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hugeshows hugeshows is offline
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Default Restoring a Sherwood S-5000

Hi There,

So my memory must be failing me in my old age. First off, I've been saying this whole thread that the max capacitance of a 5AR4 is 20uf. Well, I knew better at one point and I am embarrassed to say that I've looked it up and it's 60uf. So, you could put more capacitance at the rectifier, but the result would be raised voltages. I can see that your cap has been replaced.. Can you check and see what the capacitance off that first section is? If not, please measure the AC output of the transformer secondary (the HV feeding the rectifier) and post your findings. It also seems that the big main cap has two sections tied together. Knowing all those values would be useful.

Your line voltage is right where mine is at. Unless we see a difference in the voltage coming off the power transformer, the elevated voltages are probably a result of the work that's been done. I really wonder what that section of the cap is coming off the rectifier.

On the other hand, if those output tubes can handle the voltage and it sounds good, we might want to go with it. The preamp tubes are not getting that much more voltage than they're used to, they're not cooking. Those Russian military versions of the EL84 you have are rated for 500v on the plates, so you're OK there. You'll be forced to keep looking for HV tubes but that thing is probably making 26-27W at those voltages! Have you measured the plate current draw yet? What's the BIAS voltage running at?

So, here's what I need to help:

AC voltage on HV secondary of power trans (loaded)
Capacitance of that first section
Bias voltage and plate current measurements

While those repairs seem a bit klunky, they might be OK. I'm a little worried about whatever splice that is shrinkwrapped near the transformer, though It might just be a ground wire.

We'll get back to the phono section soon, let's check and make sure everything else is ok first.

Cheers,

-forkinthesocket