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

Troubleshooting Open Coils - Philco 84B
#1

Hi fellow members-
I am new to radio restoration but have been quickly learning about the process (although I have restored a couple of cars). I purchased a Philco 84B as my first project and am currently replacing the caps, resistors, and bakelites. I am slightly confused about troubleshooting the coils. For the oscillator and antenna coils, I get very low resistance values (2-8 Ohms) while checking continuity. I cannot locate the theoretical values and am hoping these are high enough values to indicate working coils(??)...does anyone know where can I locate these values for an 84? Also, the voice coil and output transformer shows OL so they appear dead. How do you guys figure out if these are good or need rewinding if you get values which are not OL or very high? Should I just assume they are OK and proceed with the rebuild? Thanks for your help-
-The schematic is attached
bdi


Attached Files
.pdf Philco84B Schematic.pdf Size: 107.45 KB  Downloads: 229
#2

Hi, welcome to the Phorum!

Exact resistances of the rf/if coils aren't important, as long as they aren't open. Your range of 2-8 sounds fine.

The field coil should measure 1140 ohms, the primary of the output transformer should be 400 ohms, and the voice coil .9 ohm. If any of those are substantially off or open, the radio isn't going to work. The speaker can be replaced with a modern one, and output transformer, and a resistor close to 1140 ohms at 20-25 watts or so. Hum may be increased without the field coil acting as a choke.


Good luck!

Will




Users browsing this thread: 1 Guest(s)
[-]
Recent Posts
Philco 42-390, code 121 speaker
#87 on the schematic.  This radio had a 8" Zenith  speaker attached to it when I got it. I do don't know the hist...Stevelog — 06:39 PM
Philco 60 Squealing
I'm pretty sure I now have the litz wire soldered. This did not make any difference. Back in April I rewound the seconda...dconant — 06:25 PM
Philco 38-7 Speaker
Just to make sure, you chose either 4 ohm into 5K or into 10K? (blk-org or blk-grn)morzh — 06:23 PM
Philco 38-7 Speaker
I have let this one sit because of other duties. Now I am back, and I have a couple of questions. I hooked up a Hammond ...tludka — 05:34 PM
Philco 42-390, code 121 speaker
>>A closer examination of the very small print schematic indicates that the speaker is a PM type. This shows a ...morzh — 05:18 PM
Philco 60 Squealing
Litz is typically tinned by simply rubbing it with the soldering iron tip while immersed in solder (and a bit of rosin f...morzh — 05:14 PM
Philco 6K7
The suppressor grid (if by G3 you mean the S) is usually at the Cathode potential, which in this caes is GND. I am not ...morzh — 05:10 PM
Philco 16B Parts
Thanks for the reply. Unfortunately the radio was removed before bidding was over so I didn't get a chance to bid.dconant — 04:10 PM
Philco 16B Parts
Hi Dan, Mike is correct, there's a lot of painted stuff on the chassis but it looks pretty good. The sm is all there,sp...Radioroslyn — 03:50 PM
1930s Stromberg-Carlson Tombstone Radio need help identifying model number
Hi Cap'n Clock, Unfortunately, I do not have this radio.  This is a shame because this should be a good performer.  2A...captainclock1988 — 03:43 PM

[-]
Who's Online
There are currently 2981 online users. [Complete List]
» 1 Member(s) | 2980 Guest(s)
Avatar

>