Teardown and restauration of a Citizen CQT-101-C Quartz Tester

[BreakingOhmsLaw]

As promised in TEA, here is a teardown and restore of a Citizen CQT-101 Quartz tester.
https://www.eevblog.com/forum/testgear/test-equipment-anonymous-(tea)-group-therapy-thread/msg3056850/#msg3056850

Inside:





It is very dirty and does not work well. The measurement jumps a lot.
First, i'll clean the thing. To get the grime off, I use an industrial grade alkaline cleaner called TG-20. The stuff works like a charm. Spray it on, wait 10 seconds, wipe clear.




I removed all boards and started testing the caps. They are all quality stuff by Nippon Chemicon, but nevertheless. One 1000uF on the power supply is dry as a dead dingos reproductive organ.
Reason enough to doubt them all. I am going to recap the entire unit. The dead power suply cap probably caused the jumping measurements. I could not be bothered to measure the ripple though.
I did check the OCXO, which came in at 4.319.899 Hz. That said, i did not run the counter on my rubidium source as it was not properly warmed up. The internal clock is about 3ppm off, so the CQTs OCXO needs to be adjusted later. Not going to tocuh it until the new caps get in.

Here's the money shot - OCXO gutted





to be continued