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Peerless 16039 output transformer needed for Heathkit W-5M

tutor turtle

tutor turtle

New Member
I took a pair of these mono-blocks in for recapping/restoration. The good news is, I found out the incredible cult following these amplifiers have, which implies the customer is less likely balk at the bill. The bad news is after doing all the work of replacing the caps and resistors, one of the Peerless 16039 output transformers has an open winding :(. Come to find out, these output transformers are the Achilles heel of the beast. Orphaned amplifiers being the only source of replacement output transformers. Doing a little research I found Heath changed the the part in late 1958 to Peerless 16458, more reliable, but somewhat different sounding part. The 16309 has a nickle core, the 16458 is all iron. A contributor on DYI audio blog claimed a Peerless S265Q was an electrical match, though in a bit lager package. 100K ohm input impedance.
Any advise along the lines of suitable replacements would be welcome.
 
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If its open where the leads connect to the winding, you may be able to reconnect it, if you can open the case...
 
Looks like rewinds are in the $200-$300 range. Ironic timing as the customer just called as I was looking it up. He asked me to put it aside so he can think on it, which translates to mean I'm unlikely get paid for work done. I think I'll try John suggestion, I have had some luck reattaching broken leads, burned winding's are another story.
 
knockbill said:
If its open where the leads connect to the winding, you may be able to reconnect it, if you can open the case...
Click to expand...
Someone on the DYI blog said he put one in the oven, on a moist cloth, set at 230 for two hours.. It became soft enough to ease it out of the case. He then froze it and chipped away at the tar to expose the bond points. What have I got to lose?
 
tutor turtle said:
I pinged the seller if he would sell singles, he will. I bought what I needed plus a spare.

Thank you so much for your lead..
Click to expand...

That is awesome! I posted that link while in smart ass mode and am glad you turned it into something useful. Despite the 16309 being a weak link, the amp actually sounds really good with it. There is another weak link on the W5-Ms however, the power transformer. It was bad enough that Heath published a service bulletin recommending that it be replaced with a Stancor PC-8412 (400-0-400, 200mA). Although not inexpensive, there are modern equivalents that are easily available should your customer ever pop one.
 
Failure of PT's and OT's should generally be preventable by adding protection that is considered quite normal nowadays, and easily sits in with replacement of old electrolytics and coupling caps as part of a typical restoration effort. Perhaps the easiest protection starts with the PT, and in particular with adding series SS diodes to each rectifier anode, and adding an appropriate fuse in the CT. Most part failures that cause over-current in the PT, and OT, are then not likely to cause collateral damage.

The W5M has 455VAC secondaries, so at least two series 1N4007 added in series with each 5R4GY anode is a very simple protection enhancement.

Adding a CT fuse is not so easy, but well worth it. A PSUD2 assessment would identify both the hot turn-on and the continuous rms currents passing through the fuse, and the fuse design chart can identify a suitable fuse specification, and value, to provide good protection. The selection process is a little technical, and a guide is provided in the link below - with a bit of time that selection could be done here using an agreed PSUD2 circuit.
http://dalmura.com.au/projects/Valve amp fusing.pdf
 
Heath overstressed the OPTs making impressive output specs, derating the amp by redesigning the ps to lower B+ to more reasonable levels is part of a good resto. There should be at least one good thread on derating these amps.
 
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