JuJu Densetsu repair log

Bought recently a faulty Toki PCB because I like this funny game (a bit underrated IMHO).For the uninitiated  it's a "run and gun" game developed and published in Japan by TAD Corporation in 1989.The board was in good condition :

But it played "blind", I could coin up and start a game but nothing was on the screen :

The RGB colors were inactive, stuck at LOW level :

They are generated by the custom 'UEC-51' (basically a DAC in SIL package like the Taito 'TC0070RGB') .

I have reproduced time ago this custom :

https://www.jammarcade.net/seibu-uec-51-reproduction/

Hence I know well how it works so I went to probe it and found that pin 10 was stuck HIGH :

This pin is the input for an /OE signal so it should have been active.I traced it back to an output of a 74S139 @7K  :

The logic comparator confirmed that outputs pins 11 and 12 were troublesome :

I piggybacked the chip with a good one and got displayed a correct image.At same time I found the board was actually JuJu Densetsu, the japanese release of Toki :

Obviously the chip failed the out-of-circuit testing :

The game seemed to play absolutely fine but, doing some comparison with online video, I found that some sound effects (like voices, jumps, etc)  were missing  :

These are generated by the OKI MSM595 ADPCM voice synthesis chip which plays samples taking and processing the data from an external ROM:

The EPROM was dumped fine, clock was present on the MSM6295 but all its address lines were stuck meaning the chip was dead.I replaced it and installed a spare:

All sound FXs were restored in this way.Board 100% fixed and an addictive game added to my collection!