Welcome Guest! Be sure you know and follow the Phorum Rules before posting. Thank you and Enjoy! (January 12) x

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

New here, an 89B I'm repairing
#4

Sparkydave, you might first check the feedback winding of the oscillator coil in series with the 36 tube cathode. This winding is notorious for opening up as it is wound on the outside of the main coil with a nitrocellulose insulating sleeve. The nitrocellulose decomposes over time, releasing nitric acid and corroding the copper wire. This is the usual cause of osc failure in the 89/19 moder radios.

Check the voltage on the cathode of the 36, If it is more than a few volts, them the winding is probably open. It is fairly easy to rewind this section of the coil to restore operation.


Messages In This Thread
New here, an 89B I'm repairing - by sparkydave - 06-20-2014, 08:45 PM
RE: New here, an 89B I'm repairing - by Mondial - 06-20-2014, 09:47 PM
RE: New here, an 89B I'm repairing - by gregb - 06-20-2014, 09:49 PM
RE: New here, an 89B I'm repairing - by morzh - 12-01-2014, 04:38 PM
RE: New here, an 89B I'm repairing - by AI2V - 12-01-2014, 06:12 PM



Users browsing this thread: 1 Guest(s)
[-]
Recent Posts
1930s Stewart-Warner Tombstone Radio need help identifying model number
Another Update: I found a couple of damaged coils inside this radio that might have something to do with why this radio ...captainclock1988 — 10:51 PM
6TPZ and 5TPO Radio Help
If you are still on 5TPO, you lost me there. What X7? What Points 1 and 2?morzh — 08:37 PM
6TPZ and 5TPO Radio Help
Quick progress report: X7 is broken. Only one leg soldered, the other missing and the diode is cracked. I've replaced...R3Sons — 05:05 PM
6TPZ and 5TPO Radio Help
Oh...and you have electrolytic caps there. All need to go and be replaced.morzh — 04:36 PM
6TPZ and 5TPO Radio Help
Thanks, will do.R3Sons — 01:25 PM
1930s Stewart-Warner Tombstone Radio need help identifying model number
UPDATE: I was able to pick up a signal generator on the cheap (amazingly enough) on feebay and I did an IF alignment fol...captainclock1988 — 09:53 AM
Philco 91 Schematic
Hi Rod, The resistor connects to pin 4 and the ungrounded side of block 9. From pin 9 of the RF tube to one side of ...dconant — 09:34 AM
Just got a 49-1613 need to know...everything!
I just found your post. I have this exact same model, and have had it since 1985 when I was 15 years old! I performed a ...MuzzcoVW — 09:11 AM
B&K 1077B no video
Hello Tim, I would if it's a leaky Capacitor So are all 3 of those B- voltages low then ? Sincerely Richardradiorich — 01:55 AM
B&K 1077B no video
I found a schematic and think I have the problem traced down to the minus power supply. I have very low voltages that go...TV MAN — 12:41 AM

[-]
Who's Online
There are currently 4322 online users. [Complete List]
» 1 Member(s) | 4321 Guest(s)
Avatar

>