Motherboard sega system 18 with Sega blast city

[SlipDerMan]

Hi my friends,

I'm having a little trouble getting Shadow Dancer to work on System 18.

I have two types of motherboards:
* one with 2 oscillators
* the other with 3 oscillators.

I'm testing all of this on different Blast City arcade cabinets (one with an MS2933 board, one with an MS2931 board, and one with an MS2930 board)... when I use Shadow Dancer with the 2-oscillator motherboard, I get a synchronization problem and a blurry image on the screen. However, regardless of the Blast City cabinet used, when I try Shadow Dancer with the 3-oscillator motherboard, the game works perfectly on all three cabinets.

A friend gave me some invaluable advice (Dom, you're the best!), which was to connect pin 14 of the JAMMA connector to the 4 GND pins (1/2/27/2. That's what I did, but I'm still having the same image synchronization problem with the dual-oscillator motherboard.

Do I need to change the GALs? Is there something I need to do on the boards?

Do you have any suggestions?

However, I tested the Shadow Dancer + dual-oscillator motherboard on a Euro arcade cabinet and via a Supergun, and it works perfectly... it's only on Blast City machines that I have image problems.

Thank you for your help.

This message will self-destruct.

Best regards.

 

[Ape Cosplay]

Hi,

It is a well known issue of 2 oscillator motherboards hence the 3 oscillator update.
A bit ironic it impacts Sega cabinets...
The problem isn't the floating pin 14 like you can have on bootlegs or GAL related but rather an incompatible sync signal.
I guess if you studied the differences between the two motherboard revisions you could design a fix (probably not very nice, with bodge wires, etc.).

 

[SlipDerMan]

Hi,

It is a well known issue of 2 oscillator motherboards hence the 3 oscillator update.
A bit ironic it impacts Sega cabinets...
The problem isn't the floating pin 14 like you can have on bootlegs or GAL related but rather an incompatible sync signal.
I guess if you studied the differences between the two motherboard revisions you could design a fix (probably not very nice, with bodge wires, etc.).

Wow!

Thank you for your very quick reply.

Could you provide a tutorial for this repair?

Thank you.

 

[Ape Cosplay]

I don't have an out of the box solution, just giving some ideas. I don't think I even have both types of motherboards to compare myself.

 

[andydex]

I have a system 18 dual oscillator that doesn't sync properly on my SD capable 14" PVM but syncs no problem on my HD capable 14" PVM. I can't figure it out either.