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

3116X issues
#1

I am having an issue with the 3116 (116) I recently restored. It has been fully recapped, including all paper and electrolytic, plus three micas. All out-of-tolerance resistors changed, along with the Candohm. It plays beautifully, very good sound, selectivity great, nice tone. But...at low volume levels, there is a "clicking" noise. And, I have 64 volt AC on the chassis, measured to ground. I found this problem, after getting a small shock. And to top it off, if I connect a ground lead to the chassis, the audio develops a hiss and distortion, which stays even after I disconnect the ground. I need to shut off the set, and let it cool down, to get the audio back to normal. 

-I have eliminated the tubes as the issue; swapped all, one at a time, for known good ones. 

-Performed a dim-bulb test on the power transformer. All tubes/dial lamps removed. No glow with no load. And the voltage on the chassis is gone as well.

-"click" noise present with RF/IF sections disconnected. So, assuming it might be the audio output transformer, I checked it...no shorts detected. Even swapped an identical speaker assembly...same issues.

So...before I go and start ripping the chassis apart, or ripping out my hair, has anyone run into an issue like this? Steer me in the right direction?


Attached Files Image(s)
   
#2

if you have 64VAC on the chassis (I take it you mean the Earth GND that you measured it in reference to) this could mean:

1. Capacitive divider 131 from L and N to chassis. This is normal. If you connect a say 10K resistor from it to GND it should go to zero.
2. Check your caps there for the value. 0.015uF is plenty. If you put some larger value - replace.
3. Simply ohm out the input plug to chassis, see if there is some finite resistance there.
4. A capacitive coupling to the chassis via transformer also could make 6oV but it should be extremely weak and not cause any feelings when touched.
5. Check the transformer for leakaga. (same as in bullet 3)

As for the clicking noise....short of pulling the output tubes, see what tube pulling stops it. if does not, pull the output tubes, one by one. Always leave one tube in.

People who do not drink, do not smoke, do not eat red meat will one day feel really stupid lying there and dying from nothing.
#3

Thanks for the help, morzh! I forgot to mention that I did pull the tubes, and the "clicking" is still present, unless I pull out the 42 .

But I got the probe I was building for my Eico signal tracer finished, and low and behold...the clicking noise comes through on the tracer, without the radio plugged in. So, I did some checking, and the noise is on the power line to my basement shop! But not present anywhere else in the house. My shop is on a sub panel, so that may be a cause. I have a my personal Sparky on the case. He thinks it may be an induced noise, from another line that crosses the supply to my panel. We'll see...

I may have isolated the voltage issue, however, after I followed your advice. I believe I may have a leaking mica cap, off the grid of the 77 tube.




Users browsing this thread: 1 Guest(s)
[-]
Recent Posts
Philco Model 38-7: what caps & resistors do fail typically?
Since you stated earlier, you have a console 38-7XX.  They also had a 38-7T (table), and 38-7CS (chairside).  A very nic...GarySP — 01:18 PM
Part numbers to model cross
That I wouldn't know, but sometimes the radio document itself shows one, same as the capacitor cans' etc pinouts.morzh — 12:46 PM
Part numbers to model cross
Thank you morzh, that is exactly what I was looking for. Now , is there some where that shows pinouts for Philco power ...Jim Dutridge — 11:37 AM
Restoration of the Canadian General Electric A-87
Thanks for your help Michael. In fact, this video is only an intermediate result. Later I had to apply another tinting l...RadioSvit — 09:01 AM
Restoration of the Canadian General Electric A-87
Great job on the cabinet. PS. In the US notation, "kenotron" refers to specific type of tubes; we call re...morzh — 08:24 AM
Part numbers to model cross
This document has at least some tables of models and parts used. Example: Choke 32-7572, used in 604 radio. Search f...morzh — 08:19 AM
Restoration of the Canadian General Electric A-87
I also checked all the radio tubes on my Hickok 530 tube tester. The 5Z3 kenotron turned out to be faulty, all the other...RadioSvit — 08:02 AM
Restoration of the Canadian General Electric A-87
Well... While the varnish is drying up, I started repairing the chassis... Of course I started by replacing the pa...RadioSvit — 07:12 AM
Philco Model 38-7: what caps & resistors do fail typically?
Hello Martin, Welcome aboard our little community what great Model 38-7 Sincerely Richardradiorich — 12:30 AM
Philco Model 38-7: what caps & resistors do fail typically?
Welcome to the Phorum Martin. I count about 9 paper caps, the 3 electrolytic caps and 2-Y2 safety caps to replace th...RodB — 09:44 PM

[-]
Who's Online
There are currently 1340 online users. [Complete List]
» 1 Member(s) | 1339 Guest(s)
Avatar

>