Here is a quick lesson in fault finding a power rail short A low resistance meter.
First up, a proper low resistance meter..
Basically what we do is check the resistance across various capacitors around the board and look at the resistances.
I started at the bottom right corner of the board working my way up with and to the left taking note of the resistance. Which is 84.2mR.
Moving upwards on the board you can notice the resistance gets slower, so we are getting closer to the short! Now 35.9mR!
Now I can only move to the left. So moving along one by one the resistance got lower and lower until there was nowhere else to go...
This is the lowest resistance point on the whole board on the power rail at 11.3mR.
So checking what capacitor that is on the PCB files...
..And yes this was a PCB oopies the problem.
I have diagnosed failed ceramic capacitors on motherboards this way as well.
Overall a low resistance meter is a very useful piece of kit when you have something short circuit on the motherboard. Like on the power rails and have no idea where short actually is.
Finding a power rail short with a low ohmic meter
Finding a power rail short with a low ohmic meter
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viewtopic.php?f=17&t=1585 Have you done the Mandatory Fixes ?
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https://www.exxosforum.co.uk/atari/store2/ - All my hardware mods for sale - Please help support by making a purchase.
viewtopic.php?f=17&t=1585 Have you done the Mandatory Fixes ?
Just because a lot of people agree on something, doesn't make it a fact. ~exxos ~
People should find solutions to problems, not find problems with solutions.
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Re: Finding a power rail short with a low ohmic meter
There's a good video on YouTube an TV repair engineer shows you how to fix a TV doing this and then he showed you how to build your own meter.
He gets the circuit from an old electronics mag it works really well
Brian
He gets the circuit from an old electronics mag it works really well
Brian
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- Posts: 152
- Joined: Sat Apr 03, 2021 2:08 am
Re: Finding a power rail short with a low ohmic meter
Oh I forgot another way way is to use a flir usually your short gets very hot very fast I use the flir on my phone for exactly this. I got this phone specifically for the flir.
Utr
Utr