Super Cobra PCB problem

sundodger

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Recently aquired a Super Cobra to go in my scramble cab.
One of the wires on the ribbon cable was burnt so replaced that and now it starts up to show the attached screen.
also a humming from the speaker.
My scramble board plays fine in this cab.
Where to start guys..
Thanks
 

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It's bad English, but... Wires don't burn for no reason!

Look on the board that's at the other end of the ribbon cable for burnt traces, hot chips, or any kind of heat looking damage. This would include writing on chips that have turned darker color over the center of the chip.

Also, look to see that you have all the proper voltage levels on the different boards.

RJ
 
Good point, it was pin 28 or 29. Looks like the board has had work before see new picture
 

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I had a very similar screen on one of my Anteater pcb's (which runs on a hacked Super Cobra board ) and it turned out to be a bad Z80, so you might want to try swapping yours out before you dig any deeper...
 
Have never had to test a board before, have had a look and see nothing burnt.
How would i go about checking the voltages, i assume going in is good as scramble plays.
So it must be check at certain points on the board right?
Thanks
 
Looks like the game is not running code. So start by looking at the ROMs (those boards are notorious for bad sockets) and the processor.
 
ok pulled anything with a socket cleaned and reseated. no change.
swapped the Z80's one at a time and put them into the soundboard on my scramble pcb. One produced no sound the other did, so one bad Z80. however on putting other Z80 from scramble onto the board so i have 2 known good Z80's on the super cobra no change.
What would you check next guys?
 
Read the ROMs and compare checksums to known good dumps...
 
Recently aquired a Super Cobra to go in my scramble cab.
One of the wires on the ribbon cable was burnt so replaced that and now it starts up to show the attached screen.
also a humming from the speaker.
My scramble board plays fine in this cab.
Where to start guys..
Thanks

I'm curious to read your findings on the audio hum... I have a Moon War, which I think is the same hardware as Super Cobra. I bought it with a ROM error and got it working again by getting a new ROM set from Steph at hobbyroms.

It has a loud audio hum, but I'm not sure if its a board problem or something else. I did notice it has the wrong value volume pot and a car speaker. I've been backlogged with projects so I haven't really done anything with it in a couple months.
 
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