Space Firebird - player 2 problem.

[Macro]

I have a space firebird PCB that for player one (or in an upright!) works fine.



However as soon as it rotates the screen for player 2, it has corrupt graphics.



I've replaced all of the LS86's that invert the signals when RV is active, along with the LS283 adders that also have not RV signal as the input carry. No difference.

Everything else seems to be common to whatever way it draws the screen (ram / rom etc.)


Anyone fix these ??

 

[TheDaddy]

Not done one but are you sure its set to 'Cocktail' ? Just a thought.



Dave.

 

[jbtech]

Hi, it seems to be reversing the background and text correctly but the sprites appear to be scattered in the vertical axis.
I have worked on Space Firebird but not with this type of issue, did you spot this LS 86 on the video PCB?



Good luck with it, regards John

 

[Macro]

Yes, replaced that one. It's such a weird piece of hardware, uses 74LS86 XOR gates with one of the inputs wired to 5v to invert signals (instead of a 7404 like most other things), uses fast adders to offset addresses and BCD counters for the stars.

Basically it uses lots of TTL and ram chips that most other arcade boards don't - I keep having to order them in (and some are quite pricey!) - fortunately the 64 x 9 static rams all test OK.

 

[Ronnie Dent]

I can't help with the fault but having owned a table for many years I have built up a fair stock of boards most being faulty! I think I have around 12 sets, Might not help but the sockets can be poor on these boards

 

[philmurr]

Yes, replaced that one. It's such a weird piece of hardware, uses 74LS86 XOR gates with one of the inputs wired to 5v to invert signals (instead of a 7404 like most other things), uses fast adders to offset addresses and BCD counters for the stars.

For completeness do you have a list of all the parts you've already replaced?

Agree it's very strange hardware (not to mention how odd the software is too, I gave up on modding it...)