$7 Smart Component Tester (LCR-T4 M328)

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Would that unit be able to diagnose a digital clock? I have a clock that came out of an old Marlboro advertising sign from a Circle K store in the mid 80`s that I set in a brass housing. It worked for years and years and one day started blinking like the power had shut down. Took it to a guy I know that fixes electronics and he had it for a couple months and it didn`t malfunction. I brought it home and found a loose connection in the cord which I repaired and it worked fine for a couple more months and the same thing. I can plug it in and it will run for a while and back to the same old, same old. I want to repair it because it`s the only clock I found that I can see at night with my glasses off, lol. Unless I spend big money on a new one.

No, it will test components that are removed from the circuit. Sounds like it is a power supply problem. I'm guessing this clock uses 5VDC logic. You can either figure out what is wrong with the supply, or replace it with a AC mains to low volt supply brick. Does the printed wiring board have any silk screen legends that indicate voltage? I don't know what your electronic skills are.

They do make a model of this, that has a boost supply that can test Zener diodes to 30v. This is what I purchased last year off eBay (search for "LCR TC1", you can find a USA seller if desired).