CapSnap123
Member
Last Activity: 01-01-2025, 03:30 PM
Joined: 04-20-2024
Location: NY, NY
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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? -
I have the manual but it doesn't have a schematic and I haven't been able to find one online either.Leave a comment:
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Is it possible to do so in-circuit with just an analog VOM? This is my only DMM....Leave a comment:
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Here are some images.[ATTACH=JSON]{"data-align":"none","data-size":"thumb","data-attachmentid":3537544}[/ATTACH]...Leave a comment:
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Radio Shack Digital Multimeter Cat # 22-811
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... -
I have no idea what caused this. I just plugged it in one day and it started to smoke.Leave a comment:
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So you mean just cover the windings with, for example, polyurethane from the hardware store? Here's a photo of the windings (on the right)
[ATTACH=JSON]{"data-align":"none","data-size":"full","title":"variac.jpg","data-attachmentid":3498174}[/ATTACH]...Leave a comment:
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Fixing a variac with shorted windings
I have an old "Adjust-a-Volt" variac. Shortly after I bought it, it started smoking and now the windings look burned for about 2 inches around the left side. Is it possible to fix this or bypass the shorted windings? I'm not sure how to detect where the bad windings are, except by appearance. -
I figured it out - it was a bad LED plus the wires on the IR photodiode were reversed (nice self-inflicted injury there). Thanks for all the suggestions.Leave a comment:
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The receiver is a photodiode, not a phototransistor. Is that a problem? I didn't realize there was a difference when I bought the replacement and unfortunately don't have the original component anymore to check what it is - though it looked the same (black LED shaped component).Leave a comment:
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Finally had a chance to get back to this. I tested the transistor, the SCR, and all the caps. One of the caps had a high ESR so I replaced it but it didn't help. I get about 22V across the IR LED and open across the phototransister all the time (do you test it with the ohm-meter?). I've attached a photo of the back of the board.Leave a comment:
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When working properly, with the switch on, the shredder sits quietly until a piece of paper is inserted. But currently it starts shredding as soon as the switch is turned on.
I previously cleared all the dust. I took the relay off the board today and tested it. It works. When the power is on, it completes the circuit and breaks it when the power goes off. I removed and connected the IR photodiode to my multimeter and it gave between 10 and 75mV when I shined a TV remote on it. In the dark it gave about 200mV (the values were very erratic). I looked at the IR LED with my iPhone camera...Leave a comment:
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Sensor on Aurora AS1018CD paper shredder doesn't work
[ATTACH=JSON]{"data-align":"none","data-size":"thumb","data-attachmentid":3256645}[/ATTACH] I'm getting frustrated troubleshooting a paper shredder. The way the shredder normally works is when you turn the power on, nothing happens until you insert a piece of paper. There is an IR shredder in the shredder and inserting the paper breaks the beam and starts the shredder motor. But now the motor runs constantly, even when no paper is inserted. I've replaced the photodiode and the IR emitter. Also the relay makes a nice clicking sound so I assume...
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