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

Thread Closed
Thread Rating:
  • 0 Vote(s) - 0 Average
  • 1
  • 2
  • 3
  • 4
  • 5

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, 09:35 PM
RE: Sorta newbie 38-690 low volume - by morzh - 11-30-2017, 12:22 AM
RE: Sorta newbie 38-690 low volume - by Hot Rod - 11-30-2017, 01:46 PM
RE: Sorta newbie 38-690 low volume - by morzh - 11-30-2017, 02:08 PM
RE: Sorta newbie 38-690 low volume - by Hot Rod - 11-30-2017, 07:45 PM
RE: Sorta newbie 38-690 low volume - by morzh - 12-01-2017, 12:15 AM
RE: Sorta newbie 38-690 low volume - by morzh - 12-01-2017, 12:13 PM
RE: Sorta newbie 38-690 low volume - by Hot Rod - 12-01-2017, 01:08 PM
RE: Sorta newbie 38-690 low volume - by morzh - 12-01-2017, 04:36 PM
RE: Sorta newbie 38-690 low volume - by Hot Rod - 12-03-2017, 05:50 PM
RE: Sorta newbie 38-690 low volume - by morzh - 12-03-2017, 07:20 PM
RE: Sorta newbie 38-690 low volume - by Hot Rod - 12-03-2017, 07:37 PM
RE: Sorta newbie 38-690 low volume - by morzh - 12-03-2017, 11:24 PM
RE: Sorta newbie 38-690 low volume - by morzh - 12-05-2017, 09:33 AM
RE: Sorta newbie 38-690 low volume - by Hot Rod - 12-05-2017, 07:44 PM
RE: Sorta newbie 38-690 low volume - by Hot Rod - 12-05-2017, 07:46 PM
RE: Sorta newbie 38-690 low volume - by Hot Rod - 12-05-2017, 09:28 PM
RE: Sorta newbie 38-690 low volume - by morzh - 12-06-2017, 12:03 AM
RE: Sorta newbie 38-690 low volume - by Hot Rod - 12-06-2017, 01:45 PM
RE: Sorta newbie 38-690 low volume - by morzh - 12-06-2017, 02:26 PM
RE: Sorta newbie 38-690 low volume - by Hot Rod - 12-07-2017, 08:37 PM
RE: Sorta newbie 38-690 low volume - by morzh - 12-07-2017, 08:46 PM
RE: Sorta newbie 38-690 low volume - by Hot Rod - 12-07-2017, 09:47 PM
RE: Sorta newbie 38-690 low volume - by morzh - 12-07-2017, 11:57 PM
RE: Sorta newbie 38-690 low volume - by Hot Rod - 12-08-2017, 01:19 PM
RE: Sorta newbie 38-690 low volume - by morzh - 12-08-2017, 02:39 PM
RE: Sorta newbie 38-690 low volume - by Hot Rod - 12-09-2017, 12:21 AM
RE: Sorta newbie 38-690 low volume - by morzh - 12-09-2017, 11:26 AM
RE: Sorta newbie 38-690 low volume - by Hot Rod - 12-09-2017, 02:39 PM
RE: Sorta newbie 38-690 low volume - by morzh - 12-09-2017, 04:01 PM
RE: Sorta newbie 38-690 low volume - by Hot Rod - 12-09-2017, 08:04 PM
RE: Sorta newbie 38-690 low volume - by morzh - 12-09-2017, 09:37 PM
RE: Sorta newbie 38-690 low volume - by Hot Rod - 12-10-2017, 08:01 PM
RE: Sorta newbie 38-690 low volume - by morzh - 12-10-2017, 08:23 PM



Users browsing this thread: 1 Guest(s)
[-]
Recent Posts
The list of my radio & TV collection!
Yes, Michael. But strangely enough, I managed to keep the original veneer. I must admit that I don't really like it, so ...RadioSvit — 02:21 PM
The list of my radio & TV collection!
Good radio. I bet there was a lot of veneer fixing.morzh — 02:16 PM
Philco 46-480 Electronic Restoration
>> it is because I am retired and a little demented. You have just the right amount of it. No perfectly sane p...morzh — 02:14 PM
The list of my radio & TV collection!
Old Zenith 5S-29 tube radio. First turn-on after repair and reception quality testing. Demonstration of the operation of...RadioSvit — 01:27 PM
Philco 42-345 Restoration/Repair
Welcome to the Phorum, osanders0311!  Regardless how far you intend to restore this set, first priority should be replac...GarySP — 11:51 AM
Philco 46-480 Electronic Restoration
Joseph, it is because I am retired and a little demented. My problem is that I wanted to own a collection that spans th...MrFixr55 — 11:29 AM
Philco 46-480 Electronic Restoration
Wow, here I am with only two restored radios. I’ve got to boost those numbers! If you can’t run with the big dogs, you m...jrblasde — 10:04 AM
Philco 46-480 Electronic Restoration
Hello MrFixr55, That will for sure keep you out of trouble! Last Sunday was spent mostly doing yard work anyway the we...radiorich — 09:50 AM
Philco 46-480 Electronic Restoration
Throw in all the Audio equipment that has to be kept in a bedroom (my office)L. 8 portable self contained PA speakers, ...MrFixr55 — 07:40 AM
Philco 42-345 Restoration/Repair
Looking at the pic supplied by Rod B, you can duplicate the missing loop antenna. 10 gauge copper wire can be used to m...MrFixr55 — 01:20 AM

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

>