ground loopy

[TWANG]

input jack, cliff to star grnd frnt.

R1 point.. R1 being across the input now. to star grnd. frnt.

C8 to star grnd frnt.

 

tone volume gain pots to grnd to chassis.

I took off a wired from the vol pot to star grnd frnt ..in case that was the noise producer. no difference.

 

switch to star rear

center tap R16/17 to star rear

spkr out to star rear

and the diode wire to star rear

 

 

sheilded cable off the pre amp tube.

 

non sheilded to input jack, volume pot.

 

plain wire to gain pot but the noise is there with or without the gain pot.

 

I don't see how it can be a loop producing this buzz but it sure sounds like ground noise and the

amp otherwise is just fine.

 

I did have one wire under the board somwhat close to the pwr tube so I lengthened that a bit and moved it.

 

should I move center taps from rear star to what is is. pin one? on the power tube.

I'll have to look that up I've forgotten where that runs to. supposedly to reduce noise, but kinda doubt that's my problem.

 

There is a new switch putting a cap in parallel for more voxy voice, but the noise is there with or without that switch.

also with or without the standby.

 

all the ground connects read .3 ohms max from any point, throughout the circuit.

 

heater wires are twisted.

maybe a little overlong but they run to the back and then straight over.

 

I have had enough pot swaps to know that if I had nothing but pwr vol input it would still make this same noise.

 

I am really stuck for things to do or try.

 

The only thing I see left to do is pull the board and make a whole new one.

Which even as I type it seems . . I dunno it's just frustrating.

[TWANG]

I lifted the wire off the center tap resistors and ran to cathode.

I had it this way a long time ago and changed chasing the buzz.

and it works fine now.. again.

I never ever thought that would do it but it did.

what a relief.

 

a perfectly normal vj. and a lesson learned.. apparently the buzz was somewhere else and I didnt relaize I'd gotten rid of it.

or that changing this wiring brought it back.

I dunno. something like that.

but man I feel GOOD