Saving an IBM PC board by re-soldering a power supply slot - Page 1
Forum section: electronics / repair

author: highcap
author_rank: Contributor
timestamp: January 09, 2024, 08:04:45 pm
content: I really want to save this board and avoid its scraping fate.As you can see from the images someone left a total mess.My biggest concern is (if) the board is having a middle layer where connections are made, which I might not be able to re-connect.Any thoughts can be of help, thank you.

author: fzabkar
author_rank: Super Contributor
timestamp: January 09, 2024, 09:20:02 pm
content: How can you be certain that the board isn't faulty and that someone hasn't just cannibalised it?

author: highcap
author_rank: Contributor
timestamp: January 09, 2024, 09:57:08 pm
content: I'm not certain, so I need to find out.This slot/area is the only damage the board is suffering, rest looks clean.I'm guessing someone pulled the power cable too hard and made some damage, then the repair attempt failed catastrophically...Forgot to click reply button @fzabkar

author: BlownUpCapacitor
author_rank: Frequent Contributor
timestamp: January 09, 2024, 10:55:11 pm
content: Is it a multi layered PCB? Because it looks like it as I don't see surface traces coming out of some of the raped pin holes of that board.If it is multi layer (more than 2 layers) then it is near impossible to fix.

author: highcap
author_rank: Contributor
timestamp: January 09, 2024, 11:51:29 pm
content: It seems it is multi-layer, this is what I'm afraid of.So there's not any methods to 'touch' that middle layer wiring again?

author: BlownUpCapacitor
author_rank: Frequent Contributor
timestamp: January 10, 2024, 12:30:27 am
content: I've seen people use a TCT drill bit to carefully drill a new hole, then use a high-angle countersink bit, such as a 120-degree bit, to expose the traces underneath. Then sand it down and clean it up, then use an exacto knife to pick away at the FR4 material to solder.I don't remember where I saw this (I think it was Hackaday or maybe a YouTube video) but I don't really recommend it as there is minimal room for error.

author: rsjsouza
author_rank: Super Contributor
timestamp: January 10, 2024, 12:47:50 am
content: This board is multilayer - the connections to C99 and C100 go nowhere on both outer layers, so they are internal.In these cases I would evaluate the cost of a similar one on the used market before spending much time with it. If it is worth the attempt, solder a new connector and test it. If it does not work, scrap it. If it has sentimental value, frame it. Not much else can be done, unfortunately.

author: coromonadalix
author_rank: Super Contributor
timestamp: January 10, 2024, 01:46:58 am
content: nah to much damage on this one canibalized is a poor wiord, it was destroyed, maybe there was problems on this board before,normally nobody play with this connector ??send it to recycling

author: highcap
author_rank: Contributor
timestamp: January 10, 2024, 12:27:22 pm
content: This is what I wanted to hear, one of the possibilities even if small chances.I have thought about making drills, but the high-angle countersink bit advice was the key element I lacked.I will get back with updates if solved.Thank you!

author: SeanB
author_rank: Super Contributor
timestamp: January 10, 2024, 12:56:18 pm
content: Have fixed those, but, since the cost of a replacement board was in the order of $10k, it was a case of spend a week carefully scraping off layers, then getting the planes exposed, and soldering on thin strands of wire, and then at the end using epoxy to rebuild the layers, before putting the capacitors back. Wet slug tantalum capacitors with rubber seals are a curse, the acid weeps through that seal, and rots the board away. Did glue down the new glass seal ones, and for those unable to get went to aluminium electrolytic, accepting they would have a 1 year life, but at least would be easy to replace then.

author: pcprogrammer
author_rank: Super Contributor
timestamp: January 10, 2024, 02:18:20 pm
content: To make sure the board is functional, you could see if the needed voltages can be connected somewhere else on the board. One of the expansion connectors for example.Just solder wires to the points found with the needed voltages and see if the board works. If so you can also use bodge wires to the points found to connect the new power connector.If it is an old board you are looking at +/-12V and +/-5V. Otherwise 3.3V comes into play and some of the negative voltages might not be needed.

author: Stray Electron
author_rank: Super Contributor
timestamp: January 10, 2024, 02:30:04 pm
content: Just a thought here. What is that connector used for and how many of the pins are used?I think it will be impossible to fix that connector but if not too many of the pins are used, then you might be able to by-pass the connector and connect wires directly to the component that each contact connects to. That may or may not work, depending on signal timing and speed and possible noise pickup.I have jury rigged equipment like that in the past but I don't know if it would work with a modern or even semi-modern computer. I agree with the others here, go to Ebay or somewhere like that and buy a replacement board or computer.

author: asis
author_rank: Frequent Contributor
timestamp: January 11, 2024, 03:12:37 am
content: Hi,Everything is really being restored.Keep in mind that on the side of the PSU connector (female' s) there is mirror indexing.https://www.smpspowersupply.com/connectors-pinouts.html

author: amyk
author_rank: Super Contributor
timestamp: January 11, 2024, 03:47:15 am
content: Schematics are available, put connector in place with structural solder and then run bodge wires to suitable other places where the tracks surface.

author: pickle9000
author_rank: Super Contributor
timestamp: January 11, 2024, 06:08:35 am
content: These are pretty helpfulhttps://www.chemtronics.com/circuitworks-conductive-penThe "ink" is a very fine silver powder. Works OK with lead based solder. Scrape back but only to expose copper.Leave the connector as high as possible so you can see under it. If your working electrically epoxy the connectorto the pcb and pray to the lord of silicon heaven.

author: pickle9000
author_rank: Super Contributor
timestamp: January 11, 2024, 06:13:16 am
content: Soldering wires to a connector is a very good option but looks very crappy.

author: pickle9000
author_rank: Super Contributor
timestamp: January 11, 2024, 06:34:09 am
content: One tip, flux and solder the perimeter of the hole if there is copper and you can reach it, it will tin up and make it much easier to see.Copper tape used for stained glass can be used to make a thruhole.