On Monday, April 8, 2019 at 4:22:12 PM UTC-4, wrote:
I have 4 of these that we still use here in the house. Last year we
were operating on generator power after a storm, The generator started
surging as it began to run out of gas and I later learned that three
VCR's power supplies were wiped out I'm guessing from this. Luckily I
had three junkers that were kind enough to donate power supplies and
since the power supplies are separate plug in modules I was able to
restore the three machines relatively easily.

The other day we had a 10 second blackout with surging during
restoration. After power came back on I noticed that one of my
machines was again dead. I have the service manual however this power
supply is a nightmare to get into whats more take apart and try to
troubleshoot. I never had to deal with this after the first blackout
when I just did organ transplants. The chassis is soldered together
and the two boards connected with jumpers and then the entire mess was
soldered together afterwards. For a commercial machine from a service
stand point this is a **** poor design.It's not something I'm looking
to rip apart.

I was really hoping that perhaps someone who worked on these units
back in the day may remember power surges causing any particular
problems with these power supplies. That way maybe I can squeeze in
there and get at just what I need to without having to remove a bunch
of stuff in order to get to it.

So now I have 4 bad power supplies that actually may all have the
same problem and I'm not sure what I'm going to do. If anyone can
please help me with this I would sincerely appreciate it. Thanks,
Lenny

They used to offer kits for these. They included the Mosfet/Transistor, driver, ref IC, a bunch of zeners, and all the capacitors in the primary and secondary. It's normally high ESR caps in the primary that wipe these out. As long as they're plugged in and warm they're happy, but if they lose power and go cold, they'll blow the mosfet as soon as power is restored.

Email my brother and see if he has any supplies left for these. I know he got rid of a lot of stuff but you never know. If you find one somewhere, make sure you recap it before plugging it it.