Welcome Guest! Be sure you know and follow the Phorum Rules before posting. Thank you and Enjoy! (January 12, 2025) x

Thread Closed

grid voltages
#1

Any one with an idea as to what g1 volts shoud be for a 650. I have distorted audio (clipped) and suspect the 78 tube is bad but G1 voltages would be a help for the whole set as well.

Dave Casazza
Keep em glowin and goin...
#2

The reason G1 voltages aren't typically shown is that they will measure differently with different types of meters because of the loading effects.

One approach is to simply use the specs from a tube manual (or online tube data source) http://tdsl.duncanamps.com/ and you MUST use a meter with a high input resistance. Modern Digital meters or VTVMs generally fit the bill and they didn't have them back in those days.

Where there is a cathode resistor involved the cathode voltage will often tell the story but that requires that the tube be in good shape.

Could you describe your distortion a bit more? Normally neither of the 78s would account for that. Have you recapped the set ?




Users browsing this thread: 1 Guest(s)
[-]
Recent Posts
54C Complete Teardown/Rebuild
Hello Roy, here is this one sincerely Richardradiorich — 12:45 AM
54C Complete Teardown/Rebuild
Richard, Had grabbed it already but thank you just the same.  I find myself wanting to find some way to block out the...glyphmon — 12:03 AM
54C Complete Teardown/Rebuild
Hello roy, here is a link to the schematic . Sincerely Richardradiorich — 11:54 PM
54C Complete Teardown/Rebuild
Richard, The Silvertone 2014 also is a transformerless set, so I am incorporating a 1:1 600 ohm audio isolation transfo...glyphmon — 11:37 PM
Preliminary work on wife's Silvertone 2014
Did an alignment today which was interesting.  IF alignment went great, almost all was already spot-on.  Adjusting on th...glyphmon — 11:35 PM
54C Complete Teardown/Rebuild
The main problem with adding a Bluetooth input is that this set lacks a traditional power transformer to isolate it from...radiorich — 11:19 PM
54C Cabinet Refinish
I started stripping this cabinet before it got super chilly out because I knew I wasn't going to be able to work on ...glyphmon — 11:18 PM
54C Complete Teardown/Rebuild
While I'm waiting to wrap up the final steps on my wife's Silvertone 2014, I started disassembly on the next project.  O...glyphmon — 11:07 PM
Preliminary work on wife's Silvertone 2014
Hello roy, that great news glad it worked out for you !! Sincerely Richardradiorich — 10:50 PM
Preliminary work on wife's Silvertone 2014
Safety caps arrived today.  Soldered one in and had a successful first power-up.  No magic smoke escaped and it tunes in...glyphmon — 09:53 PM

[-]
Who's Online
There are currently no members online.

>