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 Post subject: Philco flyback transformer replacement
PostPosted: Apr Thu 02, 2020 4:22 am 
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Joined: Apr Thu 02, 2020 4:15 am
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Please help trying to find a replacement horizontal output transformer for my Philco 51pt1207 I've been searching for wel over a year now Any info or advice would be appreciated.


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 Post subject: Re: Philco flyback transformer replacement
PostPosted: Apr Thu 02, 2020 4:49 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 26122
Location: Detroit, MI USA
Have you tried Moyer Electronics in PA? They are normally the go to source for vintage flybacks and yokes.

You might also want to put an ad over on the ETF classifieds.
https://www.earlytelevision.org

Some parts which were set specific can be extremely difficult to locate 70 years later. It can be helpful if you provide the original part number from the manufacturer's service data with all inquiries, so that cross references to possible aftermarket replacements can be looked up.

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Experience is what you gain when the results aren't what you were expecting.


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 Post subject: Re: Philco flyback transformer replacement
PostPosted: Apr Thu 02, 2020 5:42 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 9480
Location: Redlands CA
Sam's has no listing for an aftermarket replacement as of the 1951 publication date.

I'm familiar with this set because I have one, it's a rare bird with a weird CRT. I'm thinking there were other 12" sets from the same time that used regular CRT's and possible the same Flyback, though I don't know what they are, maybe not because the Yoke is one of a kind?

It shouldn't be too hard to look through Sams from the same year and see if any other chassis look similar.

Are you certain it's bad? It's not all that common for the Fly to go bad in the old B&W sets, other than physical damage from Rats or Moisture.


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 Post subject: Re: Philco flyback transformer replacement
PostPosted: Apr Thu 02, 2020 7:34 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 1439
Location: 07450, New Jersey
When searching for a component it is always helpful to include the part number you are searching for as that is how parts are identified.

I looked up the Sams for the 51-PT1207 and it is on the ETF website. http://www.earlytelevision.org/pdf/phil ... 136-12.pdf

The part number given for the Horizontal Output transformer is 32-8466. Looking in the Merit cross reference shows that the Merit HVO-7 is a sub for this part number. The notes indicate there is a mounting difference, need to use the instructions included, and to use the Merit Width and linearity coil MWC-1.

The Thordarson cross reference catalog does not list a replacement.

I have an HVO-7 available but not the MWC-1
I found an MWC-1 available in this auction: https://www.ebay.com/itm/Radio-TV-Parts ... xyxpxQ6pZv

The Early Television Foundation has both according to their list. https://docs.google.com/spreadsheets/d/ ... ingle=true

You can send an email to them at: info AT earlytelevision.org to inquire. Parts there can be had for donations. There may be a slight delay in a response as they are going through a major renovation.

I hope all this helps.

Regards,

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Tim

"One of the advantages of being disorderly is that one is constantly making exciting discoveries." A. A. Milne


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 Post subject: Re: Philco flyback transformer replacement
PostPosted: Apr Thu 02, 2020 1:53 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 2070
Location: Lafayette, CO
I have one of those sets that was upgraded to a 12KP4. I believe both the yoke and flyback were changed, too. Why do you think you need a flyback for that chassis? Craig


Last edited by analog.tv on Apr Fri 03, 2020 2:42 pm, edited 1 time in total.

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 Post subject: Re: Philco flyback transformer replacement
PostPosted: Apr Thu 02, 2020 2:33 pm 
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Joined: May Sun 07, 2017 11:35 am
Posts: 916
Location: Belrose, NSW, Australia
Re the ETF:
Quote:
There may be a slight delay in a response as they are going through a major renovation.

I hope they are doing something about the flammability of that building.

I was there on a hot day about 6 years back and the smell of hot bitumen and timber got me worried.
The building used to be a railway freight depot.

To lose that collection just doesn't bear thinking about.

_________________
Wax, paper, bitumen, cotton, high voltages - what could possibly go wrong?


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 Post subject: Re: Philco flyback transformer replacement
PostPosted: Apr Mon 06, 2020 12:10 pm 
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Joined: Jan Thu 16, 2020 12:29 am
Posts: 569
BakeliteBlast wrote:
Please help trying to find a replacement horizontal output transformer for my Philco 51pt1207 I've been searching for wel over a year now Any info or advice would be appreciated.


I think you might be a little like Tom Hanks, cast away on an island for some years waiting to be rescued by a ship, or a replacement part in this case. At this point you should assume there is no rescue & no replacement. But like the character in the movie, you can choose to take the risk and leave the island to solve your problem.

What you need to do is to subject the original transformer to study.

If the original windings are pitch or wax coated, place the transformer in a bath of mineral turps for 10 days and dissolve that off.

Document the original winding geometry, the wire diameter and the insulation thicknesses with a micrometer. If any of the windings still have continuity, measure the resistance and inductance on the meters. Find out for the layered windings the turns per layer and the total turns. Patiently unwind it and document everything.

You will be able to recreate the transformer. Even the wave-wound EHT overwind can be done with a simple wave winding machine. And if the core is damaged,likely you will be able to find a replacement core from a similar, perhaps not identical transformer on ebay.

When you have re-wound it, I find that a very good insulation varnish for these transformers is Marine grade Spar varnish, or most transformer varnishes work. The trick is to dip in multiple times in the varnish to build up a thick layer over the overwind surface.

If you need to replace the winding that powers the EHT rectifier heater, you can take the central core out of 27kv rated EHT capable of a modern defunct EHT transformer from a modern transistor TV set (these are all over ebay) and the central core is good for 17kV at least.

Recently I subjected a vintage TV's LOPTY to study (A Bush TV22), this was in a case where there was not a donor transformer to unwind, but a very large amount of detail was acquired from the set, including the winding resistances, winding turns numbers, winding inductances, leakage inductances and winding resonant frequencies and coupling coefficients and winding self capacitances. Here is the article which may be of some interest as it explains how many of the properties of a horizontal output transformer can be deduced by measurements & calculations:

http://worldphaco.com/uploads/BUSH_TV22.pdf


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