"Phil Allison" wrote in message
...
Arfa Daily wrote:


** Just as I suspected, those NRE toroidals are time bombs.



It's inside a piece of heatshrink sleeve bigger than I've got to replace
it
with, but on the blown out one, you can still read "4R7" so I guess 4.7
ohms
which would be about right. Assuming that they have it done, I suppose I
will have to get a length of suitable heatshrink in so that it's restored
to
the insulation levels that it came out of the factory with.


** The shrink cover is there to retain bits if the PTC explodes and nearby
wiring away when it "trips" - cos its gets so damn hot.

Be far better to slip a piece of silicone tube over the thing, as is often
done with NTCs.


Thinking about it, you're probably right about the reason for the sleeve.
I'm sure I'll find something suitable.



I was able to
just about get my meter across the bridges after the tranny wires had
been
pulled, just to make sure that there were no issues with them or anything
south of them, but all looks ok, so I think that it is just the tranny
primary short circuit for no good reason other than it felt like it ...


** You gotta hope the new one does not get that same feeling, or the other
one in the amp.


Yes, that's what bothers me. I never like high cost repairs to older items
like this. It often seems to be the case that once they start failing, they
just carry on with a different problem each time, just inside the 3 month
warranty ...


For my XLS602, I used a "pre-loved" toroidal tranny that was on hand, with
a similar main secondary winding and added a small 18-0-18 E-core for the
low voltages.

Might be smart to get a quote for a replacement tranny made to suit that
Crown.

We got onto the people who handle Crown here today. They said that they
didn't do spare parts, but they did have a transformer. £100 plus shipping
plus tax. I suppose that's not a lot of money when you consider that it's a
custom four-winding thing the size of a baby's head, but still a lot to
shell out up front for a spare part. Considering the power output and
replacement value of this amp, even if the final repair bill weighs in
around the £200 mark, I suppose it has probably still got to be worth doing.

The customer has been given an estimate now by the shop, so we'll see what
he decides in the next few days, I expect ...

Arfa



... Phil