Help- Studio Preamp suddenly not working... suspicious wire...

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erickompositör72

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I hadn't used the StudPre in a couple of days (IIC+ arrived! 8) ), so I was puzzled when I was plugging it in, and it was needing the master to be pushed past 3-4 on the Mark II power amp, only to hair a faint, fizzy sound.

I opened it up, and here's what I found -

(I think the reverb is messed up, too? It was like this when I received it in the mail a couple of months ago- I never use reverb so I didn't care...)

20200716_143519.jpg


and this suspicious wire just lying here:

20200716_143531.jpg


It looks to be disconnected from something. I have no idea how or when it happened, but I guess it could have happened in the last couple of days?
 
That white wire needs to be connected to the reverb tank. Locate the tab, just below the green wire (in the photo) that has a bit of solder already.

As to the low output/fizzy sound... start with the obvious stuff like swapping tubes (V4 drives the Main outs), trying the FX loop send (also, be sure to check the Line/Low switch). It could be anything, but narrow down the obvious stuff first.
 
dtrax said:
That white wire needs to be connected to the reverb tank. Locate the tab, just below the green wire (in the photo) that has a bit of solder already.

As to the low output/fizzy sound... start with the obvious stuff like swapping tubes (V4 drives the Main outs), trying the FX loop send (also, be sure to check the Line/Low switch). It could be anything, but narrow down the obvious stuff first.

Thanks- I switched all the tubes, tried a different amp's loop return for the power section, tried all the outputs- they all behave the same way. I guess I'll just take it to a Mesa service center.
 
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