"Henry Kolesnik" wrote in message ...
Hi

Both my Hickok Cardmatics, KS-15874-L2 have been mothballed for about 10
years and both exhibit the same symptoms as well as both Cal. Cells are dead
(I've seen the reverse engineered schematic and wonder if anyone has had
success with repair or an external bypass.) I brought both up on a Variac,
no smoke and both draw a little over a 1/2 amp. Cal. B+ indicates the
meters are OK . For example neither will test a known good 12AX7, the meter
tries to go a little backward on Gm, and the 4 button lamp lights indicating
a dual section tube. Does anything come to mind of where I should start or
am I facing cleaning off the test bench and staring at hours of learning the
circuits for basic troubleshooting each mechanical and electronic section?
I kind of feel that there's a common fault that someone with lots of
experience might point out.

tnx & 73
hank wd5jfr

I do think that you may have a cardreader problem. One thing that
can happen is the whole assembly starts to slow down due to old
hardened grease. This makes for nice smooth operation--but the
machine will not work properly. The reader really needs to slam to
work properly. It has to "fire" the pins into the mating female
contacts. If you have Alan's tube tester book, you can see a picture
of the reader and the pins that need to be cleaned. A tiny amount of
white lithium grease (I used some from GC for wiping contacts) is a
good idea on the tips of the pins. Cleaning the cardreader is not
that easy, and requires loads of patience. Oh--It's easy to take
apart--but getting it all back together can be difficult--especially
the first time you do it. Plan for a day of careful work and then you
won't get upset. Make sure you do NOT adjust the nuts on the studs
supporting the reader plates. Getting all that readjusted properly is
a minor nightmare. If you see that the wiring is disturbed or messed
up going to the bottom of the cardreader, it may not be a practical
thing to repair.

The KS Cardmatic is my favorite tester, and the one I use 95% of the
time. You really need to rebuild the whole thing for it to be
reliable. Unlike other Hickok designs, there are many high voltage
filter caps to replace. It takes me a couple of days+ to redo one of
these machines--but I feel they are well worth the effort.

The calibration cell is used to check the meter in the tester and
calibrate the shorts test function. Original cells used mercury
batteries that have all gone dead now. A new calibration cell can be
constructed using Zener diodes--that is how the later ones were made.

I'd go for some sort of trade arrangement also.