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Heathkit W5m Power Transformer?
Heathkit W5m Power Transformer?
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Old 1st August 2019, 01:13 AM   #1
maniac303 is offline maniac303  Canada
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Default Heathkit W5m Power Transformer?

Hello,

I am rebuilding a pair of W5m and one has a short in the power transformer HV secondary. I have a few related questions;

1. Do any of you kind souls have a working power transformer for a W5m? (Heathkit part number 54-32) There are none on EBay at the moment.

2. The transformers have two numbers on them, both labelled 54-32, but one is labelled 138626 and the other 1386304 with STANCOR ELECTRONICS INC. on it as well. I know other manufacturers made TFs for this unit, but if I search these other two numbers the TFs that I find don't seem like a match. This may not be important but does anyone _know_ what these second numbers designate? Cheers.

3. The chassis are in pretty rough shape. I am considering stripping, blasting, repainting and relabeling. Does anyone know a good DIY source for hi-rez silk screens made from computer art? Feel free to lecture about resale value and all that, but I mean they are in _really_ bad shape, one is badly bent. I am rebuilding the non-functional amps with the intention to use them, not intending to sell.

TIA
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Old 1st August 2019, 06:47 AM   #2
indianajo is offline indianajo  United States
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Getting a matching OEM transformer for a decades old product is like searching for the holy grail. You might find one in a similar unit, but then it might be easier to rebuild the dead unit you buy. Heathkit amps for parts or repair on e-bay tend to be pricey. If that is a vacuum tube amp that makes the purchase price even more improbable. This junk amp market may be moving to facebook, which will be invisible to me since I don't give out my birthdate to any publisher for free.
One can calculate the current demand at what voltages to determine what generic replacement transformer will work. Current use is in tube datasheet. Output transistor design currents tend to be in the SOA table @ what working voltage. The current limit in transistor tables is a rediculous number telling you only how big the bond wire is. If the transistors are house brand, go by what top end output transistor was popular in the year the amp was made.
Guitar amp shops are good sources of replacment transformers. In the US I can think of tubesandmore.com and triodelectronics.com I am sure you have as good suppliers in Canada without paying the stupid UPS/FedEx loan origination fee (~$20) for the customs fee. Hammond Industries is one brand that comes to mind. The stancor factory was redeveloped as a shopping mall or something. All the old US transformer brands are now built in the land of all manufacturing - and all counterfeiting, too.
I find the best bargains in amp hulks to be Peavey. They are reviled for some reason, I got a good PV-4c hulk for $20 with freight. $80 parts to reactivate. Two 65 VCT @ 4 A transformers, one for each channel. Crown & QSC for parts or repair are a little more pricey. Most other brands had figment of the imagination power ratings anyway.
Silk screen shops tend to be local, it is a low tech process much like photography. Ask around small run print shops. The same screen that works on T-shirts would work on a front panel.
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Last edited by indianajo; 1st August 2019 at 06:57 AM.
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Old 1st August 2019, 05:56 PM   #3
maniac303 is offline maniac303  Canada
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Default Heathkit W5M Power Transformer?

indianjo,

The amps are circa 1951, Williamson based, running a 5R4GY, 2 x 12AU7 and 2 x KT66. I am planning to keep the iron (and nickel in the case of the Peerless 16309 OTs) and replace almost everything else. My affinity is for the elegance and simplicity of the amplifier circuit rather than the antique black beauty caps etc. The Heathkit build manual has a great description of the amp, and is a good read:

http://www.mcmlv.org/Archive/HiFi/HeathkitW5M.pdf

Given that the iron is about all I plan to keep I think I will try to be patient sourcing an original replacement. They do come up on eBay from time to time. At the same time they are known to fail, potentially a product of aging caps, higher line voltages and other issues. Heathkit actually advocated a mod, a 'surgistor', to address the issue, and I plan a number of minor changes in this regard as well. The failure rate of the PT may explain the high ratio of Chokes:PT on eBay. Several chokes available, no transformers.

The PT has somewhat unusual specs, 910V w/CT @ 140ma, 6.3 w/CT and 5. I have yet to find an exact, or even suitable match in the aftermarket, and I would prefer that both amps have matching power supplies. If all else fails I may be re-potting and repairing, a learning experience to be sure!

Thanks for your reply!
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Old 1st August 2019, 06:17 PM   #4
rayma is offline rayma  United States
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Lot Of 10 Transformers From Vintage The Fisher & Magnavox Stereos | eBay
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Old 1st August 2019, 10:38 PM   #5
maniac303 is offline maniac303  Canada
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Default Heathkit W5M Power Transformer?

Yes, this is an example of one of the few hits I get if I search for "1386304", but I have no idea if that is a vendor ID, manufacturing date code, or what it means exactly. The other number on that particular transformer on eBay, 300215-2 , has so far told me nothing.
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Old 3rd August 2019, 01:01 AM   #7
trobbins is online now trobbins  Australia
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You may find some snippets of information in the following 2 threads (as well as a lot of the opposite):
Heathkit W5M restorations and mods ideas | Audiokarma Home Audio Stereo Discussion Forums
Mystery Device found in Heathkit W4-AM | Audiokarma Home Audio Stereo Discussion Forums

Heathkit did use multiple transformer makers, but even some of those makers were just related divisions in a changing landscape of transformer manufacturing facilities over the decade or so of interest. The W5M started sales circa 1955, and appears to have still been part of Heatkit's adverts and warranty repairs in to the mid 1960's. There were lots and lots of these kits sold, and hence they are seen on ebay, and some have got them custom made as a repair, or looked around in detail for the closest commercial match. The many examples of them failing may just be equivalent to the many many units originally sold, but like any vintage gear I'd highly recommend adding some extra protection to alleviate the chance of the power transformer being collateral damage to something else failing, even it it takes away from the aesthetic 'original' condition.
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