We had two separate files for M92-b-2l.
One was just labelled for M92 hardware and the other was for Ninja Baseball Batman.
I deleted the entry for M92 as the Ninja Baseball Batman dump was from an actual unlocked PAL chip.
End user will not notice any difference, this update is to keep a record of what has been done and when.
Today I dumped the two specific PALs from an Undercover Cops (IREM M92 hardware).The two devices (PAL16L8) are located on ROM board (M92-E-B) , both dumps have been tested working in a GAL16V8 targeting device.I also succesfully tested the three PALs dumps already on our database (labeled as ‘M92-A-3M’, ‘M92-A-7J’ and ‘M92-A-9-J’ on CPU board), this confirms they should be the same for all M92 games.
Got 2 more PAL dumps from the M92 range, this time from a Hook PCB.
We are not sure if the ROM board PALs are game specific so they are listed under the general M92 header.
Thanks to caius and robotype for these PAL dumps
Zab has dumped the PALs from an M92 board, Gunforce.
They are all in GAL16V8 format and have been tested.
Thanks once again to Zab for his contributions
Got this Vigilante PCB (by Irem) in a trade some years ago:
Board was dead, stuck on a purple static screen:
As usually I started my troubleshooting with a visual inspection and noticed severe corrosion in some areas, especially around the 3.579545 MHz oscillator:
Analyzying the main Z80 CPU revealed no clock on pin 6.This signal was present on oscillator output but then was lost when routed to the inverter (a 74LS04 @IC30) :
Replacing the TTL restored clock on Z80 but board was still dead.Probing the /RESET pin 26 with an logic analyzer showed an unhealthy signal, there was no proper transition from LOW to HIGH but only some oscillations :
/RESET signal is generated by the MB3771 voltage monitor @IC31.I promptly replaced it:
In this way proper signal was restored:
But main Z80 was still inactive, data/address busses were silent as well as control lines.This lead me to think the CPU was faulty so I removed it:
Testing it in another board confirmed it was really bad.With a good CPU the board finally booted up but the sprites were mostly absent, I could see only some parts of them randomly flying over the screen:
After some time spent to check different things I pinpointed the fault in a bad interconnect ribbon cable.For safety I replaced both of them:
Board fully working again and a quite enjoyable game added to my collection.
The repair was accomplished but, as always I do, I visually inspected the board looking for some candidate parts for a reproduction and I spotted two possible ones.The first is marked ‘8M472J221J’ (‘RGLD8M472J221J’ on manual parts list)
It’s nothing more than a custom resistor network used for inputs, you can find it also on other Irem hardware like M72, M92 and M107.Here’s snippet from R-Type schematics:
I reproduced it this way :
The latter, marked ’10L471G’ (‘RGSD10L471G’ on manual parts list) is interesting since it’s a R2R resistor ladder used to convert to analog the 5 palette digital bits outputted by the surface mounted ‘KNA91H014’ custom.You will find always three of them (one for each RGB color) coupled to one custom.
Its implementation on schematics:
From my experience and other references too the original part is not really reliable (it will crack or burn) so I reproduced it as well:
Testing both reproductions on the repaired Vigilante PCB: