Westinghouse K840CK15 Restoration

[etype2]

Thanks for that Tom. Just received another email from Mike. He remembers the issue from reading about it in the past. He understands the issue and has rewound transformers in the past. He has the materials to rebuild and equipment to test a rebuilt transformer.

If John has one available, we would like to purchase one and avoid the tedious work. I think Mike is going to contact John directly. On the bright side we may have a good transformer, but it wouldn’t hurt to have a spare.

UPDATE, OCTOBER 3, 2018

Let’s add clarity

OK. I have studied 3 different schematics.

The Photofact for CT100 RCA calls for a primary transformer DC resistance of 1200 OHMS There are 2 secondaries. Secondary #1 calls for 1800 OHMS and secondary #2 calls for 7200 OHMS.
The Photofact for Westinghouse chassis calls for Primary DC resistance of 1000 OHMS. Secondary #1 is 3200 OHMS and secondary #2 is 3800 OHMS.
Westinghouse factory schematics calls for Primary DC resistance of 1000 OHMS. Secondary #1 is 1350 OHMS and secondary #2 is 375 OHMS.
I realize that these are DC resistance values and the actual IMPEDANCE for the components is not really called out on the schematic. BUT, these numbers should agree to a much greater degree of precision before I believe that the RCA part is the same as the Westinghouse.
I ran out of time tonight but I will be doing DC resistance checks tomorrow night in an effort to sort this out.
Stay tuned!
Mike.
Link: https://visions4netjournal.com/westinghouse/#

[benman94]

Originally Posted by etype2

Thanks for that Tom. Just received another email from Mike. He remembers the issue from reading about it in the past. He understands the issue and has rewound transformers in the past. He has the materials to rebuild and equipment to test a rebuilt transformer.

If John has one available, we would like to purchase one and avoid the tedious work. I think Mike is going to contact John directly. On the bright side we may have a good transformer, but it wouldn’t hurt to have a spare.

UPDATE, OCTOBER 3, 2018

Let’s add clarity

OK. I have studied 3 different schematics.

The Photofact for CT100 RCA calls for a primary transformer DC resistance of 1200 OHMS There are 2 secondaries. Secondary #1 calls for 1800 OHMS and secondary #2 calls for 7200 OHMS.
The Photofact for Westinghouse chassis calls for Primary DC resistance of 1000 OHMS. Secondary #1 is 3200 OHMS and secondary #2 is 3800 OHMS.
Westinghouse factory schematics calls for Primary DC resistance of 1000 OHMS. Secondary #1 is 1350 OHMS and secondary #2 is 375 OHMS.
I realize that these are DC resistance values and the actual IMPEDANCE for the components is not really called out on the schematic. BUT, these numbers should agree to a much greater degree of precision before I believe that the RCA part is the same as the Westinghouse.
I ran out of time tonight but I will be doing DC resistance checks tomorrow night in an effort to sort this out.
Stay tuned!
Mike.
Link: https://visions4netjournal.com/westinghouse/#

The DC values listed on the Sam's Photofacts for both the Westinghouse and RCA are in relatively close agreement. The values given in the Westinghouse service information are extremely low. When you're measuring a DC resistance of the same part, in examples of the same model set, and one of those values is extremely low compared to the other, that's a pretty decent indication that the low reading values were taken with a simple VOM, and the higher values with a VTVM.

In any case, the discrepancy doesn't matter. If you had read John's write up of the new transformer you would see that they've been used in CT-100s, 15 inch Westinghouses, a 15 inch Motorola, etc.

Any differences that may exist between the two parts are too small to make any difference in circuit.

[etype2]

Originally Posted by benman94

If you had read John's write up of the new transformer you would see that they've been used in CT-100s, 15 inch Westinghouses, a 15 inch Motorola, etc.

We found this to be true. Can you direct us to John’s write up? Is it in this forum?


Edit: I found it.