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

Hunting down the short in a Motorola 61CA
#6

My mistake. It is pins 4,5, and 6 of the 6D6 connected together and grounded to the chassis. Sorry. Old age caught me on the way downstairs to my computer, and I failed to re-read my original post where I have it right. So, as before, pin 3 of the 75 and pin 4 of the 6D6 connected by a .05 cap (C20?). So it looks like that isn't the issue?

I'm pretty positive I have the filter circuit done correctly: 22uf 450v runs positive to negative from pin 2 of the 80 to the CT, 10uf 500v runs positive to negative from pin 3 of the 41 to the CT, and 22 uf 35v runs positive to negative from the chassis to the CT.

Both dial lights light up, and the insulation on their wires looks intact. The on/off/volume pot shows 500K and the homage changes when I turn the knob (measuring from the middle lug to either outside lug). I get good continuity following the pathways for all of the top grid wires. And I can't find a short in the tuning cap, either. I tried the dim bulb test after I cleaned up a few busy solder points, and I still get a soft glow at about 75v that dims a bit, but steadily increases if I increase the voltage. By the time I get to about 100v, the light bulb has a steady moderate glow (not bright, but not dim, either).

If that is all correct about the filter circuit and the attempts to trace a short, then is there a methodology to narrow the search for a short, or should I just continue looking for mis-wiring and crumbling insulation (most of the wiring is cloth-wrapped)? Perhaps adding resistance along a bus and looking for numbers that are too large?

Charlie in San Antonio


Messages In This Thread
RE: Hunting down the short in a Motorola 61CA - by ccomer1955 - 08-20-2015, 11:33 PM



Users browsing this thread:
[-]
Recent Posts
Model 70 Cabinet Trim
musar , Well if you have any more questions feel free to post away . Sincerely Richardradiorich — 08:56 PM
Model 70 Cabinet Trim
Although I have not made any cabinets or cabinet parts for a couple of years, I still have some parts left over, includi...Steve Davis — 06:26 PM
philcorepairbench.com - shadow-meter
Thanks Ron.fenbach — 02:43 PM
Model 70 Cabinet Trim
Thank you, Gary. Before making my original post, I had clicked on "Steve Davis Cabinets" only to find that it...musar — 02:25 PM
philco predicta
Welcome to the Phorum, cgl18! I am not your resource for television repair, but lots of friendly help is available here...GarySP — 02:12 PM
Model 70 Cabinet Trim
Welcome to the Phorum, musar! You can send Steve Davis a private message (PM). The site is at the top of the Home page...GarySP — 02:09 PM
Model 70 Cabinet Trim
How do I contact him? The only contact information for him I could find when searching online was a telephone number th...musar — 10:38 AM
philco predicta
Hello, good afternoon, I would like to ask what the possible problem could be if I don't have an image on the screen. I ...cgl18 — 10:19 AM
Philco model 38 code 121 not receiving signal.
So one last question before I finish this radio. Regarding the speaker and output transformer. I salvaged the original o...Stormlord5500 — 09:31 AM
462ron
It’s on the bottom of the homepage of our Philcoradio.com homepage! Ron462ron — 07:20 AM

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

>