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

1936 Philco 645
#27

Let me first apologize for misstating my shadowmeter issue. The vane remains slightly deflected with MAXIMUM signal. I can bend the light bracket to center the shadow, and the shadow will narrow substantially with tuning-- it just won't be at minimum width unless the vane centers perfectly when tuned accurately.

I was going to illustrate that with photos, but unfortunately the radio went tango uniform last night (any Air Force folks out there?). No audio--no apparent signal.

Nevertheless, here's a 20-second video of the shadowmeter. Power starts when the light comes on, the vane deflects maximum left and then returns slightly towards center. The vane remains in the position it is when the video stops. This is with no shunt, no antenna, and no apparent signal. I think this is normal.

https://picasaweb.google.com/coldrb/Febr...directlink

Now, to get the radio working again. While doing nothing but turning the tuner knob, the radio went silent. Nothing but a slight hum out of the speaker. No evidence of any signal received or amplified.

I have only a rudimentary understanding of electronics, but I did my best to diagnose until 2 a.m. The only anomaly I have found is the 6A7 oscillator/detector shows zero voltage at the oscillator grid. All other tube socket and power transformer voltages are the same as before the set died

I have double-tested the 6A7 with both transconductance and emissions tester; verified the appropriate continuity through the input transformer, output transformer, oscillator transformer; and randomly tested a number of other components. As you can see, I'm now flailing aimlessly at the problem and need some direction.

So, given the sudden failure and zero oscillator grid voltage (It was -22 V), can someone give me some direction in diagnosing the problem?

I have a legible schematic posted here:

https://picasaweb.google.com/lh/photo/gv...directlink

Grateful for Guidance,
Winky


Messages In This Thread
1936 Philco 645 - by Ronin61 - 03-23-2013, 10:33 PM
RE: 1936 Philco 645 - by morzh - 03-23-2013, 11:48 PM
RE: 1936 Philco 645 - by 7estatdef - 03-24-2013, 08:58 AM
RE: 1936 Philco 645 - by Ronin61 - 03-24-2013, 11:05 AM
RE: 1936 Philco 645 - by Ronin61 - 03-24-2013, 02:21 PM
RE: 1936 Philco 645 - by Ronin61 - 03-24-2013, 02:38 PM
RE: 1936 Philco 645 - by Ronin61 - 03-24-2013, 02:39 PM
RE: 1936 Philco 645 - by Ronin61 - 03-24-2013, 02:41 PM
RE: 1936 Philco 645 - by 7estatdef - 03-24-2013, 04:06 PM
RE: 1936 Philco 645 - by Ronin61 - 03-26-2013, 04:13 PM
RE: 1936 Philco 645 - by 7estatdef - 03-27-2013, 08:38 AM
RE: 1936 Philco 645 - by morzh - 03-27-2013, 12:15 PM
RE: 1936 Philco 645 - by codefox1 - 03-28-2013, 04:34 AM
RE: 1936 Philco 645 - by Ronin61 - 04-07-2013, 09:30 PM
RE: 1936 Philco 645 - by 7estatdef - 04-10-2013, 06:27 PM
RE: 1936 Philco 645 - by Ronin61 - 04-11-2013, 04:58 PM
RE: 1936 Philco 645 - by Ronin61 - 04-22-2013, 10:57 AM
RE: 1936 Philco 645 - by 7estatdef - 04-22-2013, 05:13 PM
RE: 1936 Philco 645 - by Winky Dink - 02-02-2014, 05:57 PM
RE: 1936 Philco 645 - by Mondial - 02-02-2014, 06:15 PM
RE: 1936 Philco 645 - by Winky Dink - 02-02-2014, 06:32 PM
RE: 1936 Philco 645 - by Winky Dink - 02-02-2014, 11:20 PM
RE: 1936 Philco 645 - by Mondial - 02-03-2014, 01:07 AM
RE: 1936 Philco 645 - by Winky Dink - 02-03-2014, 03:43 AM
RE: 1936 Philco 645 - by Mondial - 02-03-2014, 09:24 AM
RE: 1936 Philco 645 - by Ron Ramirez - 02-03-2014, 11:27 AM
RE: 1936 Philco 645 - by Winky Dink - 02-03-2014, 07:35 PM
RE: 1936 Philco 645 - by Winky Dink - 02-04-2014, 01:00 AM
RE: 1936 Philco 645 - by Winky Dink - 03-24-2014, 10:10 AM
RE: 1936 Philco 645 - by codefox1 - 03-24-2014, 10:52 AM
RE: 1936 Philco 645 - by Winky Dink - 03-24-2014, 11:41 AM



Users browsing this thread: 3 Guest(s)
[-]
Recent Posts
Philco 42-1008 conversion kit
I read about a kit to convert the variable speed changer in the Philco 42-1008 into a single speed unit.  That would rem...alangard — 09:30 PM
HiFi (Chifi) tube amp build - but my own design.
Tim Well...a chassis is metal. Magnetic or not, it does not matter. A transformer has some hum to it. It is natural....morzh — 08:40 PM
Hickok AC51 tube tester
I thought the 83 tube was bad because it looked white but it tests strong. Blue gassy though. I checked the fuse, it was...martinj — 08:37 PM
Shadow Meter Bulb
Ross I am not sure what current limiting effect the incandescent provides. They are two different parts of the sch...morzh — 08:31 PM
12' Philco
Bob Thanks for that photo. I have been looking for it, and I cannot find anythinmg on the web. I forgot it was here...morzh — 08:29 PM
Shadow Meter Bulb
I think after all has been said, I will use the same bulb that is specified for the dial pilot light which is a #55. I ...georgetownjohn — 07:31 PM
12' Philco
There was also this Philco! klondike98 — 07:25 PM
HiFi (Chifi) tube amp build - but my own design.
I expected a challenge and this is just part of it. But, it's also supposed to be fun, entertaining, informative and enj...TV MAN — 07:12 PM
Shadow Meter Bulb
Butting in here with a question. Since the shadow meter is connected directly to the 1st and 2nd I.F.'s wouldn't the met...RossH — 06:43 PM
HiFi (Chifi) tube amp build - but my own design.
Mike, Tim; you are about to enter the twilight zone. Doo doo doo doo, doo doo doo doo This is something alright. I'm go...RodB — 06:26 PM

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

>