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

41-285 Don't Know What To Do Next
#1

Icon_sad I was told when I got this radio that a shop could not solve the problem. I did a complete chassis overhaul. All new caps, resistors, wiring etc. I've rung it out three times now and all connections are correct. I could list all voltages but they are all within spec. I've checked resistance on all IF's and they all read within tolerances. So let me just tell you what I have now.

Power up radio and there's nothing except dial lights and a soft hum from speaker. With my DMM neg. lead attached to chassis ground I can touch the positive lead to the plate of the 1st detector XXL tube and music comes out of the speaker. I am tuned to 1260 on the dial. Strongest local station. Moving the tuning capacitor changes nothing. I still hear the same station. Only difference is that the speaker seems to sound like a sweep oscillator but the station still comes in. I did an oscillator check with a known good radio tuned to 1255Khz and the 41-285 tuned to 800Khz and the oscillator is working. The volume control works when listening to this station as well as the tone pot. I disconnected one end of the .01ufd cap (#38 on schematic). I connected a test lead to the plate of one of the 41 output tubes and the other end of that lead to a .001ufd cap. A lead to the other side of the .001ufd cap I connected to the high side of the volume pot where the #38 was disconnected. I powered up the set and slowly cranked up the volume. This produced a noise from the speaker that also sounded like a sweep oscillator so I'm confident my audio circuit is good.

So this is where I'm at. I do not know how to induce a signal into the individual stages to check the IF circuits. Would this be the next step? I have a frequency generator that does give me a solid 455Khz signal if necessary. I sure could use some help with this one folks.

Thanks much,
Johnny


Messages In This Thread
41-285 Don't Know What To Do Next - by Johnny - 04-16-2009, 11:07 PM
Re: 41-285 Don't Know What To Do Next - by Johnny - 04-17-2009, 12:27 AM
Re: 41-285 Don't Know What To Do Next - by Johnny - 04-17-2009, 02:47 AM
Re: 41-285 Don't Know What To Do Next - by Johnny - 04-17-2009, 04:41 PM
Re: 41-285 Don't Know What To Do Next - by Johnny - 04-17-2009, 07:09 PM
Re: 41-285 Don't Know What To Do Next - by Johnny - 04-17-2009, 10:21 PM
Re: 41-285 Don't Know What To Do Next - by Johnny - 04-19-2009, 08:56 PM
Re: 41-285 Don't Know What To Do Next - by Johnny - 04-20-2009, 11:54 AM
Re: 41-285 Don't Know What To Do Next - by Johnny - 04-20-2009, 03:35 PM
Re: 41-285 Don't Know What To Do Next - by Johnny - 04-20-2009, 07:45 PM
Re: 41-285 Don't Know What To Do Next - by Johnny - 04-21-2009, 02:20 PM



Users browsing this thread:
[-]
Recent Posts
PT 6 chassis screws size???
Hello bridKarl, that sounds right or maybe 8/32 . Sincerely Richardradiorich — 01:00 AM
PT 6 chassis screws size???
Have this done except for missing chassis screws. It looks like 1 inch 6/32 sheet metal screw may work but can anyone s...bridkarl — 10:32 PM
Philco model 38 code 121 not receiving signal.
Hello Stormlord, Well done on rewinding that coil it turned fairly good for your first one. Sincerely Richardradiorich — 09:12 PM
Philco model 38 code 121 not receiving signal.
Well here it is. It ain't pretty, but hopefully it'll work. I checked it with my DMM on continuity and it keeps and r...Stormlord5500 — 08:56 PM
Philco 42-345 Restoration/Repair
Yes, 57 is an electrolytic cap that should be 12 mfd 400 volts according to the parts list from the Phorum library schem...RodB — 06:01 PM
Philco 42-345 Restoration/Repair
Looks like if I am reading it correctly it looks like the silver capacitor#57 that appears to be a replacement is of a l...osanders0311 — 05:09 PM
Philco model 38 code 121 not receiving signal.
Thanks Arran. Yeah this plastic is pretty thin. It's a little thinner than the original stuff. It kinda reminds me of p...Stormlord5500 — 04:37 PM
Testing a speaker and output transformer Trutone A2-G
The equivalent of one short turn is basically the same as that of a shorted load. If it is the primary's turn, then the ...morzh — 03:53 PM
Testing a speaker and output transformer Trutone A2-G
I've never had an output transformer become shorted, the failure mode is usually an open primary, or in a center tapped ...Arran — 03:52 PM
Philco model 38 code 121 not receiving signal.
As long as the plastic sheeting isn't too thick, I think that the thickness of photographic film would be just about rig...Arran — 03:19 PM

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

>