Mystery Bias voltage on Deluxe Reverb 74

Shannow985

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Yes I'll do that, keep stuff simple.
This is the PR clone I made :
20220316_170128.jpg
 

Silverface

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This is the PR clone I made :
Very neat lead dress! A couple constructive comments:

1. Please note my comment earlier about the very poor filter cap wiring - on the PR you are using the eyelets correctly. But I would suggest FILLING those. eyelets flush to the top to ensure a good connection.

2. I can't see all of the lead dress because of the angled shot, but I hope none of those nice, neat, parallel wire runs have both high voltage and signal wires close/parallel to each other. IF not - great. But if so change the layout so signal and high voltage leads run at and cross at a 90-degree angle to each other. Parallel/close signal and HV leads create a lot of noise issues.
 

Shannow985

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Thanks for the help !
I finished all the mods yesterday and wanted to keep an update.
Everything went very smoothly and everything works nicely.
First I changed the filters caps as advised (unknown age + 22uf not great with 5U4GB+dodgy solder joints):
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Here's the new job (all 16uf 475v) :
20220624_151425.jpg
 

Shannow985

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Then I tackled the transformer+bent chassis.
here's before :
20220623_221157.jpg

During :
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The micalex socket would just not fit .Correct diameter on digital caliper but obviously the hole or the socket wasn't perfcetly round. I took of 0.1/0.2mm max on the lathe.
20220623_223516.jpg
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I then didn't take pictures before final stage as I was busy and concentrated :
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The only thing I left and had to modify again was the 22k bias pot resistor. I had to go 10k ohms instead as the bias wouldn't go more than 16-18ma with 425v on plates.

The ground switch being completely useless I might use it as a bright cap switch.
 
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Silverface

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The ground switch being completely useless I might use it as a bright cap switch.
I've used them as mid boosts - same concept....take an amp "appendix" and use it for something.

I've only used standby switches when taking breaks. Which I believe was the origin of the printed term "standby", instead of "let the filaments warm up for a while - then use this thing".

Damn, I wish I had asked Leo about that!
 




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