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  #61  
Old 09-26-2018, 06:01 PM
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I think different measuring devices will give different results. Fingers crossed for good results. We have a way to go. Going into these old sets and restorations is taking a leap of faith. We are 2000 miles from the ETF. We inquired prior to the auction, did our due diligence and hope for the best. There are no guarantees, go big, use our best judgment and hope to be rewarded with a sweet set.

About the convergence transformer that needs to be replaced, is the convergence transformer for the Westinghouse the same as that of the other early color chassis with 15GP22 CRT?

I don't know. I’m assuming no. Westinghouse did not necessarily follow RCA with their designs. I contacted John.
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Last edited by etype2; 09-26-2018 at 06:09 PM. Reason: Typo
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  #62  
Old 09-27-2018, 10:06 AM
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Quote:
Originally Posted by etype2 View Post
I think different measuring devices will give different results. Fingers crossed for good results. We have a way to go. Going into these old sets and restorations is taking a leap of faith. We are 2000 miles from the ETF. We inquired prior to the auction, did our due diligence and hope for the best. There are no guarantees, go big, use our best judgment and hope to be rewarded with a sweet set.

About the convergence transformer that needs to be replaced, is the convergence transformer for the Westinghouse the same as that of the other early color chassis with 15GP22 CRT?

I don't know. I’m assuming no. Westinghouse did not necessarily follow RCA with their designs. I contacted John.
The part is exactly the same as that used on the RCA CT-100. Westinghouse had to source the CRT, along with the yoke, convergence hardware, etc, from RCA.
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  #63  
Old 09-27-2018, 12:01 PM
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IIRC at the dawn of radio RCA was formed as a patent pool/consumer radio products division between GE and Westinghouse...There was probably still some corporate friendship between them at the time.
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  #64  
Old 09-27-2018, 02:01 PM
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IIRC at the dawn of radio RCA was formed as a patent pool/consumer radio products division between GE and Westinghouse...There was probably still some corporate friendship between them at the time.
I don't believe the relationship between RCA and Westinghouse really had much to do with it. In fact, I recall reading that David Sarnoff was annoyed that Westinghouse had beat RCA to the punch with the H840CK15. Not that it really mattered; nobody was buying color sets anyway.

I think this is more an issue of the ONLY tube being available for Westinghouse to start constructing color sets with was the RCA 15GP22, and thus some hardware would have to be the same among all of the 15 inch color sets.

Before someone mentions the CBS 15HP22 as an option that Westinghouse could have explored for the H840CK15, those tubes appear to have been engineering samples only, though there is evidence that one of the 15HP22s at the museum was installed in a stock Westinghouse set. I have to wonder, if CBS had placed the 15HP22 into production in the same manner that RCA did the 15GP22, would manufacturers have adopted it right away and abandon the RCA tube? I think it's safe to hazard a guess of "absolutely" given how eager they were to adopt the 19VP22 and 21AXP22, albeit probably more for reasons of size.

I think it's also rather telling that Westinghouse rolled out a 19 inch model rather quickly, as did Motorola, abandoning the RCA tube for the CBS tube. Then, Westinghouse utilized the 22EP22 in 1957, which I assume has some relationship to the CBS rectangular tube, before finally moving back to the RCA color tubes with a short-lived model in '57 or '58 using the 21CYP22.
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  #65  
Old 10-02-2018, 05:44 AM
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UPDATE, OCTOBER 2, 2018
Hi Marshall. I spent some time this evening working on the distressed wiring in the High Voltage cage. The purpose of the “wiring fix” is to allow me to test the circuit as designed before I make any modifications during the restoration process. The wiring fix involved “putting back” some of the wires that had simply fallen off of places from age and from the “trip”. Anyway, I am now able to confirm that the flyback is “alive” at least to the point of generating High Voltage. I got 20 KV on the final anode lead with the regulation tube disconnected. Obviously this is a critical thing to verify early on in the restoration process. It is now time to test and replace tubes and then look at a bunch of other signals with the oscilloscope as we proceed. It is also time to start replacing a lot more capacitors. At some point, probably very soon in the process, I will return to the High Voltage section and do some more work there. But this test verifies a lot of components like the “doorknob” capacitors and insulators in the High Voltage section.
YAY!!
Mike
Author: Great news!

Link: https://visions4netjournal.com/westinghouse/
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  #66  
Old 10-02-2018, 04:58 PM
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Hi Mike and VK members,

Great news. I think the nominal ultor voltage for this set is 19.5 KV?

I’m told the convergence transformer in question is identical to RCA.

Best,

Marshall

Yes, that is what the nominal HV should be at the 2nd anode. The actual HV generated should be, I think, more like 22.5kv or more. This is due to the function of the 6BK4 Shunt Regulator that keeps the regulated voltage at the 2nd anode at roughly 20KV at all brightness levels. The overhead voltage is so the shunt regulator can do that job at different beam currents. I made this test with no shunt regulation at all. I believe that the initial HV will come up quite a bit after some recapping and tube replacements like the 6BG6 Horizontal output tubes. I still have to go through the tubes and test them all. But this tells me that it is now OK to move forward with the whole project.

Can you go ahead and arrange the convergence transformer purchase? Or are there none left to be purchased? Do I have to build one?

Cheers, Mike


Mike,

I’m glad that we can continue to proceed with the restoration! :-) I’m not sure what the issue is with the transformer. A VK member said “The dynamic convergence transformer is T-701. It needs to be replaced with a Folsom reproduction ASAP, before you damage pots in the focus circuit.” Further, its the same as used in the RCA CT-100. Apparently the part is near impossible to find if bad.

Another VK member said it’s doubtful that John Folsom has a replacement because the last one was sold to a collector. I contacted John a week ago with no response, perhaps my mail went to his junk folder as I haven’t corresponded with him in quite some time.

We don’t know if our transformer is bad? It’s called the vertical convergence transformer T-701. When you reach that point you can test, no? I will post this on VK.

Cheers,
Marshall
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  #67  
Old 10-02-2018, 05:47 PM
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I believe that transformer is both vertical output and convergence. The convergence is high voltage, and the failure mode of the transformer is breakdown of the insulation of the HV convergence winding and the other windings. The current drawn when it shorts damages NLA/unobtainium parts like the focus pot.
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  #68  
Old 10-02-2018, 06:30 PM
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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/#
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Last edited by etype2; 10-03-2018 at 02:53 PM.
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  #69  
Old 10-07-2018, 06:10 PM
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VDC transformer

After further testing Mike found the VDC transformer open. Thanks to Ben for the heads up.
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  #70  
Old 10-07-2018, 06:27 PM
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Out of curiosity, which winding was open on the VDC?
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  #71  
Old 10-07-2018, 08:29 PM
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Both secondary windings are open.
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  #72  
Old 10-08-2018, 03:17 PM
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Originally Posted by etype2 View Post
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.
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  #73  
Old 10-08-2018, 05:59 PM
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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.
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Last edited by etype2; 10-08-2018 at 06:47 PM.
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  #74  
Old 10-09-2018, 08:59 AM
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Would you please share the link to John's write up?
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  #75  
Old 10-09-2018, 12:23 PM
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Hear you go. On the ETF site.

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Last edited by etype2; 10-09-2018 at 02:06 PM.
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