Bombjack

Shinydaz

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Ok this original bombjack has a few issues, but I'm determined to get it working. Armed with my new dataman programmer, its given me a bit more scope, reading and writing eproms that I couldn't do before. I've already spotted a fair few fajitsu's on this board.

Here is a short video of it running.

First I notice on the test screen that the color pallette is all red.

IMG_20170630_14922.jpg


It should be red, green, blue then white.

I was drawn to the 4 ls153's right in the centre of the top board.

Low and behold I found dead outputs on pins 7 and 9 of two of the fajitsu's @ 5h and 5k.

2017-06-30_21.58.55.jpg


Mistakenly label them pin 8 but the outputs are pin 9 as you can see below.

IMG_20170630_21778.jpg
IMG_20170630_37724.jpg


A quick piggyback and its busy outputting again.

IMG_20170630_1535.jpg


And now we have some color back.

IMG_20170630_16209.jpg


Unfortunately I only had one ls153, so I'll have to leave it here, until I can get hold of some more.

Shinydaz2017-07-01 04:50:21
 

Shinydaz

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A bit of spare time today, decided bombjack deserves fixing, well at least the background.

IMG_20170809_39154.jpg


I didn't pull up the schematics, I think the background details are stored at 4P on a 2732 eprom. The dataline's don't seam to be moving, I traced them back to a ls273 at 6S, which is a flip/flop. Shock horror it was a fujitsu and it was bad. Still issues to sort out.

IMG_20170809_17875.jpg


A quick piggyback to confirm, and we have an improvement. Still a bit to go yet.

IMG_20170809_54741.jpg
Shinydaz2017-08-09 18:34:39
 

BarrySlisk

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You do not owe me or anybody else anything..but if you want to pass on some knowledge and make the fixlog more useful for us noobs add more of your thought proces.

"I was drawn to the 4 ls153's right in the centre of the top board."

Why?
 

Shinydaz

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These Fajitsu chips have a high failure Barry, I was just being lazy. I knew roughly the area the problem was and just hit them with the probe and got lucky. Sometimes luck is all you need
smiley1.gif
 
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