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Am5x86-P75 & LS-486e Rev. C

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First post, by GoldenPentium

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Hello everybody,

I bought Am5x86-P75 133 ADW to my collection and it seems that CPU came already broken. Computer doesn't start. My jumpers' setup below.

The attachment ls-486e-5x86.png is no longer available

After the some experiments I figured out that CPU has only 167 pins - pin D28 is missing (damnit). What is the purpose of this pin? Could it be the reason of malfunctioning? Is that possible to solder a new pin to fix it?

Reply 1 of 4, by majestyk

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D28 is one of the 32 I/O (Data) pins, so it´s necessary for operation.

Reply 2 of 4, by Disruptor

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GoldenPentium wrote on 2022-09-10, 01:28:

Is that possible to solder a new pin to fix it?

Yes. Perhaps you try to solder a leg of a LED on the CPU.
But check before if the leg fits into the CPU socket.

Reply 3 of 4, by GoldenPentium

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So, it was definitely broken CPU. Got refund and then bought a new one - ADZ. Now everything works fine.

Thank you all!

P.S. anyways, will try to fix ADW though.

Reply 4 of 4, by rasz_pl

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Instead of soldering new leg you can experiment with fitting cut to length resistor/led leg into the socket, then installing CPU over it in a way it constntly pushes into that leg

https://github.com/raszpl/sigrok-disk FM/MFM/RLL decoder
https://github.com/raszpl/FIC-486-GAC-2-Cache-Module (AT&T Globalyst)
https://github.com/raszpl/386RC-16 ram board
https://github.com/raszpl/440BX Reference Design adapted to Kicad

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