Repairing a motherboard - Page 1
Forum section: electronics / repair

author: Culbrelai
author_rank: Newbie
timestamp: March 10, 2022, 09:30:41 pm
content: Hello EEVbloggers. Long time fan. Dave got me into trying to repair electronics. One subject of these pursuits is thisIt's an ECS (better known in the past as PC CHIPS) K7S5A Pro Rev 5.0As you can see in the photo, it had bad caps. I did not try to power it on in this state, instead I replaced all of the bad caps. Trying to turn it on now with a known good power supply, RAM, and graphics card. The board powers up for a few seconds, the fan spins and then it turns back off. I was only able to get display out of it once, just a blinking cursor.What are your thoughts? Bad BIOS chip? I'm pretty much a noobie, no access to an oscilloscope but I do have a multimeter.

author: testpoint1
author_rank: Frequent Contributor
timestamp: March 13, 2022, 06:46:04 am
content: it is a quite old board, if you want to practise to repair the MB, you can select intel Z97 chipset to do it, just like Asus Z97 series, I have all the boardview for that.

author: Vovk_Z
author_rank: Super Contributor
timestamp: March 13, 2022, 07:12:50 am
content: 1. Check all soldering points if there is excessive solder blobs.2. Reset the BIOS.3. Check power supplies.

author: Towger
author_rank: Super Contributor
timestamp: March 13, 2022, 08:01:20 am
content: As per Vovk_Z and check if the battery is flat/low voltage.

author: PKTKS
author_rank: Super Contributor
timestamp: March 13, 2022, 08:37:36 am
content: Usually you will not need scopes for thatBut a couple of things you will be required to have around...A very good pre heater for mobos... large and with holdersA good POST BIOS code reader card..A very good set of dessoldering needles for the caps..Also dealing with old board you need to clean them and most time corrosion and moisture damage is the problemCleaning is a very long topic...Paul

author: whatboy
author_rank: Regular Contributor
timestamp: March 13, 2022, 04:11:19 pm
content: Use a white "pelican" eraser to clean memory contacts, reseat the BIOS chip, make sure RTC bat has juice, replace CPU.

author: nightfire
author_rank: Frequent Contributor
timestamp: March 13, 2022, 04:17:10 pm
content: I second the stuff with the POST card mentioned above. At this stage you will want to know at which point of initialization the mainboard fails, and have the List of POST codes (BIOS/mainboard dependant) ready.

author: Vovk_Z
author_rank: Super Contributor
timestamp: March 13, 2022, 08:25:22 pm
content: Quote from: whatboy on March 13, 2022, 04:11:19 pm+1. I forget to write about cleaning memory contacts. After soft mecanical cleaning with an eraser they must be cleaned with any PCB cleaner.

author: abdulbadii
author_rank: Frequent Contributor
timestamp: March 16, 2022, 02:41:57 pm
content: memory contacts cleaning by rubber eraser is so commonly nice benefit in PC repair techniquebut please know a point: acids used in making them may damages the contacts, try find out a natural gum eraser which would not damage the contacts, as they are made without acidsCheck thermal paste, might be has aged

author: Ed.Kloonk
author_rank: Super Contributor
timestamp: March 16, 2022, 05:43:43 pm
content: Quote from: Culbrelai on March 10, 2022, 09:30:41 pmHoly moly. I like how you chose something simple to dive into.Regarding the memory/dimm modules, a good memtest can identify crap sockets or dimms. And frankly, general board health.https://www.memtest86.com/Some Linux distros come with it included in the ISO.