Solved The New Zealand Story - random errors + watchdog

[Georgian2]

Hello,
I'm stuck here with this double tnzs board. I got it from ebay. it loogs like it has been washed. All the rams are tested and ok, eproms too. Still it gives this erros on every boot. Anybody got any ideea?

Thanks a lot.

 

[Jacmar]

connection issues between boards?

 

[Georgian2]

I don't know. It could be anything. It would be great to know the order of checks so I know what eeror comes first.

 

[Ace`]

Something in the video ram circuit judging by the errors.

 

[Georgian2]

Something in the video ram circuit judging by the errors.

Which one is the video ram?
https://github.com/jotego/jtbin/blob/master/sch/tnzs.pdf Schematics of this board.

 

[Ace`]

The 6264 (A5) on page 4 according to those schematics is object ram.

 

[Georgian2]

The 6264 (A5) on page 4 according to those schematics is object ram.

Already changed that.

I noticed that the pin 1 of the 62256 ram on top board is not connected like it is in the schematics.
Dose anybody have this boardset and can make some measurements?

 

[Ace`]

Pin 1 on a 6264 is a no connect, and if the ram is okay then it's something else in the circuit that's bad.

 

[Georgian2]

Pin 1 on a 6264 is a no connect, and if the ram is okay then it's something else in the circuit that's bad.

On the top board the ram is 62256.

I put new roms and gal for testing purpose.

 

[Georgian2]

it is connected like this. Also the MDC0 is not used in any equations on that PAL???

 

[Georgian2]

I've been looking at the wrong schematics from the PLD archive because I have them printed out. On github they are a bit different... 🥵

 

[Georgian2]

I still have an hard time finding what is wrong with this board....
sub and audio CPUs are not running because the SRST is always low, because the BNKSW dosen't do anything either....


Also there is no actvity on the LS174 because the pin 9 dosen't change at all.... I did replace the PAL with no change at all.

 

[Georgian2]

Changing the HC245 at A2 gave an solid SUB CPU ERROR. Great progress! Pigybacking all other Fuitsu 245 brought the game back to life. 🥳
🥳 🥳 🥳 🥳 🥳
Gues I'll just swap all the fujitsu chips...
Problem solved.