Bootleg PCB King of dragons GAL20V8

PCB problems and fixes
Post Reply
Kernel32
Please Continue...
Posts: 25
Joined: February 23rd, 2014, 12:16 am
Location:

Bootleg PCB King of dragons GAL20V8

Post by Kernel32 »

Hello
I have a bootleg PCB with the game King of Dragons (from CAPCOM)
Image
The board is considered dead, blue screen with waves.
I did some tests and i found continuity between ground and VCC, I found the faulty chip, it's a GAL20V8 shorted between ROMs 3 and 4 (on this board I have 1 GAL20V8 near the CPU, and 2 GAL16V8 near maskroms)
So my question, where can I find the program to load inside the GAL20V8 ?
My board seems to be the same like "Cadillacs and Dinosaurs" = http://www.jammarcade.net/pal-dumps/Do you think is it a good idea to load this .JED : http://www.jammarcade.net/files/pals/Ca ... 0v8a-1.jed" to test if I have a boot ?

I tried to read and backup the 2 GAL16V8 but I can't read with my EPROM programmer Minipro 866, I think they are locked ...

Have a nice day and Thank you.

PS : I found the short with a multimeter / continuity test, the first test to do before power on, and to find the faulty chip I power on and put fingers on the board, I detected 2 very hot chip, and one of those was Dead.
Last edited by Kernel32 on March 22nd, 2014, 4:03 pm, edited 3 times in total.
porchio
Please Continue...
Posts: 60
Joined: November 14th, 2010, 8:37 am
Location: Cumbria

Re: Bootled PCB King of dragons GAL20V8

Post by porchio »

Generally PLDs run quite hot.
Where was the short on the chip?
Something else to keep in mind, just because the continuity tester beeps doesn't necessarily mean there is a short. What was the resistance?

I recall on my Silent Scope boards the resistance between VCC and GND was about 16ohms so the continuity tester did beep even though the circuit was fine.
User avatar
caius
Posts: 112
Joined: May 24th, 2013, 11:55 am
Location: Italy
eBay: private
Initials: FAB

Re: Bootled PCB King of dragons GAL20V8

Post by caius »

I have this board but sadly I can't dump the locked GAL20V8A since it's 24 PIN PLD.I think you can't use the PLD from Cadillacs & Dinosaurs even if PCB layout is the same but memory map is different.
Kernel32
Please Continue...
Posts: 25
Joined: February 23rd, 2014, 12:16 am
Location:

Re: Bootled PCB King of dragons GAL20V8

Post by Kernel32 »

Hi,
@ porchy : the short is between the ground and the VCC pin, I have continuity, I will check this evening the resistance ... (but i also checked on my programmer and I can't do the test due to the short)

@ caius : Ok thank you, I will try to find a way to repair this board ...

Have a nice day
Kernel32
Please Continue...
Posts: 25
Joined: February 23rd, 2014, 12:16 am
Location:

Re: Bootled PCB King of dragons GAL20V8

Post by Kernel32 »

porchio wrote:Generally PLDs run quite hot.
Where was the short on the chip?
Something else to keep in mind, just because the continuity tester beeps doesn't necessarily mean there is a short. What was the resistance?

I recall on my Silent Scope boards the resistance between VCC and GND was about 16ohms so the continuity tester did beep even though the circuit was fine.
I checked the resistance it's 15,6ohms.
User avatar
caius
Posts: 112
Joined: May 24th, 2013, 11:55 am
Location: Italy
eBay: private
Initials: FAB

Re: Bootled PCB King of dragons GAL20V8

Post by caius »

Did you test the resistance betwenn GND and VCC of the GAL desoldered from PCB or still soldered?
Kernel32
Please Continue...
Posts: 25
Joined: February 23rd, 2014, 12:16 am
Location:

Re: Bootled PCB King of dragons GAL20V8

Post by Kernel32 »

No I tried desoldered because the board is shorted.
Without the GAL I don't have continuity between GND and VCC on JAMMA connector.
If you want I can solder the PAL on the board to test the resistance if it's necessary.
Kernel32
Please Continue...
Posts: 25
Joined: February 23rd, 2014, 12:16 am
Location:

Re: Bootled PCB King of dragons GAL20V8

Post by Kernel32 »

Hello
I programed a new GAL20V8 with the first set of "Cadillac and Dinosaurs" and now I have always a blue screen (but without waves) and I have sound, so It's a good begining :D
I checked the 68000 CPU I have pulse and reset pin HIGH but no activity on adress data pins.
I verified every ROM and MASKROMS they are OK.

Sometimes when I boot the game I have a strange screen with some 00 and & etc ...

I tried to program other GAL20V8 from the game "Cadillac and Dinosaurs" but only the first set give me something = the sound

I received the logic comparator I will check logic TTL ..
Kernel32
Please Continue...
Posts: 25
Joined: February 23rd, 2014, 12:16 am
Location:

Re: Bootleg PCB King of dragons GAL20V8

Post by Kernel32 »

Hello
the board is in watchdog mode, I'm looking for the bad TTL ... ;)
Post Reply