17 Jun
2005
17 Jun
'05
12:41 p.m.
----- Original Message -----
From: "Jules Richardson" <julesrichardsonuk at yahoo.co.uk>
To: <cctalk at classiccmp.org>
Sent: Friday, June 17, 2005 12:49 PM
Subject: Re: Monroe electromechanical calculators
I have had some success on Tektronix 'scope switches. I soak the sitch wafer
in de-greaser (I've used the RS aerosol version), changing the solution a
couple of times, then I allow the switch to air dry, before lubricating it
SPARINGLY with contact lubricant, and a suitable grease for the mechanical
detent and bush.
The other thing to check is the filter capacitors on the motor and mains
input - the can be temporarily disconnected for a quick check (but if you
leave them off, the neighbours will complain -TV and radio wiped out for
about 200yds!)
If the governor is similar to the type used on Creed teleprinters, then make
sure that the contacts are properly cleaned and burnished - they have a
tendency to "hook" and make a permanent contact, allowing the motor to
overspeed.
Jim.
> > There's some earth leakage which would
be useful to track down -
> > possibly a break-down in cable insulation? I've not worked out what
the
Most of the time, that's due to tracking across the impregnated fibre
insulators used in things like the automatic on/off swtich.
Aha, well I can isolate and test easy enough there without any severe
dismantling of things. Can anything be done to fix the problem (short of
making new insulators)? > Almost certainly a governor. Do not be tempted to
bypass it, many of
> these machines used series wound motors which will get up to a
ridiculous
speed if not
controlled and do considerable damage.
Yep, I saw somewhere that 180rpm is typical for governed motor speed...