Hi, I recently took up electronics as hobby and I am still a beginner. Someone gave me an old LCD screen that was not working. I discharged the killer capacitor. I started taking some components out of circuit and testing them. I came across two diodes. When I measured the one, an SR5150, in diode mode it gave me a reading of 0.00000 but didn't produce a tone; reverse it reads OL as expected. I put it aside . I then measured the next diode, a SR506, and it again gave me a reading of 0.00000 but produce a tone; reverse it reads OL as expected. I thought these readings were odd and so I went into my parts bin and took out an new SB560 I bought from RS a year ago and measured it, and i got 0.00000 with a tone; reverse it reads OL as expected. I am very suspicious about the forward readings.
Anyway, then thought if I apply a voltage across the diode i can measure the Voltage drop in the forward direction. I hooked up the SB560 diode to the 12V rail of an old PC power supply I use as a bench supply. Almost immediately as I connected the diode, the led on the PSU went really dim and some smoke came out the crocodile clip on the negative lead of the diode and the cable to the clip extremely hot. I very quickly disconnected the crocodile clip. The light on the PSU came back on.
Anyway, then thought if I apply a voltage across the diode i can measure the Voltage drop in the forward direction. I hooked up the SB560 diode to the 12V rail of an old PC power supply I use as a bench supply. Almost immediately as I connected the diode, the led on the PSU went really dim and some smoke came out the crocodile clip on the negative lead of the diode and the cable to the clip extremely hot. I very quickly disconnected the crocodile clip. The light on the PSU came back on.
- With much smaller diodes the multi-meter reads Vf just fine. Is the issue above a short coming of the multi-meter or do I maybe need a new battery?
- If i connect a diode to a power source without any other circuitry will it just try to pull as much current as it can or did I maybe connect it incorrectly?