Hunting down the short in a Motorola 61CA

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

Linear Mode

Hunting down the short in a Motorola 61CA

Radioroslyn
Phorum Expert

Posts: 7,297
Threads: 268
Joined: Dec 2009
City: Roslyn Pa

08-20-2015, 10:13 PM

What 20 does is provide a RF ground for the ant coil and the secondary of the IF transformer. If you follow that buss it ends up at the 75 tube diode this provides the - DC voltage which controls the gain of the two circuits (ant and IF).This is called AVC automatic volume control or AGC automatic gain control. The more signal at the anttena the more - voltage that is developed. The more - voltage on the AVC line the less gain the mixer and IF amp will have.
Bottom line is if 20 was shorted the set would work fine but would not have any AVC action. If it was open then it creates a problem of low gain.

Pin 3 of the 6D6 (screen grid) should have hv on it and NOT be connect to the other pins. If 3 is hooked to other pins that's your short!

Terry

(This post was last modified: 08-20-2015, 10:14 PM by Radioroslyn.)

Find

« Next Oldest | Next Newest »

Thread Closed

Messages In This Thread

Hunting down the short in a Motorola 61CA - by ccomer1955 - 08-20-2015, 01:03 PM

RE: Hunting down the short in a Motorola 61CA - by ccomer1955 - 08-20-2015, 02:37 PM

RE: Hunting down the short in a Motorola 61CA - by Radioroslyn - 08-20-2015, 06:22 PM

RE: Hunting down the short in a Motorola 61CA - by ccomer1955 - 08-20-2015, 07:01 PM

RE: Hunting down the short in a Motorola 61CA - by Radioroslyn - 08-20-2015, 10:13 PM

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

RE: Hunting down the short in a Motorola 61CA - by Steve Davis - 08-21-2015, 12:26 AM

RE: Hunting down the short in a Motorola 61CA - by ccomer1955 - 08-21-2015, 10:57 AM

RE: Hunting down the short in a Motorola 61CA - by Steve Davis - 08-21-2015, 10:36 PM

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

RE: Hunting down the short in a Motorola 61CA - by ccomer1955 - 08-22-2015, 08:45 PM

View a Printable Version

Users browsing this thread: 1 Guest(s)

Recent Posts
Zenith H725
I think the problem is traced - to noise on the AC line. It sounded so local, that it seemed certain it was generated wi...EdHolland — 05:51 PM
The list of my radio & TV collection!
A little bit of positivity in our feed... My new video... Test - the Philco 16B vs Philco 37-116 de Luxe / Test - the ...RadioSvit — 12:14 PM
Refinishing Ideas
Thanks. I will look into. Billpoulsbobill — 11:23 AM
My Philco 37-116 Restore
Why do the flood lights have 2 wires running to the shell of each light when the inner conductor only has one to each? ...dconant — 10:54 AM
Philco 46-480 Electronic Restoration
OOPS!! if there is a "flag" running up the side of the tube that touches the shield, then yes, a shield belon...MrFixr55 — 10:03 AM
Philco 46-480 Electronic Restoration
Thanks for pointing out that shield! I will try to find out where else it may belong. I simply installed it back where i...jrblasde — 10:02 AM
Philco 46-480 Electronic Restoration
Very nice job. A real contrast between how easy the main chassis is to work on, vs how tightly the RF chassis is packed...MrFixr55 — 09:31 AM
Philco 46-480 Electronic Restoration
After sleeping on it, I believe the issue is that I may have forgotten to install a ground connection between the RF cha...jrblasde — 09:21 AM
Refinishing Ideas
Hi Poulsbobl, I think that you could get away with it. In the Philco Library, there is a parts listand specs for sp...MrFixr55 — 11:54 PM
Philco 46-480 Electronic Restoration
The sleeving for the transformer arrived early, so I went ahead and finished reassembling. The chassis looks far better ...jrblasde — 10:15 PM

Who's Online

There are currently 1602 online users. [Complete List]
» 3 Member(s) | 1599 Guest(s)

Login
Username:
Password:	Lost Password?
	Remember me