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VTA Upgrade to Dynaco ST-70 problem.

Well i think I may have found the problem. The LM334 for the right channel gave up the ghost tonight. Btw the voltages coming out of the rectifier is 465vdc at the B+ input to the board is 407vdc when the line voltage is 120vac. I have 2 new lm334s on the way. I had ask Roy if he thought that was the source of my problem but the voltages were so close he didn't think so. I noticed when checking R19 and R20 they were way different and then the right channel just died. :-(

Thanks again for everyones comments and guidance. I will see what happens after the replacement.
 
I would change out that 5 watt wire wound resistor at the quad cap lug 3-4 to a carbon comp 3 watt.
The important thing here is that you want around 380vdc on the driver board, and usually 2.2K is about the right amount to get that.
Try it first, then adjust if necessary. You will need to have all tubes installed and biased before making the voltage check.
 
Well I just wanted to thank all of you for your input and guidance. The LM334 was bad and the new one fixed the problem. I did put the original 2.2k resistor back in between the 3rd and 4th lugs of the can cap and the amp sounds amazing like it should of from the get go. I do like the Mundof caps but I have several others I plan on trying out over time. Thanks again guys!
 
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