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Old 21st Mar 2020, 9:49 pm   #324
DeltaAlpha52
Tetrode
 
Join Date: Feb 2020
Location: Crawley, West Sussex, UK.
Posts: 77
Default Re: MK14 schematic revisions

It works !!

Thanks for the Prom reader sketch - I used an Arduino UNO and checked the roms and they seemed to be fine. After that I used a data probe to check the data and address lines. All were pulsing like I thought they should until I came to address A7, took a bit of time to identify it, but A7 was being held low. No wonder it was not working.

The fault was where I had soldered the power connector wires and not cut the excess of the negative wire - in too much of a hurry to power it up and see if it worked . The negative wire excess bit underneath the board was short but long enough to connect to the A7 line next to IC3. It had worked okay until I had pushed the board down and that had pushed the wire onto the A7 line. I've removed the offending excess wire and now it is working again.

Ah well I've learnt a lot about the build of the MK14 whilst trying to fix this, now to put on a keyboard and look towards the automatic key entry attachment.

Cheers
time for
David
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