Cardmatic update & ?

[Henry Kolesnik]

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

 

[Chris Haedt]

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

 

[Henry Kolesnik]

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

 

[Chuck Harris]

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.

Don't! At best, it won't work, at worst, it will explode. The mercury
cell is a one way reaction. It cannot be reversed.

Been there, tried that, blew it up!

-Chuck Harris

 

[Henry Kolesnik]

It's fixed, a new day respite helps. Previously I noticed that the
component board had been removed at some time becasue I could see signs of
resoldered wires on the non-component side. (At that time I found a cold
solder joint on R231.) I thought perhaps a wire had come off or someone
transposed some. Being lazy I got the high intensity light out and thought
I could see if there was a problem without taking the board out, there's
only 4 screws! But before doing that I thought I'd recheck the 10K ohm Gm
bridge resistors, pot and as I was connecting my Fluke to the10K resistor
lead I could see it was wrapped around the post but not soldered, same for
all of them. Eureka and happiness, good light helps. I took a pix and posted
it at alt.binaries.pictures.radio. I soldered 4 ends and now it works like
a champ and checks a known good 12AX7 as good. No more meter slamming
backwards on Card 9 or power kick off and the Lo Gm pot works per spec.
After more careful inspection I could see where others have tried to repair
this one because I could see other signs of soldering and component
replacements, some not so good. Since it was like this from the factory,
it had to have been continually intermittent and became a waster of gravity.
Anyway I'll be it didn't get much use and I think the condition of the
switch matrix with all the waxy stuff was becasue it was sprayed trying to
solve the no solder problem. This one is Serial No. 703 so if you have one
near that you might want to check R 402, 403, 404, and 406 for no solder!
73
hank wd5jfr

 

[Jeffrey D Angus]

It's fixed, a new day respite helps.

Which just undescores what I've been telling my techs all
along. VERIFY everything before you start flogging the
assembly.

Jeff

 

[Henry Kolesnik]

In this case the "assembler" needed flogging!

hank wd5jfr

 

[Lou deGonzague]

This was a very interesting post Henry, I have one of these and it seems to
be working OK. I have everything except the cal cell is dead. I would like
to see a pic of those jam nuts that you shouldn't touch if possible as I
thought about cleaning the card reader.

 

[Alan Douglas]

Hi,
The calibration cell simply verifies that the meter is 100
microamps and a total of 250 ohms. And it contains the limit resistors
for the leakage test. I wouldn't worry about it.

Incidentally I wouldn't use any silicone lubricants on the
card-reader pins. While the original organic grease has stiffened with
time and needed to be replaced, it was probably carefully selected to
do its job. On the Cardmatics I've repaired, I've used a grease
originally supplied to General Radio by Oak, but I have no idea where
to get more of it. It was described to me by the GR engineer who gave
me some, as "Beacon M325" grease.

73, Alan

 

[Henry Kolesnik]

For noisy TV tuners back in the 1960s when I was working in a Radio and TV
shop we used Lubriplate white grease that came in a small black and grey
tube that resembled travel toothpaste.We sprayed the wafer switch in the
tuner, rotated several times and then applied a light coating of Lubrplate
with a small stick and rotated several more times. On turret tuners we
cleaned the pads and wipers with contact cleaner on a Qtip and then applied
Lubriplate. This was in Norman, Okla where the humidity played havoc with
tuners making them intermittent and after the treatment we never had call
backs. Somewhere I have a partial tube of this stuff but haven't located it
as yet, so I used DeOxit on the Hickok switch matirix but would have used
Lubriplate if I found it. After about more than 20 moves there's lots of
possiblities where it is. Two local auto parts stores didn't have anything
but silicone grease which I haven't used except as a heat transfer aid on
power transistor heart sinks. I think that Lubriplate would be a good
lubricant/protector unless there's something better that I don't know about.
I'm guessing that there's something better after 40 yeats and would be
interested in what users have used>
Now to repair number 2!
73
hank wd5jfr

 

[Jim Adney]

But before doing that I thought I'd recheck the 10K ohm Gm
bridge resistors, pot and as I was connecting my Fluke to the10K resistor
lead I could see it was wrapped around the post but not soldered, same for
all of them.

Very nice going, but I'm not able to see your photos (server doesn't
have that newsgroup) so could you describe for the rest of us what
this connection looked like?

thanks,

-

 

[Henry Kolesnik]

Lou
Under the black cover over the matrix swtich there are 3 black bakelite
slabs (3.5" X 4.5" X ~1/4") with 187 holes sandwiching 185 pins. With the
black cover removed (2 screws) and the card plunger pushed in and you'll
see that the sandwich "floats" on four 8-32 threaded posts. Each of these
posts has 2 nuts sandwiching the slab sandwich. The position of the lower
4 nuts (I called these jam nuts) determines how far in the 185 pins go into
their female counterpart where there is no hole in the card. If there's a
hole in the card the pins must not make contact with their female
counterpart, and this clearance is about the thickness of a dime. In
addtion all these jam nuts must be on the same plane so that the sandwich
is orthagonal and will not bind so it can move smoothly.
A pix would have been easier but the batteries are being charged. Let me
know if you still need a pix.
73
hank wd5jfr

 

[Lou deGonzague]

Thanks Henry, I see what you are saying. The pins come up to about an 1/8'
from the top of the plate. One thing I just noticed, there is no pin in the
17A position, bottom left corner spot. I wonder if mine is missing or it
was made that way?

 

[Henry Kolesnik]

There's 187 holes with 185 contact pins. A17 has a threaded guide post that
sets the gap (about a dime) between the two female connectors that the pins
connect when there's no hole in the card. H17 doesn't have a pin nor does
it have the lower female solder connection, I guess they didn't need it.
Perhaps when someone has or will find a need for the 186th pin we'll have to
find an extra pin and a lower female contact and a place to route and
terminate the wires.
73
hank wd5jfr

 

[Jim Adney]

Very nice going, but I'm not able to see your photos (server doesn't
have that newsgroup) so could you describe for the rest of us what
this connection looked like?

Thanks to those who sent photos. Those "posts" are more commonly
called "turrets", I believe.

Finding these missed solder joints must have given you a VERY well
deserved good feeling. Congratulations.

-