RGB-Pi JAMMA adapter repair

This RGB-Pi Jamma adapter with raspberry pi 3+ was completely dead. There's a helpful repair wiki that suggested it was most likely one or both of the I/O controller chips MCP23017 causing the issue.

This is because when the adapter is plugged in upside down it sends 12v where 12v should not be and frys the chips. Checking with a multi meter player 2 button 2 was reading open.

I had to order the very tiny chips from mouser and wait a week for them to arrive.

The Pi faces down, so no wonder these get plugged in upside down.

 

 Bad chip removed and new one fitted.

 

 

I had to dust off the hot air station for this repair as the chip has a ground pad on the bottom of it, making it impossible to remove with just a soldering iron.

 

Repair complete.

WWF Wrestlefest repair

This WWF Wrestlefest board worked fine apart from vertical lines across the screen.

I went down the rabbit hole with this one first thinking it was most likely one of the surface mount custom chips as there isn't too much else on these boards. I fixed a couple of loose pins and took off the TJ-003 custom chip as it was so badly fitted at the factory that the top row of pins were almost touching the wrong pads by less than 1mm.

This made no difference though, I then went on to use a couple of different community made test roms that test the rams but these all passed. The problem with these test roms is they tell you they're testing background / sprite etc rams but not the locations and more importantly the ones they don't check.

Turns out they don't check IC24, 26 and 27, I guess as they don't have direct access to them from the cpu and as these were the main rams I suspected of being faulty I decided to just remove and test them.

Luckily the first one I removed (IC24) turned out to be the bad one, a standard 6116 skinny type. I fitted a socket and a new old stock ram and it's back up and running as noraml.

 

Bad Ram

 

New ram fitted and TJ-003 cleaned up

 

 

 

 

Repair complete.

Virtual Boy Blockbuster case foam replacement

I am not sure how many people in Europe own a Virtual Boy let alone a Virtual Boy in a Blockbuster rental case. But if such a person does exist they'll most likely need to replace the foam in their case. As the original foam disintegrates over time and makes a nasty mess every time you open the case. A good precut replacement is available from an american seller but it's over $100 before shipping.

So I went looking for another option, turns out there's a listing on amazon with the perfect sized pre-cut foam. I bought two 50mm sheets and glued them together with spray glue, this was to give me the option of having some stuff raised so it's not all at the very bottom of the case and it keeps it very close height to the original foam.

 Here's how it turned out.

 

I still need to replace the top part and I put a layer on the bottom so the larger parts like the headset and controller aren't directly touching the bottom of the case, for this I used some of these foam sheets from aliexpress.

How to repair a Naomi cartridge with bad maskrom(s)

First you'll need to be able to flash tsop56 S29GL128 chips, I sourced the chips from aliexpress but mouser also has them. Then you'll need to order some flex pcbs from osh park, pcbway etc using the attached gerber files.

This repair will require a microscope or a magnifying glass and some soldering skills. Lots of flux helps.

I've had a King of Route 66 naomi 2 cart for a while that I wanted to repair but it had two bad maskroms and there's no equivalent flash chips. The S29GL128N is close but it's 56 pin instead of 48 so this is why we need the adapter flex pcb in between the chip and the board.

I had osh park make me some as they were cheaper than china for a small run. As you can see I've added vias (holes) to the pads you solder to the board, this makes it easier to get a good connection as you can flow the solder through the hole and heat both pads at the same time. The only problem with this is, osh park wasn't able to make the holes that small so they are too big and split the pads. They still work fine though so I still recommend this version. I have added gerbers with with no vias too though to give the extra option.

Next to remove the bad maskroms and replace them with flex pcbs.

 

Then once that is done solder the preflashed replacement chips on top.

 

 

Then do a rom test to confirm every pin is soldered correctly.

 

 

 Download gerbers here.

054573 and 054574 reproductions

I have quite a few Konami boards building up in my collection with either missing or not working 054573 / 054574 customs. So the time had come to finally make up some repros. These tiny boards are used in the video output of the following games.

Bucky 'o Hare
Cow Boys of Moo Mesa
Gaiapolis
Martial Champion
Monster Maulers
Mystic Warriors
Violent Storm
Xexex

They're basically a single layer pcb with a bunch of tiny components and printed resistors directly on the board, including ones hidden under the 74LS07, very sneaky konami. :)

 

After getting the epoxy and components off I was able to draw the schematics in photoshop.

Then create gerbers in kicad and get pcbway to make me up some prototypes.

 

I copied the originals 1:1 or as close as I could, I had to move some of the resistors from under the LS07. You can download the gerbers here along with all the infomation you need to make your own.

Replacing Naomi 1 and 2 case fan.

A quick guide for replacing Naomi 1/2 motherboard case fans. You'll need a Gelid Silent 6 60mm x 15mm fan, a soldering iron, wire strippers / cutters and some tape or heat shrink sleeving.

First desolder or cut the wires from the original fan as you'll want to reuse the original cable.

The new fan is almost perfect apart from the cable that has all black wires, this means you have to be careful to wire it up correctly.

The top wire is ground, the second middle wire is 12v and the bottom wire is sense that can be ignored. Cut ground first and leave about 2 cm of wire from the fan. Solder it to the old cable.

Do the same again for the 12v red wire.

Cover the exposed solder with tape or heat shrink sleeving.

Fit the fan as shown so it blows hot air out of the case.

Finally put the cable back into the filter board and you're done.

Naomi repairs - Stuck inputs and Error 4

I had a lot of six Naomi motherboards in for repair recently, mostly just replacing rams so nothing worth logging but one of them was interesting. It would boot but would not enter test and the dip settings were stuck on, I traced the dip switch traces to the other side of the board. To a Sega custom chip 315-6146, I decided to replace the ram connected to it first as that is was much easier to swap and thankfully it was just the ram, a common 62256 type.

While playing with Naomi stuff I found that the Net Dimm board that I have owned and used for a good 15+ years was slightly faulty. It wouldn't return a serial number, this isn't usually a problem apparently because I haven't noticed an issue before, not until I tried to load Ikaruga and got error 4 that is.

A google search brought up the exact issue, serial number not returned by Dimm board but not many people with the issue, I only found one forum post with someone else with the error. It doesn't look like they ever fixed it either.

The serial number is stored on a tiny EEPROM on the bottom of the Dimm board at IC6S

 

I took a replacement from a scrap board but a new 93C46A EEPROM programmed with the dump from mame would have also worked.

That got her going.