Ghosts n Goblins with 4 faults

Fixed a PCB? Tell us how!
Forum rules
You can add Repair Logs to the Wiki here.
User avatar
system11
Posts: 344
Joined: September 21st, 2008, 1:14 pm
Location: Cambridge, UK

Ghosts n Goblins with 4 faults

Postby system11 » October 15th, 2011, 10:43 am

I bought an untested Ghosts n Goblins board this week, knowing it would almost certainly be broken.

When it arrived, the game was running but the background graphics were a mess of repeated tiles and the sprites had horizontal jailbars. I took it upstairs to the test bench, left it running for a moment or two and then everything went black.

Checking the code ROMs there was no activity at all, in fact nothing on the board was pulsing. First thought was that this would probably be the crystal, so I replaced it with a known working one and the fault remained. The timing circuit on Ghosts n Goblins is on page A-2 5/8 of the schematics here on the left hand side:

http://arcarc.xmission.com/PDF_Arcade_Manuals_and_Schematics/Ghosts%20and%20Goblins%20Schematics.pdf

As you can see it gets voltage from the chip in 3N which is a 74LS04 flip-flip. Replacing this chip fixed the clock signal. Important note here, this one actually kept me going for a while because initially the new chip didn't work. I tried a 7404 next and it was fine, with more testing it turns out that the circuit is quite fussy about which LS04 you have in there, changing resistor R44 for a slightly different value might sort that out. A brand new Fujitsu didn't work at all, but an old Motorola I pulled from a parts board worked just fine, as did a brand new Fujitsu 7404.

So I had the game running again, but the sprites had now vanished completely... I decided to sort out the backgrounds first, the second board in a GnG set is the video board, looking at it with the ribbon connectors at the top, the set of ROMs on the right are background tiles. Checking the address lines on these showed that address lines on pins 2-5 were stuck except for one with a signal so weak that the logic probe would just flicker for half a second and die. The ROMs are on B-2 9/9 on the schematics, showing that these address lines go back to a 74LS273 on page B-2 8/9, location 5A on the PCB. 273s are a larger flip-flop, and if you can see activity on the inputs and patchy or floating outputs, it's usually a safe bet that the chip has failed. Sure enough this looked dead, replacing it fixed the backgrounds.

Next I had to get the sprites back, so I started at the ROMs looking for activity, which are on page B-2 4/9 on the schematics, and bottom left of the board with ribbons at the top. The address lines were showing activity on them, but the CE (chip enable / select) lines which you would expect to see pulsing as various ROMs are accessed, were stuck high on two pairs and stuck low on the third pair. These are connected to a 74LS139 decoder near the ROM layout jumpers at the bottom of the board, but the inputs to that were also stalled. Going back to the schematic, the lines coming to the jumpers are AD8 (label missing) and AD9, so going to page B-2 3/9 we can see that these should come from a 74LS273 at position 8J. While the lines were stuck, they all looked solid. 273s take a clock signal, and checking pin 11 showed that the clock was dead, no signal at all. Following the schematics we can see that the clock line goes back to a 74LS139 at position 9K. This had healthy inputs, but one of the four outputs was dead - replaced and the sprites came back to life.

Finally there were just the jailbars to deal with. The jailbars were horizontal, and not changing position with the sprites which usually suggests a RAM issue rather than ROM access. The sprite RAM is at 12N and 7N on the PCB, pages B-2 5/9 and 6/9 on the schematics. While both showed activity on address and data lines, the data lines on 7N seemed a little quieter. I started checking the 74LS257 and 74LS273 chips attached to the data lines, and sure enough - the 273 was looking sick. Replaced and the game was finally fixed.

We can learn several things from this. One - the release of the schematics (quite recently) was an absolute god send. These boards have a mask that covers all the tracks, making diagnosis without them a very long and miserable process trying to work out which chips connect to which others. By now many with simple faults will have been binned because diagnosis was simply too time consuming. Secondly, always suspect the flip-flops. My first ever PCB fix was a broken flip-flop, and I've replaced many over the years. Multiplex/demultiplex seem to be the next most common TTL failure, maybe it's just luck.
Random blog of stuff:
http://blog.system11.org
User avatar
davewellington
The Librarian
Posts: 1586
Joined: July 7th, 2010, 1:42 am
Location: Wellington, New Zealand
Initials: DAV

Re: Ghosts n Goblins with 4 faults

Postby davewellington » October 16th, 2011, 4:40 am

Thanks for posting, and thanks for the schematics link, very useful :)
all your wiki pages belong to me
User avatar
thomj
Just a few screws loose
Posts: 1949
Joined: June 13th, 2010, 12:05 am
Location: East Yorkshire
Initials: TWJ

Re: Ghosts n Goblins with 4 faults

Postby thomj » October 16th, 2011, 12:43 pm

I enjoy reading these although I have no ability to do any of this :awe:

It's a great thing to record the knolwedge people game when they mess about with this stuff.

I have a GnG to send off for repair soon. Doesn't seem as far gone as yours was though.
User avatar
Runik
Posts: 15
Joined: August 19th, 2011, 11:54 am
Location: France
eBay: runik_fr
Initials: RNK

Re: Ghosts n Goblins with 4 faults

Postby Runik » October 18th, 2011, 12:24 pm

Really interesting, thanks for sharing :thumbup:
RallyArmor
Posts: 16
Joined: November 7th, 2014, 6:52 pm
Location: USA

Re: Ghosts n Goblins with 4 faults

Postby RallyArmor » December 23rd, 2014, 4:26 pm

Finally there were just the jailbars to deal with. The jailbars were horizontal, and not changing position with the sprites which usually suggests a RAM issue rather than ROM access. The sprite RAM is at 12N and 7N on the PCB, pages B-2 5/9 and 6/9 on the schematics. While both showed activity on address and data lines, the data lines on 7N seemed a little quieter. I started checking the 74LS257 and 74LS273 chips attached to the data lines, and sure enough - the 273 was looking sick. Replaced and the game was finally fixed.

We can learn several things from this. One - the release of the schematics (quite recently) was an absolute god send. These boards have a mask that covers all the tracks, making diagnosis without them a very long and miserable process trying to work out which chips connect to which others. By now many with simple faults will have been binned because diagnosis was simply too time consuming. Secondly, always suspect the flip-flops. My first ever PCB fix was a broken flip-flop, and I've replaced many over the years. Multiplex/demultiplex seem to be the next most common TTL failure, maybe it's just luck.


I have a similar issue, except that the jailbars on my system are vertical. In your opinion, would this be a RAM issue or should I start probing other chips on my board? I have a CPS1 A board that is showing vertical jail bars when connecting ANY CPS B board to it.
User avatar
system11
Posts: 344
Joined: September 21st, 2008, 1:14 pm
Location: Cambridge, UK

Re: Ghosts n Goblins with 4 faults

Postby system11 » December 23rd, 2014, 5:44 pm

Are they static overlaying the image or do they seem anchored to sprite position?
Random blog of stuff:
http://blog.system11.org
RallyArmor
Posts: 16
Joined: November 7th, 2014, 6:52 pm
Location: USA

Re: Ghosts n Goblins with 4 faults

Postby RallyArmor » December 23rd, 2014, 5:52 pm

system11 wrote:Are they static overlaying the image or do they seem anchored to sprite position?


They seem to be static.
Attachments
$_57 (2).jpg
User avatar
system11
Posts: 344
Joined: September 21st, 2008, 1:14 pm
Location: Cambridge, UK

Re: Ghosts n Goblins with 4 faults

Postby system11 » December 23rd, 2014, 6:00 pm

Probably a stuck address line somewhere, I'd try a new A board just to verify that's where the fault is (which it probably is).

Honestly I just replace CPS boards, they're complex and common.
Random blog of stuff:
http://blog.system11.org
RallyArmor
Posts: 16
Joined: November 7th, 2014, 6:52 pm
Location: USA

Re: Ghosts n Goblins with 4 faults

Postby RallyArmor » December 23rd, 2014, 9:56 pm

system11 wrote:Probably a stuck address line somewhere, I'd try a new A board just to verify that's where the fault is (which it probably is).

Honestly I just replace CPS boards, they're complex and common.


Yes, I tried with a new A board and the graphics are fine. So I've isolated the problem to being a faulty A board. Just wondering if an A board can be repaired. They're hard to fine by themselves.
User avatar
leonardoliveira
Posts: 539
Joined: August 30th, 2012, 5:53 am
Location: Brazil
Initials: leo

Re: Ghosts n Goblins with 4 faults

Postby leonardoliveira » June 23rd, 2015, 5:31 pm

Are CPS2 A boards more common than CPS1 ?

They kind of have the same custom chips (CPS2 has custom chips that are unique to it in addition to the same custom chips CPS1 has).

I have a CPS1 A board but no B or C boards to go with it. D:
Image
User avatar
Rossyra
Supermod
Posts: 9378
Joined: February 12th, 2009, 1:24 am
Location: UK

Re: Ghosts n Goblins with 4 faults

Postby Rossyra » June 23rd, 2015, 7:37 pm

cps2 are more common by a country mile. Cps1 fail a lot more, I blame the exposed pcb and the crappy Fujitsu components
Image
User avatar
leonardoliveira
Posts: 539
Joined: August 30th, 2012, 5:53 am
Location: Brazil
Initials: leo

Re: Ghosts n Goblins with 4 faults

Postby leonardoliveira » July 6th, 2015, 3:11 am

Rossyra wrote:cps2 are more common by a country mile. Cps1 fail a lot more, I blame the exposed pcb and the crappy Fujitsu components


There were no such thing as "crappy fujitsu components" in 1990.

Fujitsu fixed their stuff in 1987/1988 when they discovered that the plastics on the chips casings were eating the metal out.

But yeah you're right about the exposed PCB part.

CPS1 would be far more common if it wasn't such a great target for bootlegging. CPS2 are more common simply because no bootlegger were man enough to fight with it.
Image

Edit: I just remembered that the two big CPS customs were made by Ricoh, not Fujitsu. The "A" one even has a Ricoh IC code stamped in it: "5C57".

But then, CPS2 has a ton of Fujitsu chips on it.
Image
User avatar
Rossyra
Supermod
Posts: 9378
Joined: February 12th, 2009, 1:24 am
Location: UK

Re: Ghosts n Goblins with 4 faults

Postby Rossyra » July 6th, 2015, 11:12 am

There are still a ton of Fujitsu components on the a-boards I've had over a few different pcb revisions, they still suck balls imo. No smoke without fire and all that ...

Was it a rhetorical question? You seem to have just answered it yourself anyway. Still, maybe CPS2 will become less common now there is a "bootlegger man enough".
Image
User avatar
leonardoliveira
Posts: 539
Joined: August 30th, 2012, 5:53 am
Location: Brazil
Initials: leo

Re: Ghosts n Goblins with 4 faults

Postby leonardoliveira » July 6th, 2015, 3:38 pm

Rossyra wrote:There are still a ton of Fujitsu components on the a-boards I've had over a few different pcb revisions, they still suck balls imo. No smoke without fire and all that ...

Was it a rhetorical question? You seem to have just answered it yourself anyway. Still, maybe CPS2 will become less common now there is a "bootlegger man enough".


I doubt it, because instead of killing a ton of them to make desirable games, people will be killing only one to make a jukebox for themselves.
Certainly Chinese pirates have zero interest in making them now as the interest of actual arcade operators on them are nearly zero.

What about those NAMCO boards with 90% of Fujitsu chips in them? Fujitsu is a cool company, leave them alone. (lol internet meme suggested here)

All the customs but one on the B board are from Fujitsu.
Image

Return to “Repair Logs”



Who is online

Users browsing this forum: No registered users