In an attempt to help more people start using MAME’s fantastic ROMCMP utility I have made a simple GUI frontend for it.
Program can be found in the Downloads section under “PC Software”
Recently I’ve been working on some Windows based software to use the Data I/O 29 series programmers.
Its coming along well and I have a few people willing to test things out for me which has been great as its a pretty tedious task of trying things out and reporting back, rinse and repeat.
I captured a small video showing some progress.
The programmer itself isn’t all that hard to interface with as most of it is just issuing commands which are all outlined in the manual but there are a couple of things to deal with when it comes to uploading a file to the programmer.
I’ve also been collecting ID codes for programmers and modules so I can auto detect programmer and more importantly the module that is fitted. This allows me to auto populate a device list.
Ive tested this using a cheap USB to serial adapter and its been working fine.
These system boards from Namco has a common problem: SMD capacitors
These caps expecially the ones produced in the 90s are very unreliable and sooner or later will start to leak
On my boards there isn’t one that has the ESR in a good range.
On Namco system NA ( Emeraldia, Tinkle Pit, Super World Court) or NB ( Point Blank, Nebulas Ray), the problems you will face are sound related ( low sound or scratchy ), on ND system ( Namco Classic Collections), the SMD caps are used also for the RGB amplifier and in addition you will get colour problems.
I will take as an example a Namco Classic Collection I just finished to repair and which had all the problems coming in about one week of intensive use after a while in storage.
First of all it started to have trails on the RED component of the image.
The system uses a common RGB amplier LM1203 which for example is used on the majority monitors neckboards
Here are the usual circuit taken from the schematics of the LM1203:
As you can see , on the inputs of each colour component you have to place a 10uF cap.
Namco engineers decided to use a 4,7uF but I tested and there are no differences between the two values.
So, if you have colour quality problems on your Namco Classics Collection pcbs, first thing is to recap the RGB input section using commercial
electrolitic caps.
I am not a fan of brute force recap, so with my ESR meter I usually check all the caps and change only the ones that have a very out of range value.
As said before, after few days I get no sound for a while and after about 5 minutes, you could hear it coming up but very scratchy.
The amplifier got also really hot after a short time.
The system uses a LA4705 sound amplifier
I probed with the ESR meter all the caps and found out the both the small ones 2,2uF placed on IN1 and IN2 had a value of more than 99 ohms.
The other ones also were really not in the specification range but to get sound back it was enough to change the small ones.
As said the sound section of Namco system NA and NB is the same more or less, therefore if you start to have low sound and you don’t have an ESR meter,
change the 2,2uF, 47uF (33uF on the amp schematics) and 100uF one.
I got for my collection an untested boardset of Defender which was really in great conditions with no battery acid leak.
The boardset is the newer revision of Defender with the red label roms.
The game is very difficult to find it in working conditions nowadays because it has several weak points, expecially the 24 drams 4116 which are very unreliable to due the fact the run very hot and they require +5V, -5V and +12V to be applied at the same time, otherwise they will be damaged.
The old Williams PSU become defective and often they ruin the drams.
After converting it to Jamma and triple checked all the power supply lines I booted it up but the game appeared to be dead.
Fortunately Defender has a lot of bibliography and a very good manual which is also a troubleshooting guide.
I check the clock and it was working correctly, but after checking the reset line I saw it was pulled low all the time.
To make it short, Defender has two +12V power supplies, one regulated and one not.
You have to supply +12V also to the not regulated one because it is needed for the power on reset.
After adding that +12V t, the game booted but as soon as the message ALL UNIT OK was displayed it reset in a never ending loop.
I found out that the problem was caused by the ribbon cable , after reseating it a couple of times, the game booted correctly.
I started the game but the ship kept always going down.
With the test menu , it reported that the down direction was always pushed.
I checked the interface board which has the circuit for the inputs. the hex inverters 4049 were all toggling correctly, the pull up resistors were good therefore there was only one chip to check: the Peripheral Interface adapter 6821P.
I desoldered it and installed another one I had on stock taken from another arcade games.
Since I had no way to test it, I decided to put a 40 pin socket just to be sure I could easily swap it with another one in case it was defective.
Luckily the inputs were now correct, thefore I could declare the board fixed.
In the end I was very lucky because the game had only the input problem and no other issues.
A friend of mine sent this pcb to check why the background was all messed up
I immediately noticed in demo mode that all the characters fell down in an endless loop because they couldn’t walk on the platforms
After searching for the fault in the video board for some days, I decided to test all roms starting from the program ones.
Program rom 04 didn’t match with anything in Mame and after checking the pattern I saw it was full of garbage.
After reprogramming with a good dump, the game was restored perfectly.
It seems rom 04 has only the layout of all levels because even without its presence the game is booting
