snip



Just another bit of info for what it is worth.
The DC resistance of the motor windings are
grey to red = 4k49
grey to blue = 4k49
red to blue = 8k99
grey to motor case greater than 20Meg
as read on my oldish dvm
The 220nf cap should be o/c also

Now I am curious as to what you find. If it is the motor, it might be
worth your customer getting the motor upgrade kit if it still available.
http://www.rega.co.uk/html/upgrade_kits.htm
Cheers
DaveD


Thanks for the link Dave. Do you know what the reasoning was behind the
'upgrade' ? Did they have a lot of trouble with motors failing ? I would say
that this is the original motor, coming up on 25 years old. I fitted the 3 x
47k combination, and the motor runs normally. It has plenty enough torque to
shift the heavy glass platter, and according to my strobe disc, the speed is
spot on. Voltage across the motor measured at 98v, which would seem right,
given that the 47k combo comes to 15.6k against the original value of 12k.
In the circumstances, I'm prepared to call 98v on a 110v nominal motor, a
draw.

I s'pose it wouldn't be a bad idea to just check the winding resistances
before it goes back, but I don't think I'll be expecting to find a problem,
as it does run correctly, without anything catching fire.

As to why the original resistor failed, anyone's guess. About 1 1/4 turns of
the spiral element have charred, right in the middle. The resistor looks as
though it has been pretty warm over its lifetime, but again, it is nearly 25
years old, so has worked hard. Could just be that it had started to go high
and suffered a cumulative cascade failure. Might have been a voltage thing.
Some of these resistors, particularly considering its age, are not rated
especially well, working voltage-wise. I suppose that over it's lifetime,
it's had around 130v RMS across it all the time that the motor was running.
Could have been a slight manufacturing defect such as the spiral being
'nicked', that has degraded down the years, to the point where it became a
failure. Endless possibilities ...

Arfa