Centipede problems with pics and voltages

[pipcade]

My Centipede worked 100% 2 years ago. I pulled the working PCB to use to test another cab and then put the PCB in a box that was fairly well protected. I ended up pulling the monitor too for another project. I go to put it back together recently and she doesn't work now.

I had the PCB set to free play. When I powered it up with no monitor now I see the start buttons are staying on and not blinking like they used to. I check some voltages and turn the voltages down a bit and now the buttons do blink. I can hit one of the start buttons and it stays lit and the other goes off. I get NO sound at all. Nada. I hook it up to a monitor (then another then another) and I get the pics you see here:
http://thebrokenjoystick.com/misc/centipede/

Basically, it's a green line through the middle that moves a bit randomly and then a thicker red line that sometimes stays at the top or bottom and sometimes scrolls through. No sign of any Centipede graphics at all. I can take a video of it if it's important.

If I press a start button it stays lit and eventually goes back to both blinking which makes me think the game is actually playing and eventually all lives are lost and it goes back to blinking.

I tested the voltages on the PCB next to the connectors and got this:
+5 = +4.85
+12 = +11.53
-5 = -5.36
+22 = +24.1
-22 = -24.5

That's pretty much all I know to do now. I searched these forums and google and realize there is a lot that can go wrong but I'm not sure where to go next. Can anyone point me in the right direction as to what to do now? I don't know if it's my cabinet/voltages or the PCB that has the problem. Any help would be appreciated.

Thanks,
Brian

 

[kstillin]

Hey brother!

That doesn't look too good at all. It looks like you have a video raster, but the game board isn't putting out a decent picture.

I would bump the +5V line up to 5 or slightly over (5.1 max).
There should be a test switch on the coin door near the hinge. You may be able to get some beep codes out of it for RAM/ROM problems. If you're getting no sound at all, the audio section on the AR board may not help with the beeps.

In test mode, every button press should trigger another tone.

The good news is that Centipede boards are usually cheap. Maybe $75 or so. I have had a few flaky ones that I gave up on. I did have success fixing a trak-ball problem once.

Good luck-
Kerry

 

[bit_slicer]

Try test mode. Also double-check and make sure you have the monitor hooked up correctly. Make sure you have horiz and vert syncs hooked to the positive inputs at the monitor and not the negative. If the video hookup is correct, then you likely have a problem on the board at the video summing circuit and/or H/V sync outputs.

 

[pipcade]

Update... a buddy took the PCB home and got some Centipede graphics from it on his test bench. I hook it up in my cab and don't. Difference is - he used the test pins on the PCB whereas I used the Centipede connector/harness. So... We suspect my harness/connector isn't behaving. I'm going to to test it in my Centipede cabinet but pull the video from the test spots on the PCB too (and check continuity from the test pins to the harness/video connector).

Will let you know what I find.

 

[pipcade]

Ok, big update. Turns out I'm an idiot. My test rig was using the video outputs wrong. I had RGB, gnd sync going into sync gnd BGR (backwards). DUH! Did it correctly and I got a picture. No mushrooms though and still no sounds. Similar to another thread here.

I went to bed and turned it on the next day and it all worked again - sounds and mushrooms, everything. No idea why. I didn't change anything. Anyone know what could cause that? I'm glad it's working again but worried it might stop working again at any time.

 

[kstillin]

I went to bed and turned it on the next day and it all worked again - sounds and mushrooms, everything. No idea why.
...
I'm glad it's working again but worried it might stop working again at any time.

Don't worry- just be happy