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I've had three attempts at making and Earthbound Zero cart so far and unfortunately...None have worked!! My first copy came on and played music, but was scrambled... My question is on the wiring. I've run across two different methods of wiring. I'm looking for some advice on which is best. The first wiring, the one I got to come on a bit is this:

- Bend up pin 1, 2, 24 & 30 on PRG eprom
- Solder into place of the masked rom.
- Tie pins 1 & 32 together (+5)
- Tie pins 22 & 24 together
- Tie pin 2 & pin 24 hole together
- Tie pin 30 & pin 1 hole together

- Bend up pins 1, 2, 22, 24, 30 & 31 on CHR eprom
- Solder into place of the masked rom.
- Tie pins 1, 31 & 32 together (+5)
- Tie pin 30 & pin 1 hole together
- Tie pin 24 & pin 2 hole together
- Tie pin 2 & pin 24 hole together
- Tie pin 22 & pin 31 hole together

This came from a forum and I've seen it a couple places online. The second method comes straight from the NA ezine. It is a little different. I've tried it once and still nothing. It is as follows:

PRG wiring: bend up pins 1,2,24,30,31
Connect pin 2 to hole 24
connect pin 24 to pin 16
connect pin 30 to hole 1
pins 1 & 31 remain unconnected.

CHR wiring: bend up pins 1,2,22,24,30,31
connect pin 2 to hole 24
connect pin 22 to hole 31
connect pin 24 to hole 2
connect pin 30 to hole 1
pins 1 & 31 unconnected.

Any advice on which to use would be greatly appreciated. Thanks

It's hard to actually see the difference in what's going on here. And takes a lot of time to look up the datasheets and everything. So you might get a little more help or insight if you make it easier on us to see what exactly your doing. even pin names vice just numbers would help...

Bottom line, make the new memory match the pinout of the old one. You'll have a much easier time if you draw things out for yourself with a schematic vice just blindy following tables of what to connect where. Posting that may allow for more help as well.

It sounds like that one time you had sound working but had garbled graphics that you got the PRG side of the house working but had an issue with CHR. Not sure if that's valuable info for you or not.

Okay, will post pics of next attempt. Thank you

I was having similar problems that you are having now. What I believe the problem is that your iron is too hot. When I would solder at school, I noticed the games always worked fine. Then when I worked on it at home with my cheapy radioshack iron, they would not work at all. I think the temp was way to high and fried some gates on the chip.

lordloss wrote:I was having similar problems that you are having now. What I believe the problem is that your iron is too hot. When I would solder at school, I noticed the games always worked fine. Then when I worked on it at home with my cheapy radioshack iron, they would not work at all. I think the temp was way to high and fried some gates on the chip.

Possible but not very likely... I'd put money on that NOT being your problem. I would recommend drawing yourself a schematic of what pins don't connect to the pad below them. If you can't draw a schematic of what you're trying to do the chances of you getting the wiring wrong are HIGH. I would guess you're making the same mistake over and over again each time, but don't have a good way of realizing what your doing is wrong. DRAW IT!

I do think this is the reason. Part of my problem was that I was using OTP chips. I think these have a much lower tolerance to heat and burn out very easily. The wiring is very basic and I followed the same wiring scheme that worked for other boards and it seems the OTP chips have a higher failure rate.

Keep in mind that OTP EPROMs are probably very old. Who knows how long ago they got their UV charge. Windowed EPROMs are more likely to be in usable shape.

MottZilla wrote:Keep in mind that OTP EPROMs are probably very old. Who knows how long ago they got their UV charge. Windowed EPROMs are more likely to be in usable shape.

Yeah if the parts are bad I would say chances are it was bad before you touched the soldering iron to it. But I guess it doesn't really matter what the issue was if you've found the solution to be not using the OTPs.