W5M blowing fuses

The beet thing to do is to slowly variac them to 80v, test and sell the good ones as tested working,needing a recap, sell the others asis for parts
That's barely adequate assurance for the power transformer, and it still doesn't address the reliability issues or the OPT. At 80v, I really can't say the amp "tested working, needing a recap". Who knows what will happen under load? It's also more time and effort than I want to spend.

An "untested, for parts" W5M sold on ebay the other day for $355, plus $50 shipping because it had all original iron. I think that was quite a risky purchase but promising for my five. Another W5M with a replaced power transformer has been sitting on ebay for $129...no action. People want their amps to look "all original".

Seems like some owners are technical enough to change a power transformer, but not technical enough to add extra protection to avoid the transformer failing in the first place.
Two transformers. Both the Mains and Output Transformers have issues.
Honestly, I haven't done the proper research to see exactly what the problems are. I don't know if it's even possible to add extra protection or if the transformers are inherently failure prone. Heathkit knew something was up because they changed the OPT to another Peerless model later on during production. Looks like the later models added a delay circuit as well.

When I realized I was looking at a potential "money pit" I took the easy path and bought something I could trust. I don't mind fixing something, but "lemons" are not my thing. Too many of these amps are showing up on ebay for a reason.
 
Time and technology has helped valve amps in some areas, however those with vintage amps that want to retain everything exactly as it was (apart from relaxing their morals for a recap) are leaving themselves open to a higher risk of PT and OPT failure.

The most basic additional protection used nowadays to minimise PT and OPT damage is:
- adding ss diodes in series with each rectifier valve anode.
- adding a properly sized fuse in the B+ CT.
- using a properly sized modern fuse for the mains.

Fuses aren't what they used to be in the 1950's, and they can be diy sized and selected for best protection with a small amount of technical nous, and they don't have to be chassis mounted (ie. they can be added as a wired part and hence hidden from view without resorting to a drill to fit). A secondary side fuse offers much better over-current protection to the PT and OPT from typical part failures seen over decades of operation.

Modern ss diodes shine when they come to the rescue of valve diodes that over the years will naturally go gassy (and stress the PT).

But I guess the hurdles to jump are the technical diy aspect of adding those parts, and the reticence that resale value will somehow drop (which doesn't really sound logical if the outcome is the cost of a new transformer, which may not be original).

And given this thread seems to include after-market mods which deploy ss diodes, then some caution is needed that the ss diodes are adequately sized for the application - and that pretty much means in voltage rating by using multiple series 1kV parts, and not with using 3A monsters.

Ciao, Tim
 
Mine W5M had 16309 output Tap, in near mint condition with service manual.
I recapped then 1 year ago, and replaced coupling caps with 1 uf X 630V.
Last night, i was listening it with my scott 121-C in a mono system
One hour of music, and the fuses blew without visible reason.
The TAPs isn't too hot.
I removed all tubes, and with DBT, the amp show short signal, like bulb shinning more and less.
a great sadness.
Now, i have to found if the problem is in power tap or output tap, or both.
The problem will be... find a replacement TAPs here in Brazil.... Almost impossible....
Regards
 
Havols, your efforts to only replace coupling and electrolytic caps appears to be quite common.

If you added protective parts at the time of replacing the caps then your amp would likely still be playing today, as transformer failures are imho mainly caused by other parts failing first (especially valves).
 
Is it being suggested the power transformers run very warm to hot because of failing rectifer tubes or today's higher AC mains voltages?
 
Well I had a few moments yesterday so I gave Heyboer a call.

I was told the 110/115 voltage designs are prone to over heating because of the over voltage, and the old insulation's properties easily fail when overheated.

New transformers designed for today's more typical 120/125 voltages, with better insulation and more efficient steel laminations seem to be the best way to go to turn these into daily drivers.

I know bucking transformers would deal with the high supply voltages but since I am not personally concerned with historical cosmetics, already one has a original that was protected by the bimetallic turnon protector, the other a Heath supplied Stancor replacement, two originals would become available to someone who is concerned.

Now just need to make the time to get the replacements and get them installed.
 
Havols, your efforts to only replace coupling and electrolytic caps appears to be quite common.

If you added protective parts at the time of replacing the caps then your amp would likely still be playing today, as transformer failures are imho mainly caused by other parts failing first (especially valves).
right trobbins.
unfortunately, i just replaced the caps, and some resistors. I don't add the diodes on rectifier tube.
My original plan was use 2 W5M power amp with a stereo SP2 preamp heath kit.
But now, I'm thinking to sell this W5M "as is". The output transformer is 16309. I think this transformer is also unreliable.
I have a W3M here too. Maybe my efforts are going for then now

Thanks for reply
 
Is it being suggested the power transformers run very warm to hot because of failing rectifer tubes or today's higher AC mains voltages?
I always used a buck transformer. So, voltage on the wall is around 116VAC.
Regards.
 
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