Silvertone 1484 schematic

[shedradios]

I have the schematic from SAMS Set 700. However, it has some errors and I was wondering if there are any published revisions or service bulletins. If there aren't any known revisions I want to address a problem I'm having with the Tremolo circuit in a later thread. Thanks.
Bill

[Enzo]

Welcome to the forum. WHy not address the problem in THIS thread? Don't need lots of threads on the same amp.

Schematics often do not match amps. I don't think you will find service bulletins on it though. Old Gibson amps are notorious for this.

SHould be plenty of SIlvertone schematics over at www.schematicheaven.com You might find one closer to yours. Also, usually what you need is just the part of the schematic for the section with a problem.

[shedradios]

Thanks Enzo. Suits me I just thought a more specific subject was required. If one looks at the Silvertone 1484 schematic you see the Pin 1 plate voltage for the Tremolo 12AX7 is indicated to be 120 volts. I only get 85. This is not even within 20%. The voltage going into the neon lamp 2H is 168. The amp sounds ok, reverb and tremolo, plenty volume. So what should the pin 1 voltage read? Thanks for the help.
Bill

[Enzo]

Voltages on the prints are approximations at best. And while SAMS puts voltages all over - taken from a sample unit - I don't recall lots of voltages on the stock drawing, of course I don't remember lunch either.

If the B+ voltage is the same - is it? - but the plate is low, then the tube is conducting harder than expected. Or the plate node is being dragged down. A leaky coupling cap is often the cause fo DC on the following grid, but that leakage current can also drag down the plate it comes from. Lift the coupling cap from that plate and see if the plate voltage rises. If so, replace that cap. Have you replaced the coupling caps in there yet? Very common need in amps that age.

And if the amp sounds OK, why "fix" it?

[shedradios]

I had already replaced all caps, except couple disc ones, and out of tolerance resistors. That brought all the others in alignment with the schematic. It was really bad before I did all of that. It was time to. The plates of the 6L6's are now operating at 460 volts and that's fine. I guess the schematic is off for whatever reason. So I will leave it alone. Thanks again. You're a busy person here. Lots of good advice and knowledge being poured out on this site by you and others.
Bill