Hi,
How to find shorted caps with a DMM?
Thanks.
How to find shorted caps with a DMM?
Thanks.
-
-
Re: Shorted caps
You measure the resistance and if it's zero (or small) it's shorted.
If it's high or O/L -AND DOESN'T CHANGE- then it may be open.
Remember a cap is gonna charge/discharge from your meter so it will jump around some. You should see it charge and the resistance will go up probably until is says infinite or O/L or out of range.
Then swap leads.
Should do the same thing.
(You should see a discharge then a charge up to the high resistance again.)
Use the 2k ohm scale.
20k works but it will take longer.
.Mann-Made Global Warming.
- We should be more concerned about the Intellectual Climate.
-
Be who you are and say what you feel, because those who mind don't matter and those who matter don't mind.
- Dr Seuss
-
You can teach a man to fish and feed him for life, but if he can't handle sushi you must also teach him to cook.
-
-
Re: Shorted caps
yeah it should be have like a piece of wire basically 0 ohms or near 0 ohms
good caps it wll be like a broken wire, open circuit (DC wise)
(except in the case of leakage not sure how well that shows on DMM's Iam sort of use to old analogs with caps)
Some better meters Do have cap range and if memory serves it will use low level AC @ frequency to measure the caps capacitance
using the resistive range (if it hasn't got a cap,)
Just be aware doing this in circuit you may actually be measuring something else.
(but this could indicate the caps not shorted anyway)
Its little things like that, that can cause you to go on wild goose chases.
HTH
Cheers
You step into the Road, and if you don't keep your feet, there is no knowing where you may be swept off to." Bilbo Baggins ...Comment
-
I know I've been a little scarce lately (like the last 2-3 years), but I'm still here and still doing my thing with fixing PSUs.
For today's considerations, I have a Seasonic B12 BC-550 [A551bcafh] 550 Watt ATX power supply for you (click on links for full size images).
https://www.badcaps.net/filedata/fetch?id=3591771
https://www.badcaps.net/filedata/fetch?id=3591772
It's a modern ATX unit with fixed (non-modular) cables and an 80-plus bronze certificate. Here's the label:
https://www.badcaps.net/filedata/fetch?id=359177... -
Hi
Recently I got this tagan tg380-u01 PSU with bad caps on 3.3v rail (the line was 2.5v no load!). Replaced them but no go, so I've replaced all of them, apart from some smaller ones and one under the secondary heatsink. Even that didn't help so I've replaced the others. All caps are known good ones.
Powered it on and heard the breaker pop. Opened it up and saw some smaller caps shorted together. Fixed that up but still it trips breakers. Now I get 0ohms from 5v to GND. Secondary heatsink removed and still a short, even with the PWM IC board removed. All diodes on that... -
Hi guys, i was wondering, i've got 9Ohms on Vmem, one of the mosfet was shortet to ground, so i've desoldered hi and low mosfets nad still low res, then i removed all of the memory chips, and the resistance is still low, so did you had maybe a card with that low res on memories, and the card was working fine ?
Removed the U1866Q and still without result, i dont have thermal cam so can't see where is hot spot when incjeting voltage.
The resistance on core is ok 0.1Ohm ((Power 0.8V when on)
Resistance on 12V 4K ohms (Power present when on)
Resistance on 12V PEX 4K ohms... -
Hi,
Try to repair a Thinkpad P72 EP720 NM-B723 MB with I7-8850H processor and N18E-Q1-KB-A1 (P3200) GPU with 6GB memory. Unfortunately there is noinfo what happened to the laptop. I got it disassembled with parts missing, like keyboard, battery.
Unfortunately I have no schematic available for me (requested in the sub porum) but got the boardview file.
Symptom: after connecting to the charger the power led light up for one-two second and switch off. After a couple secons the power led light up for half a second and switch off. No battery, no IO board, no... -
Hello,
First, I am a complete noob with high voltage stuff. I'm learning, but I need help by someone looking over my shoulder.
I recently came into posession of a Heathkit IO-4205 5MHz Dual Trace Oscilloscope. The documentation is copyright 1978. I'm told it works.
I opened it up to check the caps before I applied power, and found the following black caps and wanted to know what they were. They are on the power supply board. I was able to read the name and model and came up with, "Nytronics 162J-1, 0.1uF, 20% tolerance, 2000VDC."
...
Comment