"EADGBE" wrote in message
oups.com...
On Sep 28, 12:58 am, "Paul Stamler" wrote:

If you're not getting 3.5VAC from the winding there are a couple of
possibilities. First is a fuse -- is there one between the transformer
and
the diode bridge? If so, look for a blown one. If you find one, figure
out
why it blew before replacing it -- possibilities include a shorted
capacitor.

If no fuse, then your transformer's winding may have burnt out -- but
usually you can smell that.

Try detaching the transformer winding from the board, if that's doable,
and
see if the voltage is still missing.

PAUL:

It's pretty much a direct path from the transformer to the flourescent
display. They don't go to a diode bridge because they are never
converted to DC voltage. The two 3.5v leads are soldered to the power
supply board, where each of them runs into a 1-watt "r-fuse". (Both
of the 3.5v leads have their own "r-fuse".) Then these lines go to a
connector near the back of the deck that's mounted on the deck's logic
board. That connector then has straight circuit board lines to a
connector at the front of the deck which attaches to the flourescent
display.

I am measuring voltage directly at the ends of the two 3.5vAC leads
coming out of the transformer. No output at all.


Based on that, I would have to say that the 3.5v winding is open, but by the
same token, I would also have to say that it is extremely unusual for a
single secondary winding - particularly one that has to do little 'work'
like this one - to fail without there being some kind of fault like a dead
short on the end of it. If the windings come out to tags on the tranny, it
would be worth checking that the soldering between the winding wire and the
tag itself is good. I have known the laquer coating of the wire to never
have been stripped properly, which has led to a bad joint at the tag which
has managed to 'make' ok for years, before finally giving up. Also check
that the winding wire has not fractured right at the tag. I have seen that
as well, presumably caused by heat expansion and contraction over the years,
working to break the wire.

As a final check, you could sub the supply. It doesn't have to be AC. You
could just hook up a couple of 1.5v dry cells to give you 3v, and hang that
across the two wires going back to the tranny, having first disconnected
them, of course. The reason I say connect it there, is so that any bias
supply that the filament supply is floated on, still gets applied.

Arfa