Arkanoid bootleg bonanza

Fixed a PCB? Tell us how!
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Asure
Posts: 573
Joined: April 17th, 2013, 5:16 pm
Location: Netherlands
eBay: asure_nl

Arkanoid bootleg bonanza

Post by Asure »

Got a bunch of Arkanoid boots to test & repair where needed.

First up were some simple things, missing audio amp, missing audio pot etc. not much special. But the last board had some wierd issues.
The (NEC) Z80 was toasted, it had physical damage to the package, and looked like it had been really hot. Swapping this Z80 into a known-good board got me 'common ram error' so i set it aside.
With a working Z80, it fired up, but the bat was being drawn half way on screen, instead of at the bottom. Also some sprites in the intro animation were drawing at wrong places.

Comparing a working board, and poking around the rams, it appears the sprite ram is on the rightmost bottom (with jamma connector facing 'up'). Probing around sprite ram made the error worse, a few pins shorted and the bat was even 'higher' on the screen as before. Traced that back to a bunch of 74LS157 that controls part of the sprite area and 'where to draw' i guess.

Piggybacked a fresh pair of 157's onto the board, and all issues gone. Made a short video showing me doing all sorts of unhealthy chip pulling when the board runs :)

We start with a running board and one 157 replaced fixing the sprites, but the second 157 is still piggybacked on the board. Halfway thru i take it off, and the bat is drawn in the middle of the screen again :)



And here's a picture with the two new replacements on the board:

Image

Now i just need to score a C1182(H) amp, volume pot, and new Z80 to fix the last of the five boots i got and then all will be well :)
The board has double-holed area so it can take a C1182H and C1182 as well.
Note to self:

C1182H = NTE Equivalent NTE1286
C1182 = NTE Equivalent NTE1285
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