I'm trying to fix a digital multimeter. It was working until I blew the fuse (actually the "buzz" for continuity wasn't working). I've now replaced the fuse but it's acting strangely. When I turn the dial to V, nothing happens. But when I turn to anything else, it makes a continuous, very fast clicking sound - like the piezo buzzer is trying to do something. And at each position of the dial (other than V) there are brief flashes of life on the LCD. It doesn't seem to matter if the probes are connected. I wasn't sure where to start, so I've tested most of the diodes and cleaned the zebra connector on the LCD with alcohol (without removing it). But no change. Any suggestions?
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pictures are a usefull start
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Here are some images.Comment
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check all the transistors for shorts - they may be used as protection devices.
and clean the switch tracks and see if they are burned - i'v seen that before after an over-current situation.
put silicone grease on them afterwards - it prevents arcing.
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"it makes a continuous, very fast clicking sound".................. if is about 3 or 4 times per seconds, that may be represent a refresh rate of reading, and I guess some short maybe, if LCD readings go off simultaneously with clicking... Check whats going on processor supply voltages, is stable, or follow clicking?Comment
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yes, just check resistance between the pins.
do you have a manual?
radio shack stuff often had schematics in the manual
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I have the manual but it doesn't have a schematic and I haven't been able to find one online either.Comment
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I checked the resistance of all the transistors (everything marked Q with 3 pins), but I'm not sure how to interpret the results. Some only had a low resistance (around 6 ohms) between 2 of the pins. A bunch had low resistance between multiple pins, but couldn't that be due to parallel components?Comment
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it could be other components but it still sounds suspect.
a good transistor looks like 2 diodes on a multimeter,
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Dear all,
I have this old radio clock by Sony from the early 80s, I guess. The clock display works, but is dim, the function board appears to be OK - but the radio unit shows no signs of life. It doesn't produce a single noise, crack or anything from either FM or AM band. It's like it doesn't even power up.
i opened the radio and it is full of some TRACON gray capacitors. They only have their negative strip printed, voltage and capacitace markings - no series, no temperature marking, nothing else.
My question is, do you know of this brand of capacitors and how bad are... -
I'm looking for the dial cord winding settings for this radio!
I spend most of a whole day yesterday trying to figure this out. I just need to know how many turns for the tuning knob stylus to get me started, then how many on the lower and upper bobbins on the first cord pulley (there are two on either side of the tuning band area).
The dial cord system has a central gear where the dial cord spring and stay is, then the tuning knob stylus and two small rollers each with a small and a larger bobbin holder. I finally figured out how to wind the cord on those bobbins... -
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2024 BEV, BIH, SARAJEVO START PROJECT: ELECTRIC VEHICLE TOYOTA 4 RUNNER CONVERSION http://www.bev.ba/TOYOTA4RUNNER/index.html
2023 BEV, BIH, SARAJEVO START PROJECT: SECRETS AND MANUFACTURING PLANS (AS MY REPLICA) OF THE LIBERTY ENGINE 2.0.
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2019 BEV, Croatia, Ston:, Broce: PROJECT - PROJEKT ELEKTRIČNI GLISER http://www.bev.ba/ELEKTRICNIVANBRODSKIMOTOR/indexHR.htm...12-28-2023, 02:09 PM -
I recently bought one of these I do I use this device correctly
https://www.ebay.com/itm/406019936826?var=676327747036 -
04-24-2025, 07:54 PM
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