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

38-5 volume problem
#16

(12-17-2014, 07:38 PM)r8i0 Wrote:  
(12-17-2014, 07:07 PM)Mike Wrote:  Welcome to phorum. Did you by chance get around to checking the grid cap leads as mentioned by Aaron?

Hi Mike
I cleaned the grid caps and the connectors and still have the problem. I Just replaced the 6f6 tubes again no solution.

Almost 30 years repairing radios and this is one of the toughest.
r8i0

It isn't just a matter of cleaning them, sometimes they need to have the joint re-soldered, the lead due to internal breakage, and the cap itself due to a deteriorating solder joint.
Regards
Arran
#17

    Bill, you've got a lot more experience than I do so I doubt I can help much, but I feel your pain.  I've got an 84B that has a similar volume jumping around problem that I've yet to diagnose.  I've prodded for loose components; looked for cold solder joints;  cleaned dirty pots and tube pins but haven't located
[/quote]

Good evening,
Earlier today I replaced the pair of 6f6 tubes with a pair of 6v6 tubes and the problem got worse. The bounce went crazy. Big highs and low lows. I am going to concentrate on the output for now and will report the results.
R8i0
[/quote]

Well, I think that I finally found the problem. I decided to replace ALL the resistors in the radio and found that in an earlier repair they put a .01 on the grid of the 6J5 and the schematic called for a 110mmf. I replaced this cap and the radio is playing at a nice steady volume for about 30 minutes now. I'll play it for another hour or so and if it is still good I'll call it done. I will check the alignment again and then put it back in the cabinet. I will then try to send a picture of it completed.
Thanks to all who helped with this fix. Merry Christmas.
#18

Congrats!! 
110pF.....0.01uF....someone missed a few decimal points on that conversion Icon_lol  Glad you found the problem.
#19

I wonder why the volume was bouncing....unless it was a phaseshift created by the cap since the triode is part of the AVC which is a neg. feedback so it got to oscillate....




Users browsing this thread: 5 Guest(s)
[-]
Recent Posts
An attempt to remove the Field Coil from a G speaker
Paul, thanks, Anything can help. Gary Thanks, lemme look! PS. Looked it up. They have kits and parts for mod...morzh — 02:45 PM
An attempt to remove the Field Coil from a G speaker
Paul, thanks, Anything can help. Gary Thanks, lemme look!morzh — 02:39 PM
46-1201 Trip Switch Spring
I deleted the other thread, as it was duplicate and did not have the photo. Please proceed with this one.morzh — 02:37 PM
46-1201 Trip Switch Spring
Hello, first post here, bear with me. I've been electronically refurbishing a 46-1201 that I received from a relative. ...ConcernedFeller — 01:46 PM
An attempt to remove the Field Coil from a G speaker
I am late to this post, amazing amount of work for a speaker Mike. You must like the challenge. I have a speaker from an...Paul Philco322 — 01:04 PM
An attempt to remove the Field Coil from a G speaker
Mike, give this site a look for your spider. Can't hurt. Take care and BE HEALTHY! -GaryGarySP — 12:41 PM
An attempt to remove the Field Coil from a G speaker
Rod, Bubble packaging? The one I know (if you mean the large bubble type) is really thin. I have some at home. Is there...morzh — 12:23 PM
An attempt to remove the Field Coil from a G speaker
Q8. What's the meaning of life? I have read that someone made a spider out of the clear plastic from bubble packagin...RodB — 11:07 AM
An attempt to remove the Field Coil from a G speaker
So, Q1. Does anyone know where to get the spider. Q2. If there is no such place, what material is best? I doubt tin is...morzh — 09:43 PM
An attempt to remove the Field Coil from a G speaker
Arran The oxidation seems to go deep, a few layers. The break starts right there, but then it will occur on every la...morzh — 07:35 PM

[-]
Who's Online
There are currently 8422 online users. [Complete List]
» 1 Member(s) | 8421 Guest(s)
Avatar

>