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Old 02-21-2023, 02:27 PM   #1
Hachune
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Lightbulb DIY Bench Power Supply Question

Hi,
I really need a bench power supply for finding shorts. I am a hobbyist and never had one before, I still plan to buy one in the future but will this setup work for the time being?



1. ATX PSU - I have multiple of them lying around (albeit old stuff), I believe they can provide pretty high amps on 12v rail.
2. Buck converter with variable voltage and amp control with a volt/amp meter. Link to the product : https://robu.in/product/5a-cnc-dc-dc...supply-module/
3. A multimeter probe at the output.

I plan to desolder all other voltage wires except +12v, a ground wire and PSON (green wire). But I have no idea if it will work as intended. I have no other plans of usage except for finding shorts in a mostly a PC motherboard and graphics card.

Please help me out. Thanks.
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Old 02-23-2023, 06:46 PM   #2
harp
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Default Re: DIY Bench Power Supply Question

The ATX PSU for most short finding is overkill.
I use the common small wall adapter 12v/1A with similar module setup, current limit, v addjust and display...

But, it nice to have proper linear bench psu

BTW, what is your prefered plan/method to find shorts component?

Last edited by harp; 02-23-2023 at 06:49 PM..
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Old 02-23-2023, 08:26 PM   #3
sam_sam_sam
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Default Re: DIY Bench Power Supply Question

My preference is to use the 3.3 volt rail and maybe the 5 volt rail and use a lm317 in the current mode you could even use the 12 volt rail but only after you determine whether or not you actually have a short

But if go with a lm317 regular in the current mode please use a good size heat sink for this application

Or you use something like a buck converter for this

https://www.ebay.com/itm/224143044400

If use this type of buck converter please make sure that you can turn the current all way down to about 50 milliamperes or so “0” milliamperes some of these boards are not going to work properly

Case in point I bought 5 of them and one of them the current section did not work correctly but the meter section did it was a good thing that I had bought 5 more of them but without the meter

If you decide to go with this idea do yourself a favor and replace the pot controls with something that can stand to be moved up and down repeatedly because the pot controls that are on there are not meant to be used that way
__________________
9 PC LCD Monitor
6 LCD Flat Screen TV
30 Desk Top Switching Power Supply
10 Battery Charger Switching Power Supply for Power Tool
6 18v Lithium Battery Power Boards for Tool Battery Packs
1 XBox 360 Switching Power Supply and M Board
25 Servo Drives 220/460 3 Phase
6 De-soldering Station Switching Power Supply 1 Power Supply
1 Dell Mother Board
15 Computer Power Supply
1 HP Printer Supply & Control Board * lighting finished it *


These two repairs where found with a ESR meter...> Temp at 50*F then at 90*F the ESR reading more than 10%

1 Over Head Crane Current Sensing Board ( VFD Failure Five Years Later )
2 Hem Saw Computer Stack Board

All of these had CAPs POOF
All of the mosfet that are taken out by bad caps

Last edited by sam_sam_sam; 02-23-2023 at 08:35 PM..
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