GeneralComments Off on Jaleco ‘JK-03’ reproduction successfully tested
Dec312018
Some time ago I made a reproduction of the Jaleco ‘JK-03’ custom SIL used for inputs handling on some Mega System 1 PCBs but at that time I was not able to test it due to the lack of a proper PCB hence I asked for some volunteers.You can read the post here:
Today I can report the reproduction is fully working thanks to the test carried out from the user ‘Astro X’ of AP forums on his Saint Dragon PCB with missing ‘JK-03’ (actually an hack was installed as workaround) :
I received for repair a quite rare original Spelunker PCB (on Irem M62 hardware).Board is a three stack one made of a top board (which carries most of sound hardware) :
SOUND board
A middle CPU board (specific for each M62 game) :
CPU board
And a bottom VIDEO board :
VIDEO board
The PCB had severe GFX faults, the sprites were only lines vertically stretched all over the screen:
All the sprites circuit lies on bottom VIDEO board which is the same for all games that run on M62 hardware.Looking at Kung-Fu Master schematics I could figure out that data bits from sprite ROMs are fed into the custom marked ‘KNA6034201’ :
Custom ‘KNA6034201’ in DIP40 packageCustom ‘KNA6034201’ schematics
The inputs were all active but most of outputs floating:
So the custom was most likely internally faulty.Luckily I have done a reproduction of this component some time ago.You can think of it like a 24-bit parallel to serial shift register:
I removed the custom and installed the reproduction:
‘KNA6034201’ repro
The sprites were back but not perfectly as they were lacking of lines and misplaced too:
Sprites not yet perfect…
The sprite line buffer consists in two 2k x 8-bit static RAMs (Toshiba TMM2018 used here) :
Sprite line buffer
Probing them revealed on both a floating address line (pin 1, A7) :
Address lines are generated by the surface mounted custom ‘KNA6074601’ :
Custom ‘KNA6074601’
Its pinout/implementation from Kung-Fu Master schematics :
I had no other choice than replacing this part so I asked the owner to look for a donor board.He found and sent me a Vigilante PCB which carried the ‘KNA6074601’ on bottom board :
Vigilante donor board
I removed the faulty one and soldered the spare back :
Got from Portugal this Out Zone PCB, actually a low-budget korean version :
At visual inspection the board lacked of two 6116 SRAMs (but sockets were installed)
After fitting them I powered the board up and I got the usual black/white wavy striped screen but no boot into game, 68000 main CPU got stalled right after :
Multiple could be the reasons, in particular this Toplan hardware requires the sound circuit to be running otherwise the whole system can’t be initialized.A Z80A rules the sound system :
Z80A audio CPU
When I did piggybacking on it I got a ‘SUB CPU ERROR’ message on screen :
Once removed the IC I had confirm that it was really bad.With a good Z80 the board successfully booted into game but sprites were all blocky (it seems this is a common issue of this hardware…)
Sprites data are stored in four 1Mbit 28 pin MASK ROMs :
Sprite MASK ROMs
Devices were soldered in on my board and not socketed like usual so I was forced to remove all of them for dumping.Two of them gave different CRCs at each reading :
Specifically the ones marked ‘ROM1’ @1B and ‘ROM4’ @1L :
Faulty 1Mbit 28 pin MASK ROMs
I replaced them with two 32 pin 1Mbit non-JEDEC EPROM devices.All seemed fine but while playing the game I noticed some sprites (like explosions) had lines through :
Looking at hardware I figured out that the sprite line buffer is made of four 6116 (2k x 8-bit) static RAMs:
Probing them with a scope revealed some dead outputs of the one @12L :
On the right no activity on some data lines of 6116 SRAM @12L Good signals on the left for comparison
The chip failed the out-of-circuit testing:
Installing a good RAM chip finished the job.Repair accomplished.
The ‘UEC-01’ and ‘UEC-02’ are two custom ICs you can find on most Seibu/TAD Corporation PCBs also marked as ‘HB-1’ and ‘HB-2’.They are ceramic modules in SIL/SIP package.Here’s how they looks like:
The first handles I/O, the latter drives coin counters/lockouts.Reproducing them was straightforward given the simplicity of their internal circuit so for sake of completeness I took into account also the ‘UEC-02’ although nowadays few people use coin counters:
Testing on a Blood Bros PCB :
The ‘JK-03’ can be found, instead, on Jaleco MegaSystem1 hardware, it accomplishes the same function of the ‘UEC-01/HB-1’ handling the inputs.It comes in form of a SIL/SIP ceramic module as well (with different pin counting and pitch though)
Having no part to analyze I used some available schematics in order to reproduce it:
Due to the lack of a working PCB I could not test it hence volunteers are welcome!
