Lifted the turret board by disconnecting all wiring from the pot side. From this angle I could see the RC206 bridge rectifier has scorched leads right where they go into the bottom of the device.
I can also see that I left a rather untidy, long lead on two of the rectifiers leads under the board.
I suspected this, but now confirmed that when I was moving the OT primary leads back-and-forth to switch positions on the output tubes, as well as moving the grid leads away from the speaker wires - all these wires are running under the turret board..
Something pushed one of these long leads into another lead on the rectifier chip, and popped it.
I disconnected all the secondaries from the PT to the board. Measure 14.75VAC of the DC heater winding, 6.9VAC off the AC heater winding, and 383VAC off the other tap. Verified with the manufacturer and these voltages are correct.
50W Build - First Startup, Bias Issue
Moderators: pompeiisneaks, Colossal
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Cathode Ray
- Posts: 203
- Joined: Sat May 26, 2018 3:22 pm
- Location: SATX
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Littlewyan
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- Location: UK
Re: 50W Build - First Startup, Bias Issue
Sounds like your PT is fine then. Should be good to just replace the rectifier and carry on.
How do you mean the lead on the rectifier was popped? Knocked loose?
How do you mean the lead on the rectifier was popped? Knocked loose?
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Cathode Ray
- Posts: 203
- Joined: Sat May 26, 2018 3:22 pm
- Location: SATX
Re: 50W Build - First Startup, Bias Issue
It smoked.Littlewyan wrote: ↑Thu Jun 16, 2022 8:56 am Sounds like your PT is fine then. Should be good to just replace the rectifier and carry on.
How do you mean the lead on the rectifier was popped? Knocked loose?
Best thing I can determine is that one of the leads off the rectifier chip contacted a metal standoff under the turret board.
PT tests good. I replaced all components in the DC heater supply.