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Amiga computer related discussion => Amiga Hardware Issues and discussion => Topic started by: amiga4001 on October 16, 2005, 09:59:32 AM
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Trying to rescue a dead mobo (A4000) here.
Latch U177 and battery have been removed(have leaked).
Computer did nothing(only powerlight) with nothing attached.
All I can find for replacement is a 74HCT174 dip package.
Will this do for replacement?
Original it was a 74HCT172D difference?
Should the system show anything with no latch soldered?
PSU is allright and so is processor,buster,and roms checked them in other mobo.
No chips are getting warm and did the rtc check to find broken tracks...nothing.
Hoping it is the latch I mentioned.
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Try asking Flurk at rudi@rackserver.be for advice. He´s our favourite technician in the club and speaks the same language as you :-D
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The system will run without U177.
If the leakage was bad, it may have affected U891 which may have damaged the memory interface. The system will not boot without chip memory.
There are 3 tracks which run through the real time clock area, these commonly get corroded open circuit and may cause booting problems.
Time to start checking tracks and vias in the corroded area for being open circuit.
I've written various technical guides on this kind of thing, most aimed directly at the A4000D:
http://amiga.serveftp.net/hardware_repair.html
I can also supply the correct replacement part for U177 ex stock if required.
Non booting can be tricky to solve without the right test equipment and knowledge. Email me if you need some more help.