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I destroyed an IBM PS/2 8530 286

U

upnorth

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This is a model 8530-H31 - which is, as far as I can tell, equivalent to the 8530-E31. Or, I should say, was.
Thus the destruction happened: I had errors 161 and 163, which indicated a flat battery in the Dallas RTC. So I removed the chip, and proceeded to mod it with an attached coincell battery. Then I replaced the modded Dallas, but in the process I inserted it in the wrong orientation. There was no image, no memory count, the drive would not spin up, and there was no beep prompting to press F1 on the keyboard. Finally I realized the issue with the Dallas chip's orientation. When I removed it, I noticed it was burning hot. I tried to put it in the correct orientation, but to no avail, the machine is dead. The HD seems to try to spin up but soon enough slows down again, without any seek sound.

Right now I am extremely upset. I was hoping that writing this would make me feel a bit better, but it's just marginal.
Extra upsetting because this machine cost me quite a lot of money.

I wonder if there is anything salvageable. Maybe the CPU, the memory modules, the HD and the floppy drive? But everything else is a write-off. I have no chance to repair the motherboard, even if I knew which of these SMD chipset ICs have been fried. And the case is completely useless without the motherboard. No other motherboard would fit inside. And no motherboard is compatible with this PSU.
 
I think there's a good chance it's not actually destroyed, and is almost certainly not fully a write-off . What happens when you remove the Dallas RTC entirely? Does it turn on? It will probably not POST (and if it does it will definitely have errors) but if the drive spins up you're likely well on your way to a fairly complete recovery. This Dallas RTC is definitely destroyed, though. Throw it out. Don't re-install it.

You might still be correct about it being a write off. But I wouldn't jump to that conclusion just yet.
 
Yeah, the Dallas may have fused together and become a short, shutting down the power supply.
 
bear said:
I think there's a good chance it's not actually destroyed, and is almost certainly not fully a write-off . What happens when you remove the Dallas RTC entirely? Does it turn on? It will probably not POST (and if it does it will definitely have errors) but if the drive spins up you're likely well on your way to a fairly complete recovery. This Dallas RTC is definitely destroyed, though. Throw it out. Don't re-install it.

You might still be correct about it being a write off. But I wouldn't jump to that conclusion just yet.
Click to expand...
It behaves exactly the same as when the Dallas was inserted.
 
hmm, that's not very good. but I think there's not much you can actually have killed besides the RTC, with it in backward. You end up with power and ground swapped on the RTC, which is what would kill that. but you can't put battery voltage out into the motherboard. and if you could it's only 3v... you could maybe blow some internal RTC circuitry in such a way that you unexpectedly drive some logic lines, but it's still a 5v part and the only think that's likely to come out is a 5v logic high... not dangerous. The worst thing I can think of is potentially ending up with ERASE on one of the multiplexed address/data lines and consequently grounded, which, from reading the datasheet, I think must connect the battery to something internally (though this is supposed to only happen when the thing is operating on Vbatt) and is maybe, since it sounds like the PSU wasn't even operating while the RTC was in backward, the likely reason the thing got so hot.

You might have just gotten bad luck with timing on an HDD failure. They don't last forever. I still think it's worth acquiring a replacement DS1287, even a dead one, and trying the machine with that before panicking too much.

edit: I meant "even a DS1287 with a dead battery", not "a dead DS1287"
 
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A PS/2 does nothing without a working RTC/CMOS chip.

To see what is really wrong (if anything), you need to install a new, working Dallas first. The system may just work fine. You can not do any trouble-shooting as long as the Dallas chip is not fixed.
 
Exactly what Dalas chip was it, and how did you do your battery modification?

From the pinout of the device, we may be able to work out what pins were affected when you plugged the device in the wrong way around.

This will, hopefully, narrow the diagnostic field down if a replacement doesn't fix the problem.

Dave
 
bear said:
hmm, that's not very good. but I think there's not much you can actually have killed besides the RTC, with it in backward. You end up with power and ground swapped on the RTC, which is what would kill that. but you can't put battery voltage out into the motherboard. and if you could it's only 3v... you could maybe blow some internal RTC circuitry in such a way that you unexpectedly drive some logic lines, but it's still a 5v part and the only think that's likely to come out is a 5v logic high... not dangerous. The worst thing I can think of is potentially ending up with ERASE on one of the multiplexed address/data lines and consequently grounded, which, from reading the datasheet, I think must connect the battery to something internally (though this is supposed to only happen when the thing is operating on Vbatt) and is maybe, since it sounds like the PSU wasn't even operating while the RTC was in backward, the likely reason the thing got so hot.

You might have just gotten bad luck with timing on an HDD failure. They don't last forever. I still think it's worth acquiring a replacement DS1287, even a dead one, and trying the machine with that before panicking too much.

edit: I meant "even a DS1287 with a dead battery", not "a dead DS1287"
Click to expand...
Thanks, you gave me some material to think about.
BTW, if I have blown the 5V line of the PSU, that would be easy enough to check. Unfortunately, my model 30 has the weirdest PSU pinout imaginable. According to the PS/2 Hardware Maintenance Manual (find it e.g. at http://ohlandl.ipv7.net/books/ps2-hmm.pdf ) my PSU is a weird hybrid of a Model 30 and a Model 55. Please kindly see the attached photo and compare with diagrams on pages 138 and 141 of the PS/2 HMM. This is one of the curses of having a rare PS/2 model, I assume.
 

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Timo W. said:
A PS/2 does nothing without a working RTC/CMOS chip.

To see what is really wrong (if anything), you need to install a new, working Dallas first. The system may just work fine. You can not do any trouble-shooting as long as the Dallas chip is not fixed.
Click to expand...
This turns out to be the key fact, and the key misunderstanding I had of the system: I assumed that, even without the RTC chip installed, the system would behave as with the RTC battery being flat/empty, i.e. I expected to at least see the error codes 161 163. I was mistaken! Once I have inserted a replacement DS1287 - specifically, the nwX287 RTC module https://github.com/necroware/nwX287
And now the machine works again! Thank you for your helpful remark. I admit, initially I didn't quite believe it, but you were right.

But now, of course, the floppy drive doesn't work so I can't run the setup. I will have to replace the FD with a generic 1,44 MB drive, but the adapter I purchased from TexELEC doesn't work for my 8530 286. That adapter uses an edge connector, whereas my PS/2 uses a 34 pin IDC connector on the mainboard.
 

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  • PS2_8530-H31-FD_Connector.jpg
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Sir_Fartalot said:
This turns out to be the key fact, and the key misunderstanding I had of the system: I assumed that, even without the RTC chip installed, the system would behave as with the RTC battery being flat/empty, i.e. I expected to at least see the error codes 161 163. I was mistaken! Once I have inserted a replacement DS1287 - specifically, the nwX287 RTC module https://github.com/necroware/nwX287
And now the machine works again! Thank you for your helpful remark. I admit, initially I didn't quite believe it, but you were right.

But now, of course, the floppy drive doesn't work so I can't run the setup. I will have to replace the FD with a generic 1,44 MB drive, but the adapter I purchased from TexELEC doesn't work for my 8530 286. That adapter uses an edge connector, whereas my PS/2 uses a 34 pin IDC connector on the mainboard.
Click to expand...
I think this is the floppy drive adapter you're looking for: https://www.ebay.com/itm/304382610986
 
HoJoPo said:
I think this is the floppy drive adapter you're looking for: https://www.ebay.com/itm/304382610986
Click to expand...
Thanks. That looks exactly like what I need, but I was wondering if I could simply modify a normal 3,5" floppy cable? I have plenty of such cables, and am running out of money. All I would need is to cut the cable and resolder the wires correctly. Add also a mini molex for the floppy power.
 
Sir_Fartalot said:
Thanks. That looks exactly like what I need, but I was wondering if I could simply modify a normal 3,5" floppy cable? I have plenty of such cables, and am running out of money. All I would need is to cut the cable and resolder the wires correctly. Add also a mini molex for the floppy power.
Click to expand...
This video shows the cable modifications needed to remove power from the floppy connector and break out that power for a standard 4 pin.
 
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