Help with GameKing bootup

[Blueridgeslots]

I think I would try the old chips and simm in the new cpu first (don't even clear it) and see what happens then.

My guess is that copied set has a bad chip or a label is mixed up, since they are copies and you have a burner, get the seller to see if he was one who did them and have him send you the files to compare chips

[jimhowardjr]

Hi -
I tried my old chips in the new board and now the screen is still color pixelated but flashes and the colors change a little. 

I also tried the new chips in the old board and just get the color pixelated screen again.   I doubled checked that all of the chips were in the correct position and seated properly - all chips legs in place.

As I mentioned before the key 40 chip worked in both boards and I was able to reset all three and reboot fine.  Still can't get the machine working though    

I've also contacted the seller of my new board/chips to see if he has the files for the chips so that I can compare.

Any other suggestions that I can try? 

I also have a chip burner so if anyone has the checksums on these chips so that I can check them to make sure they're at least the same, that would be great.

I attached a photo of the old chips in the new board.

Thanks!

Jim

[Tilt]

Check your +13 and +25VDC power supply output voltages and see what they are.  You can measure them at J13 where the power connects to the motherboard.

[jimhowardjr]

Hi Tilt,

Thanks for the page - that made it easy to test.   The voltages on my machine are 12V and 23.1V

Jim

[Tilt]

Those are both pretty low.  Do you have another power supply that you can swap it out with?  It's the same as in a S2000 if you have one.  Low DC voltages can cause the grey pixelated screen too.  Since you have essentially the same issue with second MPU I would replace the power supply before going too much further into them. 

[jimhowardjr]

Tilt,

Unfortunately this is the only IGT machine I have.  The only other machine I have is a Bally 6000.

I guess I'll have to see if I can find one on nlg

Thanks,
Jim

[jimhowardjr]

Thanks for the power supply suggestions.  I opened the power supply and found a blown cap.

Hopefully, that's all it is

Jim

[Tilt]

Yep, that cap has definitely seen better days!

[DanTheMan]

I have seen this pixelated screen caused by a damaged PCB trace on the 039 board. There is some read/write decode logic just to the right (notch) side of the BASE chip and there is a tiny trace that passes right below the BASE socket that can be damaged by using a screwdriver to pry the chip out of the socket. This signal (SRAM OE/) travels from U25 pin 8 to the SIMM sockets, the SRAM sockets (pin 24) and the EPROM sockets. If I remember correctly, if you pull the RAM chips out and you start it up, the pattern will go away. Use an ohm meter or continuity tester to follow the signal and see if it is missing. Then you just have to solder a replacement wire in its place.


I highly recommend this tool for extraction of the EPROMs. http://www.amazon.com/Jonard-EX-2-Extraction-Tool-24-40/dp/B006C3Y8IY

[jimhowardjr]

Hi all - UPDATE


thank you all for your help.  I replaced the bad cap on the board (now the voltages are correct), key chipped, and it booted up...it's alive!!


I'm using the new MPU and chip that i bought and the old chips are still producing pixelated screen.  I think one of my chips is bad.  I'll have to buy another set of 792's...or I have a chip burner if someone could help.


Nice!


Jim

[Amechanic]

Great to see its back up and running. I still have that set of 792 GK software if your interested. Let me know if your interested. I'll make you a great deal on the set.

[jimhowardjr]

Amechanic,

Thanks for the offer.  Some already hooked me up and now it's working!

Jim

[Amechanic]

Not a problem. Just saw your post still looking for a set of 792 GK software. Maybe I'll post it here for sale then. I have a couple complete factory sets.


Gary