04-03-2017, 08:51 PM
Working on what I thought would be a fairly simple one band, 5 tube radio. It's been not so simple so far...
After checking all the tubes, doing a complete recap, and changing the resistors that were way out of tolerance, I'm left with a radio with very low volume with the pot wide open. I even replaced the volume control with a new 500K as per the schematic to no avail. My voltages are rather LOW (unfortunately the schematic doesn't list many voltages other than for plates) and I'm wondering if someone here could take a look at the numbers and perhaps point me towards what the culprit of the low volume may be? I'm working off of the 37-93 schematic, which most all sources online seem to indicate is the same as the 38-93. Just to be sure I'm ordering a set of 38-93's from Chuck. When I touch the grid caps of the tubes with the soldering iron I get a low buzz. It should be a whole lot louder. Ditto for the center tap of the volume control...very low volume buzz. The audio output transformer checks out at 455 ohms. I'm only getting 2 ohms on the 6R7 however (well, 2.2) but it should be 25 volts.
After checking all the tubes, doing a complete recap, and changing the resistors that were way out of tolerance, I'm left with a radio with very low volume with the pot wide open. I even replaced the volume control with a new 500K as per the schematic to no avail. My voltages are rather LOW (unfortunately the schematic doesn't list many voltages other than for plates) and I'm wondering if someone here could take a look at the numbers and perhaps point me towards what the culprit of the low volume may be? I'm working off of the 37-93 schematic, which most all sources online seem to indicate is the same as the 38-93. Just to be sure I'm ordering a set of 38-93's from Chuck. When I touch the grid caps of the tubes with the soldering iron I get a low buzz. It should be a whole lot louder. Ditto for the center tap of the volume control...very low volume buzz. The audio output transformer checks out at 455 ohms. I'm only getting 2 ohms on the 6R7 however (well, 2.2) but it should be 25 volts.
Greg V.
West Bend, WI
Member WARCI.org
