Today I dumped another PLD from an Out Run PCB.Original device labeled ‘315-5228’ (@IC123 on VIDEO board) was a CK2605, I read it as PLS153 and then reduced the fusemap using the PLAD utility by Charles MacDonald.Lastly I recompiled the disassembled equations in a GAL16V8.
Got this ugly bootleg for a repair.
Game had no sound and the jump button didn’t work.
First of all, this bootleg is known to have the picture upside down and I wonder why the bootleggers left the game in this state.
Since I had no white noise from the amp I checked the circuit near it and found a capacitor with a leg desoldered. Unfortunately the hole was completely rusted and I had to run an ugly wire to another point on the pcb to restore the sound.
To do: find a thinner wire 🙂
For the “Jump” problem I traced back from pin 23 of the Jamma connector to input 2A of a 74LS257 multiplexer.
The jump button of the second player, was connected to input 2B of the same 74LS257.
So those buttons has the ouput 2Y of the 74LS257 in common, so to check if the TTLÂ was working correctly, I ran the input test with the second joystick and infact also the second player jump was not working. The output 2Y was oscillating but evidently not in a correct way.
Given that the game has no first player and second player playing at the same time, I opted with a simple but effective solution: I shorted 2A and 2Y togheter so that the first player button was connected directly to 2Y.
In this way when you press first player button you press also the second player one but for TNZS is not a big deal because you never play a co-op game 🙂
With this solution I could fix the game without bothering to replace the ttl chip
Game showed a static white screen at boot.
Checked the clock and it was fine, then I checked if the 68000 was reset correctly and found out that it didn’t get any reset signal.
Tracing back I came to a capacitor which had a leg unsoldered.
After fixing it, the game booted correctly
I started a game but I soon noticed that it the pcb played sometimes random or wrong music/sfx.
The game has no FM chip, so the OKIM6265 is responsible for music and sfx and there is only one soundrom.
Checking the circuit in detail I noticed one jumper for selecting 8Mbit rom was broken in half.
After resoldering a new one, the music and sfx was restored correctly.
Got this game for a repair.
Game booted without problems but it was missing music and sound effects.
The amplifier was working correctly as I could hear the typical white noise coming out of the speakers.
As you can see, the game is upside down and checking with Mame there is no flip dipswitch so unfortunately is one of the few horizontal arcade games which has the screen upside down (the other that I know is Athena from SNK).
Another thing you should have noticed is the copyright…..some smart italian arcade owner has hacked the original date from 1985 to 1987 to make the game looking newer….it’s unfortunately very common in Italy.
back to the real problem, I checked with my portable amplifier the input to the operational amplifier and there was no sound.
That meant that either the DAC was faulty of something in the sound circuit logic.
The DAC is a YM3014
The SD pin is the output of the YM2203 which is a digital waveform so normally you cannot check with an amp if the YM2203 is working or not.
The only thing you can hear is white noise but there is a trick:Â compare the breaks between melodies (example, between coin up and start game), so the YM2203 should also stop orstart again to output signals.
With this trick I could confirm that the DAC was faulty.
Replacing the YM3014 with a good one fixed the problem as expected.
I bought this faulty pcb from ebay at a very cheap price.
The seller mentioned that it had a “service switch error” and didn’t boot.
When I received it I could confirm the behaviour:
Several Taito games from late 80s to early 90s use a custom chip marked TC0220IOC which handles the inputs.
Looking at Final Blow schematics, the pinout is well documented so I started to check service signal which infact was always low on pin 36 of the custom chip
Before desoldering the custom chip, I checked the continuity of the Taito network resistor RRC4 (on Fighting hawk pcb) and I noticed that it had a very low resistance (less than 1Kohm)Â to +5V in comparison to the other pins which had a 10kohm resistance.
So, for what it costed I proceeded to desolder the network resistor and see if the pcb booted.
The game did boot infact and it was a good sign, meaning that the problem didn’t come from the custom chip.
I found the same network resistance on a scrap taito pcb and the service switch was fixed but unfortunately the airplane was going up and left all the time and fired and thew bombs continuously.
After running the test mode, I noticed that all P1 and some P2 inputs were triggered!
To end the story short, I had to exchange ALL the network resistances except one to fix the game.
Looks like the game was connected reversed at one point and the network resistances probably protected the custom chip.
No further problems shown up
