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Couple of board repairs


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Heres an Impact motherboard ive been working on for a friend the last few weeks.

There were stray volts as 'noise' on the bus lines when testing, unfortunately there's no schematic for Impact so I marked out everything on the data lines with the intention to start pulling and testing looking for a fault.

I stopped and thought about it and decided to have a really good probe around to look for additional clues, before doing anything else.

Going around the 68681 I found 7... yes 7volts! on the IRQ pin which explained why all the bus lines were wild.

The only place in my mind 7volts could be getting on the IRQ line in my mind was a short... and had to be under the game card header- I had a closer look and sure enough there was a tiny bit of old Rot probably been working it's magic for years... the copper was mostly undamaged. By the looks of it, it had gone through the header so had to come off and replace it. Good news all back up and running again now. (Replaced the 68681 and a few other Ics)

Cheers to good old Matthew Potter for posting me the new 96way header and a few other bits.😎

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Edited by MattyL
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  • 1 month later...

Here's a few pics of my latest batch of 5 Scorpion 1's.

Bob has documented the cleaning up stage and the problems with the board surface becoming conductive really well already.

Only thing i can add- I found spraying the stripped area with a little window cleaner makes it literally 10 times quicker. The downside is it's not great for boards and you get a Gloop build up so the area needs alot of rinsing down afterwards... especially underneath components.

I had a few faults to work through on 2 of these.

1, switch matrix fault- test mode always activated. Wrong dipswitch settings. Cause fault at IC16.

2, No lamps. Lamp enable pin stuck hi on the ay8910 (new IC plus cleaned underneath. 

 

One of the boards I tried to colour match the repair mask but the results weren't great so I think I'm keeping that one 🙂

 

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1 hour ago, MattyL said:

Hi folks, I've been pretty busy lately. Here's my System 5 repair I've just finished. Mega happy when this booted up

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Epic board repair, thanks for sharing, glad it was successful.

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