Jailbreak missing FX

[Lurch666]

An original Konami PCB was producing speech but no sound FX.
No schematics and not much I could find online but fortunately I have a fully working boardset and an audio probe to help.

Using the probe I found the FX comes from pin 7 of a 76489 at D6. There was data going to it but the ready pin 4 was stuck high. On my working board it went low every time FX was produced.
Then I checked pin 6 which was the OE and it was floating. This led to the output of a fujitsu LS08 at C6 and of course it was faulty.
A quick piggyback and FX are back.
Now to replace it to get this PCB is fully working.

 

[Retroman839]

Nice 👍😎
How does your probe show floating ?

 

[sukhbir]

An original Konami PCB was producing speech but no sound FX.
No schematics and not much I could find online but fortunately I have a fully working boardset and an audio probe to help.

Using the probe I found the FX comes from pin 7 of a 76489 at D6. There was data going to it but the ready pin 4 was stuck high. On my working board it went low every time FX was produced.
Then I checked pin 6 which was the OE and it was floating. This led to the output of a fujitsu LS08 at C6 and of course it was faulty.
A quick piggyback and FX are back.
Now to replace it to get this PCB is fully working.

As always another nasty fujitsu logic chip.

 

[Lurch666]

Nice 👍😎
How does your probe show floating ?

I used an oscilloscope probe to check the state of the pins. It showed it floating as it was stuck at about 1V.
Sorry I should have clarified.

 

[Retroman839]

I used an oscilloscope probe to check the state of the pins. It showed it floating as it was stuck at about 1V.
Sorry I should have clarified.

That’s cool !
And good would be around 3v?

I got a blood brother I’m about to start probing for life on the cpu/bffers for the rams

 

[Lurch666]

TTL logic should be either 5V or 0V (actually just above 0V) or toggling in between.
If an output of a chip is sitting at 2-3V when the inputs are active then it's probably a fujitu that's failed.

 

[Retroman839]

That’s cool !
And good would be around 3v?

I got a blood brother I’m about to start probing for life on the cpu/bffers

TTL logic should be either 5V or 0V (actually just above 0V) or toggling in between.
If an output of a chip is sitting at 2-3V when the inputs are active then it's probably a fujitu that's failed.

Cool ..,
If I do have life on the cpu I will start a new thread

 

[Retroman839]

Vídeo custom missing 🤣
O well thet explains it ..
Cauis has repro..

It most likely went on a Raiden