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Another EuroPC

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First post, by RetroGizmo

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Hi All!

I'm just looking at a Schneider EuroPC. A few IC's around the battery were dead (373's and 245), but in general vias and traces are pretty intact (one broken trace so far). After replacing the dead IC's it now runs the Ruud diagnostic ROM a little before hanging (external ready line going low and stopping processing around video init).

I have a feeling JIM is dead. 🙁 I can see IOW and A0-9 being correctly asserted on JIM for COM and LPT access but the relevant CS lines from JIM to the rest of the periphals are not going low. My understanding is that JIM is largely glue logic for address decoding and the bridge between the CPU and LPT/COM/RTC.

Does anyone have any better knowledge of JIM's operation and whether it looks like this one is dead? And is there a replacement for JIM? It looks potentially like it's functionality could be guessed pretty accurately for a repro.

Thanks! 😀

Reply 1 of 4, by Toportyán

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Hi RetroGizmo,

do you have any progress with this?

Reply 2 of 4, by RetroGizmo

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Toportyán wrote on Yesterday, 21:38:

Hi RetroGizmo,

do you have any progress with this?

Sadly not yet, no. I've been on the lookout for another EuroPC in the hopes it had a working JIM such that I could figure out exactly what it did to build a repro, but I've not found one in the UK. 🙁

As JIM is definitely dead in mine, I will see if I can get it decapped. I've never tried reverse engineering a chip from a die shot, but this is simple, so could be something to try... 😀

Reply 3 of 4, by Toportyán

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Did u try to reflow the plcc leads?
Did you check the pcb vias neet to varta?
Did u checked all the other pins? eg. the JIM reset (19).
Dir u checked with external vid. card? JIM is very involved in onboard video as well...
Couse its a rare custom asic, decap it if the chip is 101% sure dead 😀

Reply 4 of 4, by RetroGizmo

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Toportyán wrote on 44 minutes ago:
Did u try to reflow the plcc leads? Did you check the pcb vias neet to varta? Did u checked all the other pins? eg. the JIM rese […]
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Did u try to reflow the plcc leads?
Did you check the pcb vias neet to varta?
Did u checked all the other pins? eg. the JIM reset (19).
Dir u checked with external vid. card? JIM is very involved in onboard video as well...
Couse its a rare custom asic, decap it if the chip is 101% sure dead 😀

Yes, I used the Ruud XT 8088 daig ROM and JIM was not generating the correct (any) chip selects . I replaced quite a lot of chips due to battery damage and came to the conclusion JIM is dead.

I'm getting it decapped, so we'll see what the die shot shows us!

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