Gyruss - just a black screen

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So I've had issues with my Gyruss board since I got it. The primary concern was a burnt up pin on the edge connector which I repaired using copper tape. At some point I had to do it again which turned out better than the first time since I knew a little better about what I was doing.

Unfortunately, now the game doesn't boot at all. Voltages check out fine and I've verified that it's not the monitor (meaning it doesn't play blind). I tried shoestring's test rom tonight and that didn't come up either. If I understand correctly, that should be the first code to run at start up if the chip is present so if that doesn't work then that should help narrow things down, yeah?

Anyone have any ideas to get me pointed in the right direction? Hoping it's just something stupid I'm overlooking or simply not thinking to check.

Just once I'd like it to be that easy :D
 
So I've had issues with my Gyruss board since I got it. The primary concern was a burnt up pin on the edge connector which I repaired using copper tape. At some point I had to do it again which turned out better than the first time since I knew a little better about what I was doing.

Unfortunately, now the game doesn't boot at all. Voltages check out fine and I've verified that it's not the monitor (meaning it doesn't play blind). I tried shoestring's test rom tonight and that didn't come up either. If I understand correctly, that should be the first code to run at start up if the chip is present so if that doesn't work then that should help narrow things down, yeah?

Anyone have any ideas to get me pointed in the right direction? Hoping it's just something stupid I'm overlooking or simply not thinking to check.

Just once I'd like it to be that easy :D

CPU running? (Clock, Address, Data)?

Does it have any audio?

If CPU is running, would start by checking RAM.
 
Are you getting a black screen or a blank screen ?

Yes there's a difference :)
That's fair :) It's a solid black when connected to the PCB but has some wavy lines when not connected to the board, if that helps distinguish the two.
 
There's sync and some signals then. It's hard to say without seeing this in person.

Do you hear any kind of popping or ticking sound from the speakers with the board connected ? .This would indicate the watchdog barking to get the CPU to restart, this is usually caused by a bad EPROM or work RAM, sometimes a bad TTL ( highly likely in a Gyruss because they use a high number of these troublesome Fujitsu TTL logic chips ).

The sockets in these things are quite bad. After so many years the sockets lose their springiness and contact with the IC and make the board unstable. So carefully re-seat them especially the ones on the bottom board and see if that will kick things off. Eventually these boards will need new sockets so re-seating will only get you so far.
 
on these and T&F boards I add additional 18 gauge wires from the power supply to the plugs that bounce power from the main board to the other board. (literally solder +5 to the red wire pins, ground to the black wire pins) consider this the equivalent to a test point mod on Pole Position. this will net you 2 additional +5 and ground feeds each, and direct shots to each board so you're not piggybacking exclusively anymore. if you desire even more grounds, you can always tap into the logic grounds for the controls and coin door and beam those back to the power supply ground.

the Konami wiring harness has a single ground wire to the power supply. why they felt that was a good idea, powering one board with another no less, is beyond me. that's vastly inefficient and insufficient for the game's power needs, and is exactly why the edge connector burns up -- just like a Pole Position would, except there's no Sense, it's just poor grounding that generates the heat.
 
There's sync and some signals then. It's hard to say without seeing this in person.

Do you hear any kind of popping or ticking sound from the speakers with the board connected ?
There is a pop when it starts up - I'll pay more attention to it tonight and also try reseating the sockets and such.

the Konami wiring harness has a single ground wire to the power supply. why they felt that was a good idea, powering one board with another no less, is beyond me. that's vastly inefficient and insufficient for the game's power needs, and is exactly why the edge connector burns up
That's interesting and makes a lot of sense. Sounds like a worthwhile mod to me.
 
on these and T&F boards I add additional 18 gauge wires from the power supply to the plugs that bounce power from the main board to the other board. (literally solder +5 to the red wire pins, ground to the black wire pins) consider this the equivalent to a test point mod on Pole Position. this will net you 2 additional +5 and ground feeds each, and direct shots to each board so you're not piggybacking exclusively anymore. if you desire even more grounds, you can always tap into the logic grounds for the controls and coin door and beam those back to the power supply ground.

the Konami wiring harness has a single ground wire to the power supply. why they felt that was a good idea, powering one board with another no less, is beyond me. that's vastly inefficient and insufficient for the game's power needs, and is exactly why the edge connector burns up -- just like a Pole Position would, except there's no Sense, it's just poor grounding that generates the heat.

I have huge voltage drop on my Circus Charlie and Scramble. CC has that red/black connector but Scramble doesn't. I'll try that on CC and see if I get rid of that last random red dot in the screen, lol. I had made a thread about it but got no interest, it seemed.

http://forums.arcade-museum.com/showthread.php?t=388682
 
I do have a version of my Gyruss test rom which is used in place of one of the existing game EPROMs. It cannot be used in that socket permanently though like in my previous version.

It's only a used as a means for providing power up tests and does not include any diagnostic mode. This is essentially for people who suspect having screwed up game EPROMs and want to test the rest of their hardware.

I haven't released it yet, I need to test this on my PCB before I do that.
 
I have huge voltage drop on my Circus Charlie and Scramble. CC has that red/black connector but Scramble doesn't. I'll try that on CC and see if I get rid of that last random red dot in the screen, lol. I had made a thread about it but got no interest, it seemed.

http://forums.arcade-museum.com/showthread.php?t=388682

yeah, if you have nowhere to tap into you can always use the corners of an IC to feed voltage in. there's the famous picture in my PSU guide of where to measure voltage on an IC, solder wires to those points accordingly.
 
Well I think I fixed it for now. I was looking the board over after troubleshooting some of the suggestions above to no avail, and in the right lighting I noticed what looked like a small spot on one of the GND pins that was shinier than elsewhere - the pin next to the one I repaired. Figured I knew exactly what it was as soon as I saw it...checked continuity to be sure and there were a few spots on that pin that were basically covered in a very very thin layer of the epoxy I used in my last repair. Sigh.

Cleaned up that pin, fired it up, and the diagnostic menu came up. Going to run it like this for a while to make sure that was indeed all it was before I reinstall my save kit.

Unbelievable...

Thanks everyone for the suggestions. I probably wouldn't have found it right away if I hadn't been reseating socketed roms and such.
 
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