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On my St-70 V2 tube plate seems to glow on one corner of vertical plate. After shut off the "burn" then looks like a water stain...if I am describing it right. i.e a small stain on the corner of the plate.
Kinda weird. My resistor is reading very much in range of 15.6 -15.8 ohms. The other is reading well within 1000 ohm range.

any thoughts

thnx

Move that tube to another position, if the same tube glows, then its the tube, if the other tube glows I would make sure your coupling capacitors are good.

Sal

I did something similar, I replaced the tube, in the same position and it showed the same plate glow. I put in new Solen's on the old original board, with the other original parts still in place.
I may be answering my own question here but could that mix / match be a problem. Should everything be replaced if you replace anything.

thanx

Mike

Can you bias the amp to 1.56 volts per channel?

The Dynaco printed circuit board was not the best quality, make sure you have no broken traces, check carefully with a magnify glass, sometimes the cracks are hard to see.

Did you replace all 6 of the larger capacitors on the board, the 4 .1uf and the 2 .05uf caps?

Also, clean the tube sockets and tighten the socket connectors with a sharp thin pin or mini screwdriver.

You can also measure the primary resistance of the output transformer, the plate to center tap (B+ connection) to plate should be close.

Let us know what the outcome is.

Sal

It holds 1.56v biased, all six capacitors were replaced [Solen], tube sockets cleaned. Still a slight glow on the plate corner. I tried a few times to upload a pic I took of it, but no luck. I am waiting for parts to replace the old board with a new one [ old layout]

Will keep checking stiuff till the board is replaced.

thnx