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If you deal with electronics for work or hobby, this is something to have! They are cheap $6-$7, but come with no instructions.
https://www.youtube.com/watch?v=svis...ature=youtu.be
Got one of those smart component testers: resistors, capacitors, transistors, MOSFETs, diodes, ... Testing the tester.
WARNING: There is always a danger of shock, fire and electrocution when working with electricity. Capacitors of high voltage can kill if mishandled.
I have to get one of those! I have a huge stockpile of components salvaged from old equipment and passed to me by folks retiring from the hobby. Identifying and testing it to select what I need is an eye-watering task.
I don't like to deal with Ebay or Bangood and the other Chinese-direct shippers but I see that the unit is available from Amazon...
https://www.amazon.com/Multifunction...J6JE19EAC96R9G
for $ 15.50 so it's on my shopping list.
FYI: There is another style that has a digital selector. This one in this video is faster and easier. The selector type has calibration (and a basic freq gen, and freq counter). Either and both are better than doing lookups or using scopes, freq gens and standard parts to find values.
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.Quote:
Originally Posted by mklotz
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.Quote:
Originally Posted by baja
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).
Yeah, I remember from prior experience about removing the components to test them. I have minimum-t0-moderate electronic skills. There is no legend on it indicating voltage but I can remove it from the circuit and test the voltage and see what it is. The circuit board indicates it`s made in Hong Kong and has "0" jewels, lol. Thanks!Quote:
Originally Posted by metric_taper
Posting a photo would be helpful to see what the power supply (an analog circuit) and the digital clock circuits look like. I'm guessing it uses one IC that has the time clock, and the LED drivers. Can't help without seeing it.Quote:
Originally Posted by baja
Attachment 32683
Got a bit sidetracked by Christmas (Merry Christmas to all!) but finally got a pic done. I agree about the power supply being the problem since when it malfunctions, it acts as if the power went out and came back on.
Well the component side of the board is facing away. Easy to see a transformer connected to the mains, with 3 wires. This has the white wire as a center tap of the secondary, so they are doing a full wave rectification. I can see on the PWB silkscreen where the three wires go through, one is labeled CT for centertap, and this looks to also be the ground reference connection as the circuit trace wraps around the board. I don't see any cold solder joints, but that may be the camera resolution or hidden by munge.
I would look for a loose connection as the photo shows it's working now. Check out all the solder joints. You could touch the ones up in the power supply area of the board around where those low volt power wires are going through. Can you pull the board back to see the other side better. Look for any damaged capacitor, or lead that is broken. There must be 2 diode at least from the blue wires to a positive connection, I'm guessing they are using a fixed regulator, that would be a 3 terminal part, this would take the rectified voltage from ~8-12VDC down to +5VDC.
When it flashes, does it loose the time setting? If so, then I'm guessing the main power is the problem, if not, then it might be the supply return wire between the boards.
Start by inspecting all solder connections on each assembly and carefully look at connections between the assemblies.
Good luck.
Many thanks, Metric Taper. I`ll dink around with it and see what happens.Quote:
Originally Posted by metric_taper
My tester arrived from Amazon a few days ago. Assembly was straightforward though one end of the plastic case won't fit without putting a lot of stress on the display cable. I solved that problem by not installing that part; doesn't affect performance and provides better ventilation of the electronics, though they certainly don't need it.
If you're an electronics dabbler this thing is just downright KEWL.
I pulled what I thought was a 100 pf cap out of my collection, plugged it in, and discovered it was a mini inductor. I have a lot of reclaimed components and this sort of misclassification is bound to happen but the tester will set me straight.
It produced believable values on a host of other components I tried. I had a few precision resistors so was able to test accuracy a bit and it was spot on on those.
I love it.
