DoDonPachi DaiOuJou conversion graphical glitches

[nassekova]

I bought all three conversion from sheep_nova and they worked just fine in the beginning. But now my ddp has developed some kind of graphical glitch

I have cleaned all the contacts with IPA and I have the better version of IGS PGM which has contacts on both sides.

Tried to reflow some of the traces that were pressed by the plastic inlay inside the cartridge, but no luck. I even changed the EEPROM to some MAME ddp one, but since I don't know what version rest of the chips are, it did not even boot to the game.

Any clues what could be the reason?

Game works just fine, but graphics glitch

 

[nassekova]

Found the right MAME file and burnt new EPROM. Problem still remains

Any ideas? Could it be the bottom cart or do you guys think that the problem is on the same cart which has EPROM on it?

 

[rewrite]

Visual inspection is probably your greatest tool at this point. Start looking for dodgy solder joints or wires. Try carefully pushing down on some of the chips while it's running to see if you can get the glitches to clear up.

Fortunately/unfortunately most people moved on to fluffy's carts for these, so there are fewer folks able to look at theirs to help you :/

 

[nassekova]

I asked if @sheep_nova had any clue what could be the issue. Super nice guy as he is, he contacted his guy who makes these and came with a possible culprit: bottom boards 3,3v cable (or that's what I assume it is) that goes to all 4 chips there.

And behold! Old cable was pretty thin and it was peeled with just melting the plastic shell with soldering iron and thus had lot of plastic mixed with the tin.

So I took the old cable off and cleaned the board

Added some more beefy cable there

And now it works as it should

 

[bagheera369]

Nice...probably what's happened with my ketsui cart. Will crack it open, and check that out.

 

[XtraSmiley]

Thanks for the tip. I bought all three from a member here who got them from SheepNova and the DDP had similar graphical problems on one of the two PGM mother boards. I have no idea why it does this on one motherboard but not the other, but I'll crack open when I have time and see if it's the same issue.

 

[caius]

Sadly this conversion will last few time because it's poorly engineered.There is no voltage regulator to supply 3-3.3V to the Flash ROMs but only a couple of diodes which create a simple voltage drop.Plus and most important thing, all the busses/control lines of the FLASH ROMs are still receiving +5V TTL signals hence sooner or later they will go bad.

 

[XtraSmiley]

Sadly this conversion will last few time because it's poorly engineered.There is no voltage regulator to supply 3-3.3V to the Flash ROMs but only a couple of diodes which create a simple voltage drop.Plus and most important thing, all the busses/control lines of the FLASH ROMs are still receiving +5V TTL signals hence sooner or later they will go bad.

Is there an easy fix?

 

[caius]

For supply 3-3.3V to the Flash ROMs you can simply use a LDO voltage regulator in place of the diodes.But for proper logic level conversion of bus signals you need level shifting, this means re-engineering the whole board so not easy doable.

 

[RandomRetro]

Thanks for the post @nassekova. Have a graphics issue on my DDP DOJ cart from Sheep too. Looks like it might be caused by the same wiring. Will swap it out and test.

 

[XtraSmiley]

For supply 3-3.3V to the Flash ROMs you can simply use a LDO voltage regulator in place of the diodes.But for proper logic level conversion of bus signals you need level shifting, this means re-engineering the whole board so not easy doable.

Thank you for the info.

Hmm, I wish I knew about this before. Anyone else that has these Sheep carts worried about this?

Should be let him know so he can stop doing them this way?

Does the thread about cart conversion address this?

 

[twistedsymphony]

Does the thread about cart conversion address this?

yes, probably 1/3rd of the discussion is related to this exact topic, including guides for installing regulators. it has been discussed to death.

This is a big reason that the Fluffy PCBs exist, since they don't use the low voltage ROMs they don't need level shifters and there's no risk of early failure.

Interestingly some of the original PGM carts are setup for low-voltage ROMs already, my DDP DOJ conversion cart has 3.3V converters and level shifters as they were part of the original cart design.

 

[XtraSmiley]

Does the thread about cart conversion address this?

yes, probably 1/3rd of the discussion is related to this exact topic, including guides for installing regulators. it has been discussed to death.
This is a big reason that the Fluffy PCBs exist, since they don't use the low voltage ROMs they don't need level shifters and there's no risk of early failure.

Interestingly some of the original PGM carts are setup for low-voltage ROMs already, my DDP DOJ conversion cart has 3.3V converters and level shifters as they were part of the original cart design.

Thanks, makes sense, I just wasn't following that thread, it's so long!

So is there a way to fix these and what's the real risk? Like years later poof, or months? Weeks?

 

[twistedsymphony]

So is there a way to fix these and what's the real risk? Like years later poof, or months? Weeks?

I personally believe the risk is overblown. While levelshifters for the address and data lines is the "right way" to do it, leaving them connected to 5V sources is still within the tolerance range of most of the ROM chips used here. As for the power pins the use of diodes or resistors to do the voltage drop is a bit more risky, swapping to a regulator costs less than $1 and is about 5 minutes worth of work so it's worth doing IMO, but there's a good chance that you'd never see any negative effects from just leaving the diode or resistor hack in place.

 

[XtraSmiley]

So is there a way to fix these and what's the real risk? Like years later poof, or months? Weeks?

I personally believe the risk is overblown. While levelshifters for the address and data lines is the "right way" to do it, leaving them connected to 5V sources is still within the tolerance range of most of the ROM chips used here. As for the power pins the use of diodes or resistors to do the voltage drop is a bit more risky, swapping to a regulator costs less than $1 and is about 5 minutes worth of work so it's worth doing IMO, but there's a good chance that you'd never see any negative effects from just leaving the diode or resistor hack in place.

Sounds good, I'll look into this when I get some time (when oh when will that be!).

In the meantime, @sheep_nova please look at this post and update your conversion method! For under a $1, you would be selling a better product it sounds like and I LOVE referring people to you for items from China, so please keep up the good work and don't swerve into territory of some worse sellers!

 

[twistedsymphony]

If you're interested here is the conversion cart I made myself with the proper voltage regulator and capacitor setup:


And here is the KoV2 original cart setup for 3.3V with built in regulator and level shifters:
Any PGM Conversion info out there?


and HERE is my review the SheepNova and Lydz conversion carts where I recommended adding 3.3V regulators a year an a half ago
Any PGM Conversion info out there?

 

[Flinnster]

Damn.
My DDP-DOJ-BL cart has given me horizontal dark lines through level backgrounds and the logo and title screens for as long as I can remember.

And now I read about the kynar wire links to the chips on the base board.... my cart definitely has the very same, with the dual diode chain at one end.

I'm quite shocked at the thickness of the wire you've been replacing it with, what guage is that?!
Hmm... could I run another set of kynar alongside the existing I wonder..

Also, if there are vias next to all those pin legs, why not just solder to the vias?

 

[nassekova]

I'm quite shocked at the thickness of the wire you've been replacing it with, what guage is that?!
Hmm... could I run another set of kynar alongside the existing I wonder..

Also, if there are vias next to all those pin legs, why not just solder to the vias?

I just took the "thinnest normal wire" I had and used it instead of kynar. Probably works with kynar too if you just solder it better and make sure there is no melted plastic mixed in the solder etc.

I think not all those vias were connected.