Now that i know the sound rom is faulty i put it in my programmer to read it,surprisingly it did read but when i did a romident it was not reconised.Ok now i burned a new one using a 27c512 with the correct data,fired it up but still no sound
.
Checked the z80a on pins 15 and 16 but now they are high only,decided that the z80a must be bad so i removed it and put in a socket and a good working z80a.
Fired it up but still no sound,scoped pin 15 and 16 on the z80a and it was now active which was a good sign.Next i scoped the 64k sram (ic30) which is located above the sound rom,scoped all outputs and i found that outputs at pin 15 and 16 showed up bad signals.Removed the ram and put in a new socket and ram.
Fired it up and................😭 still no sound,scoped the sram and all outputs looked ok,next i scoped the yamaha sound
generators analogue outputs pins 18,19 and 20 above the sram and showed no signal (dead outputs).
Luckily this was already socketed,put in a new one and fired it up.........................................🤞
ohhh yes music to my ears,finally got the sound working.heres a pic of the parts i have removed.
Now that the game has its graphics back and sound the last fault to tackle is where when you credit and start the game
the plane goes up on its own and keeps bombing.
Ok while the game was running i checked all the player 1 and player 2 inputs at the jamma edge connector.
Normally they should be pulled up to +5v and they were except pin 18(player 1 up) and pin 23(player1 bomb),
my meter checked out as +2.4v which is low?followed all these inputs and they got to 4 resistor arrays,inputs for up and bomb goes to rc1 and rc2.Measured the internal resistors which are 100 ohms and checked out ok so this got me thinking
that the custom chip (TC0220IOC) might be bad.What i did was to remove these two resistor arrays from the pcb and powered on and the inputs to the resistor array went to +5v which is good but output from the array was +2.4v so unfortunately the custom chip is bad.
ahhhhhhhhhhhhhhhhhh i hate custom chips 🤬,heres a picture of the chip.
Its possible that the jamma loom component side connector must of been plugged upside down where the +5v killed the chip.
Thats far i can go with this one and to repair this fully i just need that chip so if anyone got a scrap taito pcb with that chip
then please drop me a pm.
.Checked the z80a on pins 15 and 16 but now they are high only,decided that the z80a must be bad so i removed it and put in a socket and a good working z80a.
Fired it up but still no sound
,scoped pin 15 and 16 on the z80a and it was now active which was a good sign.Next i scoped the 64k sram (ic30) which is located above the sound rom,scoped all outputs and i found that outputs at pin 15 and 16 showed up bad signals.Removed the ram and put in a new socket and ram. Fired it up and................😭 still no sound,scoped the sram and all outputs looked ok,next i scoped the yamaha sound generators analogue outputs pins 18,19 and 20 above the sram and showed no signal (dead outputs).
Luckily this was already socketed,put in a new one and fired it up.........................................🤞
ohhh yes music to my ears
,finally got the sound working.heres a pic of the parts i have removed. Now that the game has its graphics back and sound the last fault to tackle is where when you credit and start the gamethe plane goes up on its own and keeps bombing.
Ok while the game was running i checked all the player 1 and player 2 inputs at the jamma edge connector.
Normally they should be pulled up to +5v and they were except pin 18(player 1 up) and pin 23(player1 bomb),
my meter checked out as +2.4v which is low?followed all these inputs and they got to 4 resistor arrays,inputs for up and bomb goes to rc1 and rc2.Measured the internal resistors which are 100 ohms and checked out ok so this got me thinking
that the custom chip (TC0220IOC) might be bad.What i did was to remove these two resistor arrays from the pcb and powered on and the inputs to the resistor array went to +5v which is good but output from the array was +2.4v so unfortunately the custom chip is bad.
ahhhhhhhhhhhhhhhhhh i hate custom chips 🤬,heres a picture of the chip.
Its possible that the jamma loom component side connector must of been plugged upside down where the +5v killed the chip.Thats far i can go with this one and to repair this fully i just need that chip so if anyone got a scrap taito pcb with that chip
then please drop me a pm.
