated Amp.
Very Simple: I cannot adjust the bias reading on the LEFT channel. After warm-up [about 10-15 minutes] I can set/reset the bias reading to 75-80 ma. Wait... there is more .... After about 30 minutes, with or without music, with the meter connected, one sees all of a sudden the needle jumping all over the place; talk about erratic readings: as low as 30 ma and then as high as 150 ma. When I try to adjust down the potentiometer, it gets to a point counterclockwise, where I can no longer adjust it, and it still reads a very erratic reading. If I adjust clockwise, the mamps start to go up even higher.
Either the outer-most power tube on the left gets RED HOT, or the power fuse blows. If I reverse the tubes [right to left and so on, one would think that the issue would be reversed, but it is NOT. Same erratic reading on the outer-most LEFT SIDE. SOMETHING IS WRONG IN THE WIRING INSIDE THE AMP. The problem is that the amp has been doing this now for quite some time and it has been sent back to Cary where they charge and tell me that nothing is wrong.

Where do I need help? Does one of you kind folk have a SCHEMATIC of the SLI-80 that I can get from you to see if I can track where the damage is? Or perhaps you’ve had a similar experience and knows where trhe problem lies. I really need help on this. Best to all and stay well during these trying times. Richard
richfrank

Showing 3 responses by richfrank

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richfrank OP
34 posts
 
Hello oldhvymec:   I reversed all the tubes; that is the left side tubes went into the right side, and viceversa. If it would be a tube, and only a tube, one would assume that the bias readings would be reversed, and that is not the case. After switching tubes, the left channet bias was still swinging wildly from 20 ma up to around 150 ma.  Sounds like a fliter ? or resister? giving me issues. My problem? I don't know which is the culprit.
Regards,
richfrank's avatar
richfrank OP
34 posts
 
To Jond: I don't live in the US, and the cost of shipping a 50 LB carton is very expensive. Second; I have sent it back to Cary around May 2020 and they claim they fixed it, and reset the bias,  and the bias issue was "all my fault". It worked for a couple of months.    What can I say .....

To oldhvymec: I believe you missed several points brought up by me:
1- The SLI-80 is an integrated amp with both Left and Right channels. 
2- The Digital Multimetr is not an issue because I can read BOTH sides independently, and when plugged into the right side, the meter is steady right at 75 ma (and the potentiometer reacts to my turning it CW or CCW).
It is the left side that the meter swings erratically. Logic would dictate that if the DMM were damaged, I would see similar irregularities on both chanels; that is not the case.  Only the left side does NOT hold the correct bias!
3- The SLI-80 does not have a "standby" switch.

Your second commentary seems to be more accurate. It could be a resistor. That is why I am asking if someone can obtain a SCHEMATIC for an SLI-80 Amp.

Please help me out here!
Regards ....
richfrank's avatar
richfrank OP
34 posts
 
Great advise. Sounds simple enough. I do appreciate your wise comments about putting one hand in a pocket and discharging all caps. I will follow suit and give you an update after this weekend.
Be well and stay well during these difficult times.
Regards....
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