Author Topic: Wanted - any Johannus control board with 88C25 chips  (Read 1785 times)

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David Pinnegar

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Wanted - any Johannus control board with 88C25 chips
« on: September 26, 2016, 05:24:53 PM »
Hi!

My instrument is somewhat desperate for some donor 88C25 chips. Something odd has gone wrong with stop control and capture so it's a case of trying one thing and another. Possibly the EEPROM has failed, which is nasty, as then we're reliant on being able to clone the program from another Johannus MD339 compatible instrument . . .

Best wishes

David P

dragonser

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Re: Wanted - any Johannus control board with 88C25 chips
« Reply #1 on: September 27, 2016, 09:44:36 AM »
Hi,
after looking up the part number would it be a delay circuit with voltage detector ?
or have I got the wrong IC ?
Is the eeprom used to save/ restore the stop settings ? if so then it is possible that it could have failed ?
or does it have a unique program in it as well ?
regards Peter B

David Pinnegar

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Re: Wanted - any Johannus control board with 88C25 chips
« Reply #2 on: September 27, 2016, 08:17:11 PM »
Thanks - no it's not a delay and voltage detector but an interface for the 8088 processor. My hunch is on the EEPROM failure :-(

Best wishes

David P

 


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