09-19-2020, 10:38 PM
The good news: I got the 13 tube Silvertone chassis recapped and playing.
The bad news: It has a motorboating issue related to the tone control and the flash tuning mode.
Here is a schematic (my set uses the bottom schematic, with a 6Q7 1st AF tube used instead of the 6R7 shown...Silvertone made some changes to these throughout the model year):
I've been working off of the Nostalgia Air schematic at this link on page 2 of the PDF file (again, the version on the bottom of the page, the 4588A matches mine and the yellowing paper schematic attached to the side of my chassis).
http://www.nostalgiaair.org/pagesbymodel...017127.pdf
So there seems to be some kind of a short within the tuning switch or relays, as when the BROAD/SHARP/FLASH tuning knob is turned to FLASH, it just motorboats with stations coming in faintly. In this mode, when you turn the separate tone control, lowering the tone increases the speed of the motorboating. When you turn the tuning control the opposite
direction, the motorboating slows down. Now in the BROAD or SHARP position, the radio plays fine with the tone set to more of a treble position, but when turned down to more bass (about 3/4 of the entire range), the set begins to motorboat (but not as bad as in the FLASH mode).
At one point when I went to flash mode, it killed all sound. Dead silence on all bands. And when it did come back on after turning it off for a few minutes, one of the 6N6's developed an internal short visible within the tube (a pulsating grey streak).
I haven't done a thorough voltage check yet, but voltage does seem to be a bit high. I'm getting 6.8 volts on the 6.3 main dial lamp, and at 120 VAC, the set is drawing .25 amps (which with 13 tubes doesn't seem totally out of line).
So if anyone has restored one of these high tube count 1937 Silvertone consoles with the Flash Tuning and can point me in the right direction as to what could be the culprit, I'd be most grateful. And I'm hoping Terry can give the schematic a scan and see if he can spot anything that could cause this weird issue. I traced out the tone control, the volume control, all the electrolytics and it all checks out per the schematic. Double checked the ground connections and they too seem fine.
The bad news: It has a motorboating issue related to the tone control and the flash tuning mode.
Here is a schematic (my set uses the bottom schematic, with a 6Q7 1st AF tube used instead of the 6R7 shown...Silvertone made some changes to these throughout the model year):
I've been working off of the Nostalgia Air schematic at this link on page 2 of the PDF file (again, the version on the bottom of the page, the 4588A matches mine and the yellowing paper schematic attached to the side of my chassis).
http://www.nostalgiaair.org/pagesbymodel...017127.pdf
So there seems to be some kind of a short within the tuning switch or relays, as when the BROAD/SHARP/FLASH tuning knob is turned to FLASH, it just motorboats with stations coming in faintly. In this mode, when you turn the separate tone control, lowering the tone increases the speed of the motorboating. When you turn the tuning control the opposite
direction, the motorboating slows down. Now in the BROAD or SHARP position, the radio plays fine with the tone set to more of a treble position, but when turned down to more bass (about 3/4 of the entire range), the set begins to motorboat (but not as bad as in the FLASH mode).
At one point when I went to flash mode, it killed all sound. Dead silence on all bands. And when it did come back on after turning it off for a few minutes, one of the 6N6's developed an internal short visible within the tube (a pulsating grey streak).
I haven't done a thorough voltage check yet, but voltage does seem to be a bit high. I'm getting 6.8 volts on the 6.3 main dial lamp, and at 120 VAC, the set is drawing .25 amps (which with 13 tubes doesn't seem totally out of line).
So if anyone has restored one of these high tube count 1937 Silvertone consoles with the Flash Tuning and can point me in the right direction as to what could be the culprit, I'd be most grateful. And I'm hoping Terry can give the schematic a scan and see if he can spot anything that could cause this weird issue. I traced out the tone control, the volume control, all the electrolytics and it all checks out per the schematic. Double checked the ground connections and they too seem fine.
Greg V.
West Bend, WI
Member WARCI.org
