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Tkhtpc
August 11th, 2017, 05:10 PM
(I'm very new to all this just trying to learn)

So I have a ibm 5160xt with a 256-640KB motherboard, 5/09/86 bios chips( U18=59X7268, U19=62X0819 ) it has been rewired like the picture from http://minuszerodegrees.net/5160/motherboard/5160_u18_u19_socket_mod.png

the PSU has correct voltages under load with everything removed. I reseated all the ram and replaced the first two banks with this ram http://www.jameco.com/z/41256-120-Major-Brands-256KX1-DIP-16-DRAM-150NS_41398.html?CID=GOOG&gclid=Cj0KCQjwq7XMBRCDARIsAKVI5QaYkcBWZpsV1mI9zXGD 0p1mHq7wu4yGFeyOVhkTWuX8N3kn-1Hi750aAlpvEALw_wcB after the reseat didn't work. I am not getting any life short of the PSU fan spinning I have left it on for 20min, no beeps. I found this sight http://www.mtmscientific.com/pc-retro.html and ordered the PC-RETRO OPTIONS: IC ADAPTER with DIAGNOSTIC ROM, but I dont think I can use it since it's only one chip not the two that the xt takes. any advice would be greatly appreciated.

Flamin Joe
August 13th, 2017, 06:56 PM
A short in one of the Tantalum caps is the most likely cause. It's a very common issue with both the 5150 and 5160.

Follow the diagnostic instructions below:

http://www.minuszerodegrees.net/5150_5160/MDC/minimum_diag_config.htm

max5160
August 14th, 2017, 08:01 AM
In my case it was U18 (the first ROM chip) that was faulty.

I have been able to burn myself a new one and now my 5160 boots.

On minuszerodegrees.net you can also find a similar diagnostic ROM.

modem7
August 15th, 2017, 12:33 AM
So I have a ibm 5160xt ...

I found this sight http://www.mtmscientific.com/pc-retro.html and ordered the PC-RETRO OPTIONS: IC ADAPTER with DIAGNOSTIC ROM, but I dont think I can use it since it's only one chip not the two that the xt takes. any advice would be greatly appreciated.
The PC-RETRO Kit is a copy of the IBM 5150. The adapter is required for the PC-RETRO because of the ROM type used in the 5150/PC-RETRO. The adapter is not applicable to the IBM 5160, but you will be able to use the Supersoft/Landmark Diagnostic ROM.


... but I dont think I can use it since it's only one chip not the two that the xt takes.
Per [here (http://www.minuszerodegrees.net/supersoft_landmark/5155_5160/256KB-640KB.htm)], you place the Supersoft/Landmark Diagnostic ROM in socket U18.

per
August 15th, 2017, 04:54 AM
The rewire is just a small mod IBM made since the later XTs use 32KB ROMs instead of a mixture of 32KB and 8KB ROMs. It's actully the only physical difference between the 1984 second revision 64-256K and 256-640K motherboard PCBs.

lyonadmiral
August 15th, 2017, 05:18 AM
In my case it was U18 (the first ROM chip) that was faulty.

I have been able to burn myself a new one and now my 5160 boots.

On minuszerodegrees.net you can also find a similar diagnostic ROM.

I am curious guys, exactly how does a ROM chip go bad?

modem7
August 15th, 2017, 01:46 PM
I am curious guys, exactly how does a ROM chip go bad?
Answer #1: By hanging out with the wrong crowd :-)

Answer #2: It can fail in the same ways that any other TTL chip on the montherboard can fail.