ReproductionsComments Off on Konami ‘083’ reproduction
Jul262019
This is another ‘poor man’s’ custom IC reproduction I made with no use of CPLD or other complex programmable logics.The part reproduced is the Konami ‘083’, a 28 pin 600mil in DIP package which most of times comes with scratched-off part name :
It can be found on several Konami PCBs, you can refer to this useful spreadsheet (credits to ‘mattosborn’ on KLOV forums)
Received for repair from New Zealand an original Bubble Bobble PCB.Set is made of a CPU board
And a VIDEO board:
It came already adapted to JAMMA so it was just matter to plug it in.I did it but nothing came up on screen. I noticed wires were soldered onto the pins of ‘H’ connector and then a molex connector was used to carry power to JAMMA fingerboard:
I didn’t like this solution because it can cause loose connection so I removed the molex connector and soldered wires directly to JAMMA fingerboard.In this way the board properly booted up, games was perfectly playable with sound too but every alternate horizontal line of graphics was missing :
From top of my experience I know this kind of issue are most of times caused by bad counters (74LS161/163/169).Looking at board I spotted two rows of 74LS169 on bottom VIDEO board:
From schematics I could see they are involved in VIDEO RAM data bus, this made sense :
I went to probe these 74LS169 in circuit with my HP10529A logic comparator, all of them passed the test except the one @IC64 that gave troubles on all its outputs:
I pulled the part out :
It failed the out-of-circuit test on my BK560 :
I installed socket and a fresh IC :
This cured the issue and fixed board completely.End of job.
PCB Repair LogsComments Off on Space Invaders DX double repair log
Jul262019
I received from Portugal a couple of Space Invades DX PCBs, a game released in 1994 by Taito (more or less a port of the original Space Invaders, with a few new features).
Both boards were in very good condition but completely dead.Here’s the first one:
All I got on power up was a steady black screen.Probing the 68000 main CPU revealed the address/data busses were active but the three interrupts inputs (IPL0-IPL1-IPL2) were all in fixed high logical state.I traced these inputs back to a PALCE20V8 marked ‘D72-07’ :
Then I disassembled the fusemap of the MAME dump of this PAL being able to identify its inputs and outputs:
/** Outputs **/
Pin 15 = o15; /**(Combinatorial, No output feedback, Active low) **/
Pin 16 = o16; /**(Combinatorial, Output feedback output, Active low) **/
Pin 18 = o18; /**(Combinatorial, Output feedback output, Active low) **/
Pin 19 = o19; /**(Combinatorial, Output feedback output, Active low) **/
Pin 20 = o20; /**(Combinatorial, Output feedback output, Active low) **/
Pin 21 = o21; /**(Combinatorial, Output feedback output, Active low) **/
Pin 22 = o22; /**(Combinatorial, No output feedback, Active high) **/
Pin 20-21-22 were outputs to 68000 interrupts lines and they were confirmed to be stuck high along with all other outputs :
Although PAL was secured I tried to read it in my programmer, this would have at least told me the state of ‘health’ of the chip.Reading failed hence the chip was faulty:
I burned a GAL20V8 (GAL and PALCE are most of time interchangeable) with MAME fusemap :
Board booted up with no further issue.First board repaired.
The second board:
As said, it was completely dead.Probing the 68000 main CPU revealed the clock input was stuch high:
I traced it back to a 74F161 @IC51 which acts as a clock divider of the 32Mhz signal generated by the near oscillator :
There was nothing coming from the oscillator into the clock input (pin 2) of this 74F161 counter:
At first glance I thought the oscillator was dead but before replacing it I made a visual inspection on solder side.I found a dry joint on its output pin :
I promptly reflowed it and then powered up the board again.It booted up with no further issues.Double repair accomplished.
The ‘CUS99′ (simply silkscreened ’99’) is a custom IC used on Namco arcade PCBs.It’s a 16 pin SIL component covered with a brownish coating :
It can be found on pre-System86 (Pac-land, Sky Kid, Gaplus, Dragon Buster and other boards..), System86 (Rolling Thunder and other games on same PCB layout) and System 1 hardware.From the scarce info about it the ‘CUS99’ is involved in sound volume control but we knew nothing more detailed about, pinout from official schematics apart :
Recently I’ve been sent by the user ‘JorgePT’ a pile of System 1 boards for repair hence, with his permission, I analyzed the part. After drawing schematics of its internal structure I came to the conclusion that the ‘CUS99’ is nothing more than a 4-bit DAC with output level control performed by analog switches.Its design was quite simple and easy to reproduce with few parts :
Testing of the repro on a Pac-Land PCB was successful:
It’s a 40 pin custom IC on the TOP board of the kung Fu Master stack, sitting at E1 & E2 between two rams and the colour proms
This most likely deals one deals with the final image processing, like layer priorities, just before outputting data into the colour proms
I used a bootleg to see how this one was reverse engineered by bootlegers at the time and identified and area between the rams and the colour proms.
Tracing multimeter confirmed those 9 LSxx ICs were indeed connected to the same ICS as the custom. So I fired up easyEDA and got busy .
A few days later, voila! a working IC and a working board. Not a complicated thing to do, it just takes time to trace back everything .
Huge thanks to Caius for his recent inspiring work on making repros for a lot of these custom ICs and has prompted me to look into the topic and start making my own too. The more the better !
And as usual, for those who prefer the video format :
