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Joined: Mar 2012
Posts: 2
W
New Guy
New Guy
W Offline
Joined: Mar 2012
Posts: 2
There's a hard tar-like substance under the power transformer of my Chevy model 986443 radio. I'd like to replace the transformer but can't find a suitable replacement (part number 7255881; 6.3V@6A, Sec. 650VCT .090 ADC).
Also need to replace switch on volume/tone control or the entire potentiometer with switch. Anyone know of a source for these? Thanks.

Joined: Mar 2002
Posts: 9,115
'Bolter
'Bolter
Joined: Mar 2002
Posts: 9,115
The controls for these radios are very hard to source. If the only problem is the switch, you could bypass it and put a toggle switch on the case somewhere. This could be a solution until you find a replacement switch. If you pull the controls from some other GM radios of the same vintage, you may find a switch that fits. The entire switch assembly has to come apart to get at the switch.

Why do you want to change the power transformer? They are normally encased in tar inside the tin.


1951 GMC 1 Ton Flatbed -- It is finally on the road and what a great time I have driving it!
1951 1 Ton Completed


My Chevy Master 4 Door is on the Road!
Joined: Nov 2000
Posts: 171
B
Shop Shark
Shop Shark
B Offline
Joined: Nov 2000
Posts: 171
53-54 Chevy passenger car is a good replacement power transformer ,I've also used Buick power transformers ,not an a direct replacement you will have to do some triming, 53-54 passenger push button radio , late 40's early50's Buick,Oldsmobile, 42-48 six tube Chevy radios the control can be used , carefully grind a flat spot on the shaft on the control, in my father's day there where replacement switches available I think from "GC",for those who did not want to spend the extra $1.50 for a OME control, CHANGE that buffer! that is what use to do in the power transformer and on/off switches

Joined: Mar 2012
Posts: 2
W
New Guy
New Guy
W Offline
Joined: Mar 2012
Posts: 2
I planned to change the transformer because some of the tar leaked out and hardened in the chamber under the transformer. There's a glob of tar about 2"x1.5"x .75". Fearing the windings might short without some of the tar, I haven't applied power to test. Thanks for the comments!

Joined: Apr 2002
Posts: 1,571
G
Shop Shark
Shop Shark
G Offline
Joined: Apr 2002
Posts: 1,571
The tar is there mostly to keep things from vibrating. Sometimes leaked tar is a sign of a shorted transformer, sometimes it just ran hot.


Get a REAL truck, get a GMC! www.oldgmctrucks.com
1954 GMC De Luxe COE

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