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

Hunting down the short in a Motorola 61CA
#10

I tried it with a 60 watt bulb in place and get a dim glow at 100+ volts (it starts around 85v or so). I kept a volt meter on the CT and after a couple of minutes the voltage was -9v and rising when I cut power. I've replaced the 41 with one of the 41s from my 46-280 set and warmup time should be reduced. All of the tubes test in the 70s or better on all tests at this point. I get a growl from the speaker when I touch the ungrounded side of the volume control with a soldering iron, so I'm guessing whatever the issue is, it is not necessarily in the output section.
Around 90 volts on the variac, I get a hum on the speaker that continues as I apply more voltage.

The only voltage other than the CT I took was the plate of the output which was pretty low, but Like I said, I haven't let the set properly warm up since I popped the small electrolytic cap. When I popped the 22f @50v cap previously, I did not replace the 10uf @ 500v or the 22 uf @ 450v caps. Do you think I might want to do that?

Or should I fire up the signal generator and start in with the grid of the 75 or 6D6?

Charlie in San Antonio


Messages In This Thread
RE: Hunting down the short in a Motorola 61CA - by ccomer1955 - 08-22-2015, 02:42 PM



Users browsing this thread: 1 Guest(s)
[-]
Recent Posts
trying to identify this wire type
The red wire is rubber covered wire. The others are cotton braid over rubber often in colors or a tracer, also strand...Chas — 02:43 PM
trying to identify this wire type
Greetings Phorum members, Hope you can help me identify this type of wire in the photo I have attached.  I am not sure ...georgetownjohn — 01:53 PM
Philco 60 Squealing
All correct shields must be in place, all tubes correct no subs of any kind. Check any soldered, riveted ground conne...Chas — 01:24 PM
Philco 60 Squealing
I have recapped and replaced out of tolerance resistors and so on. Radio plays nicely on fairly strong stations. The pro...dconant — 10:55 AM
Philco 46-420 Code 121 Reception issues
Welcome Eric, I agree with Bob and far as the two main electrolytic filter capacitors did you change them yourself or w...radiorich — 11:43 PM
Philco 46-420 Code 121 Reception issues
You mentioned the Philco manual and going through the check points...just to be sure we're on the same page here's the m...klondike98 — 08:13 PM
Philco 42-1008 conversion kit
Interesting. I haven't seen that before.klondike98 — 07:02 PM
12' Philco
Yes I had looked for it on the web as well some time back and could not find it. I was glad to see it turned up in Ron'...klondike98 — 06:59 PM
Shadow Meter Bulb
Now if you had a set with a tuning light then the bulb type is important to the circuit, some sets used those prior to t...Arran — 04:58 PM
Shadow Meter Bulb
Ok. Thanks for the correction.RossH — 03:09 PM

[-]
Who's Online
There are currently 5293 online users. [Complete List]
» 1 Member(s) | 5292 Guest(s)
Avatar

>