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

Philco 640 - Need Some Help
#8

(06-30-2016, 10:06 AM)Steve Davis Wrote:  The very first thing to do is, touch the grid cap of the 85 tube with your finger. Do you get a loud hum? Next, place another radio next to the radio under test to see if you can tune the local oscillator of the nonworking radio.

Steve

This is the strategy that should be used with any dead radio - (1) Can you get some hum in the speaker by touching the grid of the last couple stages? Then your audio section is probably working.  Otherwise, concentrate on those last one or two stages.

If the audio is working, (2) determine if the LO oscillator is working.  If not, concentrate on the LO / converter stage.

If the LO is working, then why is the signal not passing through and reaching the audio stages of the radio? This is where you can get out your signal generator and start tracing a signal through, stage by stage.

Mark K8KZ


Messages In This Thread
Philco 640 - Need Some Help - by Geoff - 06-29-2016, 06:07 PM
RE: Philco 640 - Need Some Help - by Radioroslyn - 06-29-2016, 07:52 PM
RE: Philco 640 - Need Some Help - by Geoff - 06-29-2016, 08:05 PM
RE: Philco 640 - Need Some Help - by Geoff - 06-30-2016, 02:37 AM
RE: Philco 640 - Need Some Help - by Radioroslyn - 06-30-2016, 07:45 AM
RE: Philco 640 - Need Some Help - by Steve Davis - 06-30-2016, 10:06 AM
RE: Philco 640 - Need Some Help - by markmokris - 07-01-2016, 11:59 AM
RE: Philco 640 - Need Some Help - by Geoff - 07-01-2016, 04:00 PM
RE: Philco 640 - Need Some Help - by Geoff - 07-01-2016, 04:01 PM
RE: Philco 640 - Need Some Help - by Geoff - 07-01-2016, 04:02 PM
RE: Philco 640 - Need Some Help - by Geoff - 07-01-2016, 04:04 PM
RE: Philco 640 - Need Some Help - by Geoff - 07-01-2016, 04:10 PM
RE: Philco 640 - Need Some Help - by Geoff - 07-01-2016, 04:16 PM
RE: Philco 640 - Need Some Help - by Radioroslyn - 07-01-2016, 07:19 PM
RE: Philco 640 - Need Some Help - by Geoff - 07-01-2016, 07:20 PM
RE: Philco 640 - Need Some Help - by Radioroslyn - 07-01-2016, 08:19 PM
RE: Philco 640 - Need Some Help - by Geoff - 07-02-2016, 01:02 AM
RE: Philco 640 - Need Some Help - by Geoff - 08-04-2016, 06:39 PM
RE: Philco 640 - Need Some Help - by Geoff - 08-04-2016, 08:08 PM
Philco 640 Shadow Meter Bulb Type - by Geoff - 08-04-2016, 07:04 PM



Users browsing this thread: 9 Guest(s)
[-]
Recent Posts
RCA T62 is playing.....
Beautiful set.morzh — 09:07 PM
An attempt to remove the Field Coil from a G speaker
Well....here it is. The green stuff. Unfortunately, probably penetrates deep. I opened the top layer and saw that: ...morzh — 08:58 PM
Philco 91 Restore Code ??
:clap: :clap: :clap: :clap: Really nice workmanship!!! Top of the chassis looks great. Sorry about the long winded e...MrFixr55 — 08:09 PM
Philco 40-120C Restoration
Thank you for your reply. I will check voltages on the other tubes, look at resistor 23 and cap 25, etc. If all else fai...bluecap — 07:58 PM
RCA T62 is playing.....
Nice looking set great save. DavidDavid — 07:48 PM
Philco 89 indicator light.
Hello Jim, I have done several 89s. The trick is to move the drum in or out on it's shaft. You will need to loosen a set...dconant — 07:36 PM
An attempt to remove the Field Coil from a G speaker
MrFixr Yes, it is my plan to go with 45rpm spider if I go that far. No, the pole was not left-handed as I unscrewed ...morzh — 07:14 PM
Philco 40-120C Restoration
Change the tube. Check the tube's bias network. Are any other tubes experience the drop or just this?` Is resistor 23 OK...morzh — 07:09 PM
Philco 89 indicator light.
I forgot how the pointer is formed: could you show the way it is formed and how you tried to change it?morzh — 07:01 PM
An attempt to remove the Field Coil from a G speaker
Was that pole piece left handed ? Since the metal "spider" is toast, wonder if you can either get the "4...MrFixr55 — 06:54 PM

[-]
Who's Online
There are currently 8087 online users. [Complete List]
» 3 Member(s) | 8084 Guest(s)
AvatarAvatarAvatar

>