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Sorta newbie 38-690 low volume
#14

So here's what I found:
  • 6L6 voltages on pins 3, 4, and 5 are 324, 324, and -26 for both tubes.
  • Tweeter FC volts are 332 and 254 (78v drop) for the "warm" FC that feeds the output amp.
  • The other tweeter FC is 292 and 250 (42v drop) for the "cool" FC that feeds the tuner.
  • The #83 front treble pot (nearest the shaft) goes to 6N7 2nd audio tube.  Schematic says 1M ohm.  It measures 1.4M ohm.  At the center terminal it's 1K ohm CW and .72M ohm CCW.
  • The #67 rear pot goes to the 1st IF 6K7 tube.  Schematic says 2800 ohm.  It measures 435 ohm.  Center terminal goes up to 900 ohm, then drops to 600 ohm full CW.  It's 29 ohm CCW. 
So the output amp looks good, but the treble pots look suspicious.  I'm wondering if it could also be causing the lower FC voltage on the one tweeter that feeds the tuner.


Messages In This Thread
Sorta newbie 38-690 low volume - by Hot Rod - 11-29-2017, 08:35 PM
RE: Sorta newbie 38-690 low volume - by morzh - 11-29-2017, 11:22 PM
RE: Sorta newbie 38-690 low volume - by Hot Rod - 11-30-2017, 12:46 PM
RE: Sorta newbie 38-690 low volume - by morzh - 11-30-2017, 01:08 PM
RE: Sorta newbie 38-690 low volume - by Hot Rod - 11-30-2017, 06:45 PM
RE: Sorta newbie 38-690 low volume - by morzh - 11-30-2017, 11:15 PM
RE: Sorta newbie 38-690 low volume - by morzh - 12-01-2017, 11:13 AM
RE: Sorta newbie 38-690 low volume - by Hot Rod - 12-01-2017, 12:08 PM
RE: Sorta newbie 38-690 low volume - by morzh - 12-01-2017, 03:36 PM
RE: Sorta newbie 38-690 low volume - by Hot Rod - 12-03-2017, 04:50 PM
RE: Sorta newbie 38-690 low volume - by morzh - 12-03-2017, 06:20 PM
RE: Sorta newbie 38-690 low volume - by Hot Rod - 12-03-2017, 06:37 PM
RE: Sorta newbie 38-690 low volume - by morzh - 12-03-2017, 10:24 PM
RE: Sorta newbie 38-690 low volume - by morzh - 12-05-2017, 08:33 AM
RE: Sorta newbie 38-690 low volume - by Hot Rod - 12-05-2017, 06:44 PM
RE: Sorta newbie 38-690 low volume - by Hot Rod - 12-05-2017, 06:46 PM
RE: Sorta newbie 38-690 low volume - by Hot Rod - 12-05-2017, 08:28 PM
RE: Sorta newbie 38-690 low volume - by morzh - 12-05-2017, 11:03 PM
RE: Sorta newbie 38-690 low volume - by Hot Rod - 12-06-2017, 12:45 PM
RE: Sorta newbie 38-690 low volume - by morzh - 12-06-2017, 01:26 PM
RE: Sorta newbie 38-690 low volume - by Hot Rod - 12-07-2017, 07:37 PM
RE: Sorta newbie 38-690 low volume - by morzh - 12-07-2017, 07:46 PM
RE: Sorta newbie 38-690 low volume - by Hot Rod - 12-07-2017, 08:47 PM
RE: Sorta newbie 38-690 low volume - by morzh - 12-07-2017, 10:57 PM
RE: Sorta newbie 38-690 low volume - by Hot Rod - 12-08-2017, 12:19 PM
RE: Sorta newbie 38-690 low volume - by morzh - 12-08-2017, 01:39 PM
RE: Sorta newbie 38-690 low volume - by Hot Rod - 12-08-2017, 11:21 PM
RE: Sorta newbie 38-690 low volume - by morzh - 12-09-2017, 10:26 AM
RE: Sorta newbie 38-690 low volume - by Hot Rod - 12-09-2017, 01:39 PM
RE: Sorta newbie 38-690 low volume - by morzh - 12-09-2017, 03:01 PM
RE: Sorta newbie 38-690 low volume - by Hot Rod - 12-09-2017, 07:04 PM
RE: Sorta newbie 38-690 low volume - by morzh - 12-09-2017, 08:37 PM
RE: Sorta newbie 38-690 low volume - by Hot Rod - 12-10-2017, 07:01 PM
RE: Sorta newbie 38-690 low volume - by morzh - 12-10-2017, 07:23 PM



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