modem7
10k Member
In the 5150, the BIOS ROM is the one which if it fails, results in the 'dead' symptom. He's already swapped that out - in his first post is "-Switched BIOS with known-good one."
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5150 Mainboard Troubleshooting
- Thread starter IBM
- Start date
U15, U16, U17 and U23 are all toast.
When I said that there were no obvious signs of damage to the board, that was only partially true. I did notice that those four ICs look slightly… melted. I know you’d think that would be an obvious problem, but they look sound. The surface is just a bit wavy and glossy – the text is still very clear and there is no reason to think this is anything but a cosmetic defect.
No reason to think that at all….
Ok, so today I tracked down the computers original owner – a friend of a friend who is almost 80 years old and a retired engineer. He was the one who gave the (apparently nonfunctional ) computer to an old friend who, after keeping it without trying it or knowing it didn’t work for a decade, gave it to me. So I talked to his old friend on the phone today and he told me that he had to “set a few” the ICs with a heat gun to fix some intermittent problems. I asked him to elaborate and he said that he was having problems with this board back when he was still using it in the late 80’s, and he checked various ICs and found that he needed to “set” them. He claims this is a technique that anneals the circuit and can fix certain errors if you know what you are doing. Wow, I cannot believe that. I really can’t. He used a heat gun on a motherboard… that just takes the cake. I can see no reason why that would work – but the man did work as an engineer for IBM for decades and you’d think he’d know his stuff… but he really does belong in a nursing home. Hasn’t aged as well as I have What a crazy thing to do. I see now that these are just standard logic and I could replace them, but I don’t think it’s worth the effort to take off and replace that many chips. I have been needing some replacement capacitors and other parts, so I think I will just salvage a few parts instead (especially that cassette relay – mine gets used so much I’m worried it will wear out eventually).
Well, thanks for helping. I still can’t believe it – death by heatgun!
-Isaac
When I said that there were no obvious signs of damage to the board, that was only partially true. I did notice that those four ICs look slightly… melted. I know you’d think that would be an obvious problem, but they look sound. The surface is just a bit wavy and glossy – the text is still very clear and there is no reason to think this is anything but a cosmetic defect.
No reason to think that at all….
Ok, so today I tracked down the computers original owner – a friend of a friend who is almost 80 years old and a retired engineer. He was the one who gave the (apparently nonfunctional ) computer to an old friend who, after keeping it without trying it or knowing it didn’t work for a decade, gave it to me. So I talked to his old friend on the phone today and he told me that he had to “set a few” the ICs with a heat gun to fix some intermittent problems. I asked him to elaborate and he said that he was having problems with this board back when he was still using it in the late 80’s, and he checked various ICs and found that he needed to “set” them. He claims this is a technique that anneals the circuit and can fix certain errors if you know what you are doing. Wow, I cannot believe that. I really can’t. He used a heat gun on a motherboard… that just takes the cake. I can see no reason why that would work – but the man did work as an engineer for IBM for decades and you’d think he’d know his stuff… but he really does belong in a nursing home. Hasn’t aged as well as I have What a crazy thing to do. I see now that these are just standard logic and I could replace them, but I don’t think it’s worth the effort to take off and replace that many chips. I have been needing some replacement capacitors and other parts, so I think I will just salvage a few parts instead (especially that cassette relay – mine gets used so much I’m worried it will wear out eventually).
Well, thanks for helping. I still can’t believe it – death by heatgun!
-Isaac
modem7
10k Member
Death by heatgun. What a horrible way to go. There should be a law against it.
I've never heard of it myself, but there could be something to it. Sounds like something one would do only as a last repair effort to some kind of PCB problem. Maybe others on this forum have heard of the technique and can elaborate.
per
Veteran Member
The only thing I could imagine it would fix was any cold soldering joints, but using a heatgun for that is still very risky. It can damage both the components and the PCB itself.
Chromedome45
Veteran Member
Whhoops my bad I should have read the post more carefully. Man that sucks. I too have never heard of using a heatgun to fix an intermittent problem. Soldering iron yes. Well hope you can find another 5150 MB at a reasonable cost. Good luck