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

1936 Philco model 84 cathedral
#1



Hi Y'all, I'm a newbie to this forum! I am repairing/restoring a 1936 cathedral for my uncle, and it comes on but just hums. Is there anything I should know besides replacing the 8uF & 4uF power filter capacitor just to get any stations?

Do the RF coils need to be pulled and/or checked before I can receive any stations? It had a bad 77 tube (burned out heater) which is on order.
#2

All the caps in the bakelite blocks should be replaced and all resistor values checked and if off value changed ground on 77 tube checked.

vinzer
#3

I recommend replacing all the wax/paper capacitors as well.

Rod
#4

Lets not forget the feedback winding on the oscillator coil.
At least check it for continuity.
Terry

When my pals were reading comic books
I was down in the basement in my dad's
workshop. Perusing his Sam's Photofoacts
Vol 1-50 admiring the old set and trying to
figure out what all those squiggly meant.
Circa 1966
Now I think I've got!

Terry
#5

Awsome, awsome, awsome! Thank you all very much! Very good info. I was wondering if there were something inside those bakelite blocks. I just now acquired a schematic for this puppy and it shows those paper caps, but could not see them under the chassis! 8)

I was just checking the first coil which I believe (according to the schematic) is the antenna coil. It has good continuity. Which one is the oscillator coil?
#6

You have a # 77 tube with a lead off of it going to the oscillater coil.
#7

On my model 84 the osc coil is the center one and mine was open on thr outer winding.

Vinzer
#8

Best I remember the winding isn't critical as to the number of turns,about 20 of #30 to 36G should do it and if you wind it in the wrong direction you can just switch the wires that solder to lugs.
Testing
Look at the osc coil and you should see a 6000 ohm resistor and a mica cap (140mmfd) in parallel soldered to one of the lugs. Measure the resistance from that lug to chaiss ground. Should read only a few ohms (3-10) If it is higher pull it a rewind it.
Good Luck w/it
Terry

When my pals were reading comic books
I was down in the basement in my dad's
workshop. Perusing his Sam's Photofoacts
Vol 1-50 admiring the old set and trying to
figure out what all those squiggly meant.
Circa 1966
Now I think I've got!

Terry
#9

Forgot to mention you said that you measured the antenna coil. Very important that when you check the primary that you have the volume turned up all the way. If you don't then you might be measuring just the volume control not the coil.
Testing
Measure from ant post to ground with volume up and set unplugged. Should be a low resistance like 5-20ohms. If it's up in the 1000's rewind it. The may play with the primary open but it will play much better with it intact. I'd go with 20 or 30 turns of 30-36G wire (not critical).
Terry

When my pals were reading comic books
I was down in the basement in my dad's
workshop. Perusing his Sam's Photofoacts
Vol 1-50 admiring the old set and trying to
figure out what all those squiggly meant.
Circa 1966
Now I think I've got!

Terry




Users browsing this thread: 1 Guest(s)
[-]
Recent Posts
Philco 91 Speaker Replacement
The spider is glued on the cone and so is the voice coil. I think you can use a cotton swab dipped in acetone and carefu...RodB — 02:42 PM
Restoring Philco 37-604C
Yes I saw that. If I knew, I'd probably try to arrange for getting it myself. But I have just got one. Which does not m...morzh — 01:44 PM
Philco 38-2 Automatic Tuning
When you push the lever, you are supposed to rotate the disk to the desired station. Then the magnetic tuning will acqu...morzh — 01:42 PM
Philco 38-2 Automatic Tuning
I figure out the muting from another picture that helped. Now I need to know how the automatic tuning works. When I push...dconant — 12:11 PM
Philco 91 Speaker Replacement
How would I go about removing the spider from the cone?dconant — 12:04 PM
Philco 38-2 Automatic Tuning
Hello, I am having trouble getting my automatic tuning to stay unmuted. If I play with the tuning handle I can get it to...dconant — 10:51 AM
Does anyone make photofinish replacements?
Here’s the link to the DIY photofinish section of our site: klondike98 — 09:46 AM
Delco car radio Peko vibrator converstion issues
Hi Richard, Thx for posting the schematic.  As I remember as a kid, these were great performers for the time, likely...MrFixr55 — 08:56 AM
Delco car radio Peko vibrator converstion issues
hello mr Fixr, The Electro  Powersupply that I am powering the radio with has a huge choke plus a 10,000ufd electrolyti...radiorich — 10:58 PM
Delco car radio Peko vibrator converstion issues
How about putting a choke in the power supply? The big cap was likely an attempt to stabilize the DC. Kids who cre...MrFixr55 — 09:19 PM

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

>