Chris
I am guilty of not heeding your advice on the jam nut but it was not
intentional mistake, it was the result of several attempts to get the parts
back together. But a dope slap imigh tbe in order. I'm very impressed with
engineering, design, and manufacture of the switch. Except for alignment, I
don't see any need for improvements. I'd guess the facctory had a jig for
aligment. I used a 13/64" allen wrench as a "feeler guage" after I
determined what clearance was necessary to make sure all pins were out and
how much they needed to go down so the female contacts would snap in the
grooves of the pins. It took hours but the next time it will be quicker!
As far as the 54 test cards, I can't get proper readings on 1 thru 5 as
my Cal. Cell is dead, or Card 9 but the rest are in spec! For the
calibration cell Alan Douglas's book shows a 4.7 volt Zener while the
USM-118 website has a 5.1 volt Zener and I'm trying to find out if the
difference is important.. I think I may attempt to recharge the Cal. Cell
mercury battery with my constant current source and see what happens.
The tube socket voltage and resistance readings pretty much agree with
the data in the manual. All the electrolytics pass on my Dick Smith ESR
meter.. I'm a rifleman not a shotgunner when it come to caps unless there
is evidence that most of the caps are suxpect because of manufacturer or
age. Besides, I like to know what component caused the fault. Next I
think I'll let the unit hot soak for 24 hours and look at it with a scope.
It passes the breaker tests fine so I don't think relay needs
adjustment. Since the Card 9 problem is not always repeatable it's difficult
to pinpoint. What happens on Card 9 is sometimes the meter tries to go
below zero and sometimes it kicks the unit off. I'm still trying to figure
out how this Gm balance bridge circuit works. I've colored a set of
schematics with Card 9 switches activiated and trying to get thru the maze
to see if I can pinpoint the fault.
All that being said the Cardmatic is one hell of a design for a tube
checker! I've got to get it going because I hve hundreds of tubes to check!
Any all tips appreciated.
73
hank wd5jfr

"Chris Haedt" wrote in message
om...
"Henry Kolesnik" wrote in message
...
I've got one of my Hickok LS 15874 L2 Cardmatics going. I cleaned,
lubed
and realigned the switch matrix as well as other switches and also found
a
cold solder joint from a previous repair. About 100 of the switch matrix
pins had what looked like old paper capacitor wax on them, very sticky!
I
took all the pins out, cleaned each one and the sockets. (An ultrasonic
cleaner would have been nice.) It took several attempts to get the
clearance correct, since the jam nut moved but I finally figured out a
system. Now it appears to test tubes just fine but it still has one
problem
that escapes me and wonder if anyone would have any ideas. It responds
per
the manual to all test cards except card 9, Gm, Low Ib. About half the
time
card 9 will kick power off and I'm guessing it's because the meter
kicks
backwards below zero when button 2 is pressed When it doesn't I can
adjust
Low Ib per the manual and seems to work fine. However sometimes the
meter
needle doesn't go below zero enough to kick the power out but when this
happens the Ib control has no effect! Any ides or tips appreciated.

73
hank wd5jfr

I told you if you moved those jam nuts at the bottom of the reader
you'd have fun! Have you replaced ALL of the electrolytic caps? Caps
could be the cause of what you are seeing. Plus--seems like there is
also an adjustment for the sensitivity of the circuit breaker in the
machine. There are something like 50+ cards to calibrate the
machine--went through all of those?

Chris