Lethal weapon 3 - No DMD/MPU Fault

cathaldub

Member
Feb 22, 2015
30
5
8
Dublin, Ireland
Long time lurker, I’m looking for a bit of help if anyone could suggest any ideas here.
So I picked up this LW3 a few months ago, it didn’t boot at all, I recapped the PSU board and all my voltages are now spot on, game booting but no sound or DMD.
I downloaded Leon’s test Rom and powered up my MPU board with an external supply and narrowed down to 2 dead PIAs (9B and 7B), I socketed both of these and the game now boots, all sound working, but still no dmd, I done some testing on the DMD controller board and while waiting on some chips, I borrowed a known working dmd controller(thanks bigian) so now I get second of gibberish when I unplug the ribbon from the cpu board.
I noticed a small crack on the DMD so ordered a pinballsp colour dmd.
So I’ve installed it and I can now see the gibberish is the DMD Rom version. I’ve reburnt all roms, I’ve swapped the ribbon with one from my other pin, ive checked all traces from the PIA to the ribbon connector. The only thing suspect there seemed to be that some of the resistor networks(ra21,22,21)are reading a bit low.
My CPU Rom is the latest 2.08 and my Display Rom is also the latest 2.06
I’ve no idea where to go from here.
Here is a quick video
 
Last edited:
OP
OP
cathaldub

cathaldub

Member
Feb 22, 2015
30
5
8
Dublin, Ireland
It coins up and plays fine without display, I'll check the fuses again tomorrow, but I think i replaced all of them, definitely all them on the PSU board
Edit: I see this on pinwiki but it doesn’t have a diagram, I’ll stick the Leon Rom back in and get a reading on each cn22 pin, I didn’t know the Leon Rom output to that connector

 
Last edited:
OP
OP
cathaldub

cathaldub

Member
Feb 22, 2015
30
5
8
Dublin, Ireland
With the LEON rom installed I've tested the output of CN22

Pin 1 Ground
Pin 2 High
PIN 3-10 all pulse high/low
PIN 11-26 all high (I'm thinking these should also be pulsing? these are coming from PIA at 9B, I've ruled the chip out by swapping with another socketed PIA)
 

pinballmania

Site Supporter
Jul 21, 2011
1,740
979
113
Are you sure that the ribbon cables are correctly orientated. ie the red band on the cable between cpu and driver should go to pin 1 on each connector.

Could also be a faulty ribbon cable. Do you have one you can swap?
 
OP
OP
cathaldub

cathaldub

Member
Feb 22, 2015
30
5
8
Dublin, Ireland
Ribbons are definitely red stripe to pin 1 and I swapped it out from my other machine just to be sure.
The data lines 0-7 are coming from 5E(LS245), 5D(RAM 2064) so I'll try see whats going on there but I killed my logic probe last night :(
 
OP
OP
cathaldub

cathaldub

Member
Feb 22, 2015
30
5
8
Dublin, Ireland
Ok so I’m an idiot, while I socketed PIA 9b and 7b, the game then booted so I never retested it afterwards, all outputs on 9B are still stuck high, I’ve swapped PIA chips so I know it’s not the chip, not sure how I go about tracing back from here
 
Last edited: