Reviving an IBM PC AT 5170 Type 2 board

[Carles20VT]

Hello to all members!

I'm trying to revive my IBM PC AT 5170 with Type 2 Mainboard. It's completely dead and no bot.

The short history was I killed it .

Long history... When I was very young, a school teacher give me this computer when school decommissioned all old computers in favour of new Pentium 100 rigs. I learned a lot playing with it. But finally, I killed it when tried some overclock configurations (Oscillators and CPUs).

Now I'm trying to revive the board. So I will detail what I have done until now:

• All memory ICs have been replaced.
• Checked all caps to check shorts.
• Replaced the IC Intel D82284-8 (Clock Driver and Ready Interface) with an Intel D82284-10 (socketed).
• Replaced the IC Intel D82288-8 (Clock Driver and Ready Interface) with an AMD 82C288-10 (socketed).
• Reset the CPU (Intel 80286-6).
• Reset the original 12Mhz clock oscillator.
• Change the IBM BIOS with a generic AMI BIOS ( Tested the EPROMs with another 5170).

I bought a diagnostic ISA card to try to discover what happens. The most of the time the displays show "--" and nothing changes. The RESET led changes to IRDY as expected but then it freezes. Sometimes it displays some code like "01", "96", "FF"...

I suspect that the CPU is dead... sometimes it runs but then freezes. I ordered a socket adapter to try a spare CPU that uses the LCC socket.

Can I check or try another thing?

Thanks in advance!

 

[MauriceH]

You did a over clock back than.
So my idea is to begin with the cpu.

Look at your manual from the pc test card
what is the first or second in the
bios step. 00 and 01.
Try to buy a cheep oscillosscope.
Then you can see if datalines are active.

On ebay lots of them.
Than you f.i can see if C tal is running
data lines. or 1 line dead etc.

 

[Carles20VT]

You did a over clock back than.
So my idea is to begin with the cpu.

Look at your manual from the pc test card
what is the first or second in the
bios step. 00 and 01.
Try to buy a cheep oscillosscope.
Then you can see if datalines are active.

On ebay lots of them.
Than you f.i can see if C tal is running
data lines. or 1 line dead etc.

Thanks for your reply.

I'm waiting for a new CPU just now.

By the way, I will try to pickup one oscilloscope to check these lines, and it would be util to other repairs too. Great idea!

 

[Malc]

If you can burn your own Eproms and have a suitable video card / Monitor you could try the Supersoft diagnostic ROMs for the 5170 and see if they shed any light on the problem. http://minuszerodegrees.net/supersoft_landmark/Supersoft Landmark ROM.htm

 

[Carles20VT]

​Helo to all,

Finally, I have good news :D

First of all, sorry for the long reply. I was busy, and I couldn't find time to work with the board until now.

The problem was a Bios socket!!! As stupid as it. After some EPROMs changes, I can see how sometimes the diagnostic ROM starts to display something and sometimes nothing.

After digging a little, I checked the socket and found some internal pins bend or different aperture. So, I put the original BIOS inside, cut small wires to ensure the contact, and voila... the motherboard started to count RAM.



Finally, I replaced the socket with the new one. No more future problems this socket will give to me.



Thanks to all :D And now... I will continue the battle with a dead CGA card and crazy Expansion Ram.​

 

[modem7]

The problem was a Bios socket !!!

Thank you for the update. I have added the failure to the list at [here].