Heathkit IB-1100 frequency counter teardown + repair. Contains nixie tubes!

[SingedFingers]

I recently acquired a Heathkit LED based counter (IM-2410). Accidentally I noticed an IB-1100 appear as well just afterwards in the "you might also be interested in" section as spares/repair untested. Bids placed and it finished at a miserably small £16. So it was mine. Arrived this morning. I can't resist old things that are broken.

Quick inspection showed the plug had dissolved and the pins were sticking out at all sorts of funny angles which is sort of expected for the age and the mains cable was one of those very dodgy flat ones popular in the late 1960s and early 1970s, so it got the snip instantly.

Cracked it open and it was quite tidy. No explosions, leaked capacitors and only one dead thing to be removed.



Did a few checks for shorts and checked the ESR of the large electrolytic capacitors in circuit and all is surprisingly good. I removed the mains lead entirely and replaced with an IEC lead I had lying around. This is going to have a plastic strain relief grommet added for reference; I will order one later.



Thought wire and fire bitches, plugged it in and got a pleasant surprised. All zeroes:



Dug out the crystal tester I made from EMRFD and plugged it in with a 7030KHz xtal and it's counting properly:



In the interest of keeping it alive and not risking anything, I am ordering replacement electrolytic capacitors for the whole thing, will strip and clean it and add a strain relief grommet and test all the nixie segments but it's working pretty well.

IC date codes latest are 1972 so it's at most 45 years old. Good job Heathkit; this is why I buy their stuff!