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PGM repair - a few questions

VectorGlow

VectorGlow

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I've never repaired a PGM motherboard before (have repaired plenty of other board types though), now I have one with three carts in an unknown state.

Without a cart inserted the board produces a jingle, displays the PGM logo and enters the test menu.

I have three carts to test, all purchased 'as is' so basically in an unknown state.

- With 'cart A' inserted a momentary screen of garbage is displayed followed by the PGM logo then test menu. And that's it.

- carts 'B' and 'C' just boot to garbage, nothing else. Flipping the toggle switch achieves nothing (other than a blank display as expected), pressing the test button changes the screenful of garbage to a different screenful of garbage



There's no battery on the motherboard, no corrosion in that area either. Have thoroughly inspected both sides of the board for any badly corroded or broken tracks and all is well. Cart connectors are good, pins clean and straights.

Out of interest, is there perhaps a 'better' BIOS for test purposes? The label is missing from the BIOS EPROM but in the test menu the top right corner displays: V0001-001
 
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Can you open up the carts, if they are modified? Only converted carts for Ketsui and Espgaluda directly boot into the game, the rest should boot into the bios screen (jingle, logo).
At the point where it jumps into the test screen it should jump into the cartridge.

The BIOS should check if it can read the cartridge header, if it can't read it it jumps into the test menu.

Can you show a picture? The cartridge can override the BIOS font and graphic ROM, so if there is an error you'll see garbled data.

Also, if you have a scope, here is the cartridge pinout:
PGM Cartridge pinout
 
Thanks. Yeah, carts opened up, they are conversions. This type:

http://www.gc8tech.com/uncategorized/igs-pgm-ketsui-conversion-pcbs/

however, neither has the QFP 120-pin SMD chip in place, presumably they are using code that doesn't need it?

At the moment I'd just like to verify that the EPROM contents are good, already removed the 27C322 from the DDP DOJ and dumped it but not sure which binary to verify it against as I assume that there are different binaries for different cart types?

Thanks very much for the pinout, I'll take a look on my scope.

Can't easy post a pic of what I'm seeing on the screen I'm afraid, it's just garbage though from two carts (Ketsui and Espgaluda) while DDO DOJ only shows the PGM screen then test menu as if it's not even seeing the cart.
 
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VectorGlow said:
however, neither has the QFP 120-pin SMD chip in place, presumably they are using code that doesn't need it?
Click to expand...
Yes, the QFP SMD chip is actually not connected to anything, and was probably meant to throw off other people from cloning the design. :) (You could check continuity to the connector, not even power should be connected...)

They are custom boards. One problem with all conversions is that they are using 3.3V memory chips on a 5V system.

If you have a Mame rom set, the "bootleg conversion" sets should be what you need. I am not sure if Mame includes an unencrypted DDP3 ROM, but you could get my script for the custom boards to decrypt it.
 
Yeah. I couldn't see any tracks to/from the QFP so assumed it was nothing (unless it's a multi-layer board which it doesn't appear to be).

Thanks for the other info, I noticed the voltage regulator on each of the cart's PCBs.

The DDP DOJ bootleg supported by MAME is I assume this one:

2002.10.07 Black Ver., bootleg Knights of Valour Super Heroes conversion

So what would be the process to get that working, just use your script on it then program the binary to a 27C322 ? (where is that script BTW?).

Same applies to Ketsui and Espgaluda I guess?
 
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