Champ pulsing DC

Fender Amp Discussion

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goldenGeek
Posts: 170
Joined: Fri Nov 16, 2012 12:40 pm

Re: Champ pulsing DC

Post by goldenGeek »

martin manning wrote:I agree make sure that the master pot is grounded. Does this problem occur when that pot is turned down (~12 o'clock)? If not that confirms that 1M to ground is too much. I would make that pot a 250k at most. You can try putting a 220k-270k across the outer lugs to test that theory.
I actually removed the master volume :oops: to keep things simple when searching for the problem(s). There was some other issues initially but I guess I should have put the master back in. You're referring to the master and not the volume/gain, right? You're absolutely right that this only occurs at volumes over some place between 12 and 2'o clock. I'll give it a go with a 250k pot... I really belive that this will get this amp going. Theres quite a bit of lead dress to address but now I'm confident that it'll work out fine. Thank you all for your time :) And I will post back, hopefully with good news .
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didit
Posts: 1115
Joined: Thu Sep 25, 2008 3:37 pm
Location: Canada

Re: Champ pulsing DC

Post by didit »

goldenGeek wrote: I actually removed the master volume [...]
You did put a fixed ~200K resistor in replacing it?
goldenGeek
Posts: 170
Joined: Fri Nov 16, 2012 12:40 pm

Re: Champ pulsing DC

Post by goldenGeek »

didit wrote:
goldenGeek wrote: I actually removed the master volume [...]
You did put a fixed ~200K resistor in replacing it?
:oops: :oops: ...no I forgot. Tried to add a 220k on the master pot and wired it back in - everything seems to be working fine now. I'll have to wire the other 6v6 back in, but things seems to work out okay :D

A big thank you to everyone who helped out :D
goldenGeek
Posts: 170
Joined: Fri Nov 16, 2012 12:40 pm

Re: Champ pulsing DC

Post by goldenGeek »

Everything is good now, but I have some questions regarding lead dress/wiring. Theres a hum going on that gets a little bit quieter when the master is fully on. Is that a common problem?

Also, does the wiring in the attached picture look okay, or is it a bad thing runnig the heater wires over the power tubes? I know its a good thing to keep is as short as possible, but theres a lot of wires going parallel here because of the dual 6v6s.

Edit: and, I was out of 470R resistors so I added 820R stoppers on pin 4 - is that okay, or too much? I run 1.5k on pin 5, I guess thats a "normal" fender-ish value.
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