My reproduction work continues with a new chapter.This time I took into account the custom IC used on some Toaplan/Taito PCBs.Silkscreening under it says 'GXL-01' :
But you can find it with different labels.On Wardner/Pyros it's 'WT1' :
'T.T.1' on Twin Cobra/Kyuukyoku Tiger :
'L-01' on Sky Shark/Hi Sho Zame :
The IC is a DIP42 .600 mil package and it accomplishes graphical functions generating the backgrounds.First of all I identified the pinout and external connections with the board.Then I thought about different designs of the equivalent circuit also studying how same functions were achieved in previous hardware.Lastly I came to a replacement board with same dimensions of original IC :
The "smoke test" was successful, the replacement worked on all boards I could try. On Wardner/Pyros :
Received some days ago a bunch of faulty boards for repair.There was an original Toki in very good condition :
The board booted into game and was playbale with sound too but sprites were wrong :
As always I started my troubleshooting with a visual inspection and noticed that a couple of 74LS273 TTLs were replaced and sockets installed :
The work had not been done properly because some traces were broken and then patched with jumper wire on solder side :
I opted for redoing the job starting to remove the previously installed sockets :
This revealed some pads/traces were destroyed as well as some rivets ripped off from the holes.After checked all connections and rebuilt the traces I reinstalled the ICs on round machine sockets :
This lead to some improvement but the sprites had still wrong colors :
I focused on the reworked area :
Probing around I found that shorting some pins of the 'SIS6091' surface mounted custom ICs restored correct colors.I also figured out that these pins are in common between all four 'SIS6091' (probably a share bus) but I found that one pin was not.I carefully inspected the solder side of the board at the affected area and after some time I noticed a strange break in one trace.The microscope and a check with multimeter confimed that trace was really broken (it seems to me from factory more than accidentally)
I promty patched the trace, this restored corret sprites :
I played some games with no other issue found so I could successfully close this repair.
Here's another reproduction of a custom IC I made recently.The part in question is used on Namco PCBs and comes in a DIP28 600 mil package with stamped number of '07XX' (but the 3rd
and 4th digits can vary because they actually refers to the lot/date
production hence the first two digits really matters)
Technically
speaking it's a clock divider, specifically it that generates the horizontal and vertical video timing signals divided from the master clock.I made my own implementation with simple thru-hole TTL gates :
I succesfully tested my design on a Galaga PCB :
This open the way to a future implementation of this custom IC onto a CPLD or FPGA (already done by someone else though).
Some days ago I received for repair an original Salamander PCB.The two stack set was in good shape in both CPU and VIDEO board :
The board was not booting and kept resetting meaning watchdog was active :
The video board was marked by owner as good hence I focused on the CPU board./HALT line of 68000 main CPU was stuck low meaning it was stopped :
Board was heavily populated with Fujitsu TTLs and we are all aware about poor reliability of these parts.They usually fail showing floating outptus and this is what I experienced while checking them, my probe was not detecting any logic level on some (all 74LS244, a bad lot perhaps?)
A good rule when you encounter Fujitsu TTLs would be to replace them all because they sooner or later fail.In this case I started to pull out the suspicious ones, three of them were really bad :
After replaced them the board finally got past the POST and entered in game but while testing I noticed that a music track and some sound FXs were missing :
Checking with an audio probe revealed music and sound FXs were fully generated but then they didn't reach the inputs of the amplifer.Iscratched my head to figure out this and after some time I remembered that this board has stereo sound and, like in other Konami games, you must close a jumper (the 'CN2' MONO or the 'CN3' STEREO one) in order to hear both channels :
This is what I did giving full glory back to this great game!
P.S.
You can read more about Konami stereo sound in this post by my mate Yves:
Another reproduction of a custom IC, or better, this is a 3-in-1 replacement of the Namco MCUs marked '60A1', '63A1' and '64A1'.
They are mostly the same part with identical package (DIP40) and pinout but they are not interchangeable.
'60A1' found on Pac-Land, Dragon Buster, Sky Kid (all revisions except early one), Sky Kid Deluxe, Alien Sector, Baraduke, Metrocross, Rolling Thunder and all other System86 games.
'63A1' found on first revision of Sky Kid.
'64A1' found on all System 1 games (Splatterhouse, Galaga88, Pac-Mania, etc)
Needless to say the original part is very prone to failure (especially the '64A1')
My replacement covers all three MCUs, you can simply select the desidered one via a dipswitch:
Here's testing of the replacement on different boards :
'60A1' on Rolling Thunder :
'63A1' on Sky Kid (first revision)
'64A1' on Splatterhouse :
A special thank to my friend 'uchopon' for helping me to achieve this result.
