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Zaxxon repair

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Lurch666 View Drop Down
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    Posted: 06 Dec 2017 at 5:44pm
I'm repairing a sega Zaxxon that has a bad rom 2.
The eprom is a 2564 so I'm going to replace it with a rewired 2764 to see if it fixes the board.
I'm wondering if there's some sort of little pcb I can get to do this neatly as when I've built similar things before it's been a bit of a mess of wires.

If not what methods have you used to make such an adapter.

Sorry if this has been covered before but search aint working for this.


Edited by Lurch666 - 07 Dec 2017 at 1:39pm
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Lurch666 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Lurch666 Quote  Post ReplyReply Direct Link To This Post Posted: 07 Dec 2017 at 1:43pm
I decided to go ahead and make an adapter using veroboard to see how it went and it's fixed the bad rom2 problem.

the self test now passes all the tests (I haven't checked the sound yet).

But unfortunately the original problem still persists.
I first get the screen saying insert coin then it goes into demo mode but the ship flys to the top corner then the screen slowly fills with garbage (this is the part where it writes the ZAXXON title on the screen)

If I credit it up the game plays for a short while but with incorrect graphics flying across the screen then eventually it glitches out and lock up.

I'm thinking a memory problem but that's coming up OK in the self test.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Judder Quote  Post ReplyReply Direct Link To This Post Posted: 07 Dec 2017 at 5:02pm
Originally posted by Lurch666 Lurch666 wrote:

The eprom is a 2564 so I'm going to replace it with a rewired 2764 to see if it fixes the board.
I'm wondering if there's some sort of little pcb I can get to do this neatly as when I've built similar things before it's been a bit of a mess of wires.

If not what methods have you used to make such an adapter.

I think a few of us have made these before but getting a simple PCB fabricated by DirtyPCBs or similar is a good way to go and these various designs around you can base it around

Here's a very similar one for 2532 -> 2732 and vice verse

http://www.thedefenderproject.com/
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Lurch666 Quote  Post ReplyReply Direct Link To This Post Posted: 15 Dec 2017 at 8:16pm
just replaced one of the 2016 memory chips next to rom2 with a 6116 (it's equivalent) and the game is now running in demo mode properly.
Will now have wire up the rest of the adapter to test gameplay and sound.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Lurch666 Quote  Post ReplyReply Direct Link To This Post Posted: 7 hours 40 minutes ago at 8:20pm
Game played fine but without sound.
First I found that dip switch 1 number 7 has to be on for sound.
Then some sounds were missing but i remembered a thread I came across earlier:


Changed the caps and now board is fully fixed.
The adapter for the rom2 looks a bit ugly but can't be bothered to sort out a proper replacement.
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