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Cayin A50t biasing problem

I recently purchased this amp on a'gon and having trouble getting it bias. When try to measure the bias I get no reading on any of the pots. When I try to raise the bias, the travel of the pot is very small like 3/4 of a turn. Is this normal. I have had many tube amps so I think I understand the process. I can't believe I have 4 bad pots nor 4 bad tubes. What give anyone?
128x128larryrx7
newbee
4,751 posts
 
The pot travel of 3/4ths of a turn is not unusual. Three of my amps do this, including a Cayin. The bias curcuit not functioning at all is a different matter. I don't own a A50t so I don't know but is it possible the bias circuit is seperately fused and a fuse has blown? Is it possible that the previous owner blew out a resistor(s) in the bias circuit that might affect all of the pots? You might take off the lid and see what is there. After its fully discharged of course.
williamredburry
51 posts
 
I own a A55T. When I bought it i was told to use sharp ( pointed) electrodes to do the measuring. If it has a blunt tip it won't measure anything. Maybe this helps. Good luck.
larryrx7's avatar
larryrx7 OP
137 posts
 
To answer Williamredburry idea...I do have a very small reading of about 15-20 MW so I think I have a circuit connection...Newbee, you might have something but since I have a low reading, I think it may be a faulty bias circuit but it is kind of odd it would be in all the pots. I had one once that had 1 bad one. What do you think?
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