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caius

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Some months ago I finally found a Bogey Manor PCB,I was after this board since ages.For the uninitiated Bogey Manor is an obscure game released from Technos in 1985 (but actualy running on Data East hardware), you can read more about here :

Bogey Manor review

The board was in quite good condition ( a little dusty though...) but marked as faulty
Bogey%20Manor%20PCB.jpg

Indeed, at first power up, it was completely dead, no sign of life.As always I do, I did a visual inspection of the board and found that the black SIL component marked 'RCDM-I4' was loose, almost detached from the board :
RCDM-I4.jpg

After a quck check on schematics of similar Data East hardware I realized that this part is responsible of main CPU RESET generation :
RCDM-I4_schematics.jpg

I managed to resolder the component to the PCB and board sprang to life :
board_working.jpg

Game was fully playable but sound was missing, I promptly pinpointed the fault to a missing amplifier (Fujitsu MB3730) in the sound section :

Missing_sound_amplifier.jpg

I installed the amplifier :

amplifier_fitted.jpg

This restored sound and fixed the board completely (screen upside is not an issue but a behaviour of the board as there is no dipswitch to flip it)


Happy of the result I decided to take a look at another board from Data East from my pile of faulty boards : Last Mission, a top-down multidirectional shooter released for the arcades in 1986.
The board was in fair condition :
Last%20Mission%20PCB.jpg

It booted up but background graphics were bad and sound FXs were missing, too :


From a quick check I figured out that the circuit that handles this part of graphics is located on top board so, for first, I dumped the ROMs and they were good.My attention was caught by the presence of some Fujitsu TTLs :

Fujitsu_TTL_top_board.jpg


Well all know they are very prone to failure and fail always in the same way with floating or stuck outputs.I went to probe them and, indeed, found the one @12B with a stuck output :

74LS283_12B_stuck_output.jpg


This was also confirmed by a scope (input signal on left, bad output on right of below picture)

74LS283_12B_analyzing.jpg

The IC failed when tested out of circuit :

74LS283_12B_failed.jpg

Replacing the IC restored the graphics completely:
graphics_fixed_jpg.jpg

The lack of soud FXs was pretty easy to troubleshoot.The sound effects are generated by a Yamaha YM2203 sound chip (while a YM3526 handle the music) and then routed to the serial data input of the YM3014 DAC :
sound_circuit.jpg

Checking this input with a scope revealed few activity :
soud_fx_signal.jpg

So, sure enough, I pulled the YM2203, installed a rounded socket and a good IC:
YM2203_reworking.jpg

This restored full sound and fixed board completely.Before archiving this yet another repair I noticed that Last Mission PCB used a similar black SIL component to the 'RCDM-I4' used on Bogey Manor, this was marked 'RCDM-I5' :
RCDM-I5_original.jpg

Looking at schematics, this part has same pinout of the 'RCDM-I4' but it's used for coin input hadling :

RCDM-I5%20(2).jpg


Anyway, I tried to swap the parts and they resulted perfectly interchangeable.Therefore, having a broken part, I thought it was nice to decap ad analyze this in order to have a replacement.The part was not really complicated inside so a reproduction was pretty easy and quick to do :

RCDM-I4_RCDM-I5_repro_real.jpg


Testing was successful on the freshly repaired Last Mission PCB :

 
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