Sync problem on zn-2 - solved!

[wasspat]

hi guys,

I’ve got trouble with a motherboard Zn-2. It’s for sure from the motherboard because I tested with two daughter boards (rival school and sfex2) and the game works on my other motherboard.
With this one, you can see the game with a very dark image and the sync is definitively not good. Without game, I’ve blue screen with the same sync problem.
On the motherboard I can see a repair on one chip : IC603 74LS374.
Do you have an idea where I must focus my attention? Crystal? Sony chips? The 74LS374?

Thanks a lot for your advices .

 

[wasspat]

after a good sleep and a MP from A-P, I was reminded than Zn and G-net system are about the same main hardware so with a search with sync + g-net I found this great topic : https://www.arcade-projects.com/forums/index.php?threads/taito-g-net-wont-sync.5955/

During my previous analysis I’ve tracked the signal from sync on jamma and I’ve ended to the IC 74F244 on pin 4 on the lower part. On the topic of twisted symphony, he said his problem sync was done by changing this IC. Hmmm, I thought it was worth to try .

So, I removed a F244 from a dead tekken board and I replace it on my zn-2 .... and now all is good .I’m very glad having this particular IC in spare thanks to the dead tekken .