Cubdriver wrote: ↑Tue May 28, 2024 2:43 am
Good to see you at least poke your head up. Fingers crossed that you get a bit of a break to decompress and enjoy yourself a bit. I suppose that feast beats famine where work is involved, but neither can be a permanent condition!
-Pat
I'm on holiday now. It's been nice to not set the alarm clock and sleep in yesterday and today, and spend some time decompressing.
I totally forgot to post a few pictures of repairing that alarm clock. This is what happens when you don't have time to enjoy your workshop and do a total over-the-top geekout on a simple one capacitor repair. About the only thing I didn't do was put an oscilloscope on it to see how bad the DC looked:
That's the internals of the clock exposed including the faulty 200 uF filter capacitor on the left. The main guts of the operation looks like it's an LM8560 chip but I haven't looked it up yet. The ripple voltage is horrible.
Testing the replacement capacitor bridged in across the original which reduced the ripple voltage from close to 3V down to less than 50 mV. I removed the original and permanently installed the replacement and put the clock back together.
I put the original capacitor on the Keysight U1733C out of curiosity to see how bad it was using the 120 Hz test frequency to check it at the ripple frequency it would've been exposed to in-circuit. Most of the capacity is gone and the ESR is horrible.
The Chinese tester whose breakout cable I repaired at the same time couldn't even make sense of it.
What surprised me in this repair is how much quieter the clock's little transformer runs now that it's got a fresh filter capacitor. It was humming loudly with the original one and I didn't notice it as it got louder over the years. Anyways, the tentative plan is to put the dead speaker from the mosque on the bench tomorrow afternoon and sometime while I'm off, the little HP nixie frequency counter.