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Ghosts'n Goblins (original) repair

yavuzg

yavuzg

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Hello everyone,

I know there are plenty of repair logs out there related to this highly sought after arcade classic Ghosts'n Goblins, either original or bootleg. But I decided to write my own experience with my recently purchased GnG PCB repair since I couldn't find a repair log specifically related with the problem I had.

Anyway, here it is...

I bought this PCB from ebay. It was listed as untested and the auction was going well for a while but someone decided to enter a pissing contest with me and the price went up beyond my calculated budget for an untested GnG. So I just left the auction...

Then, a week later the seller made me an offer saying that the winner didn't pay. I accepted the offer and here it is sitting on my test bench :)

IMG_4555.jpg

I already got a Capcom Classic to JAMMA adapter from my spare Commando PCB so I immediately plugged it and switched the power hoping the best for this "untested" board would come up...

Aaaand, action!...

IMG_4556.jpg


Well, life is never that easy :(

A completely dead board. How nice!

You know, sometimes I prefer a completely dead board because most of the times the problem is so simple to solve. But this time, I was a bit nervous because this is my first GnG PCB, never had a chance to work on a GnG before and I don't even know if it has unrepairable custom chips on it or a massive hidden track corrosion etc...
 
Anyway, soon the disappointment passed and I moved on...

The first thing I checked was the CLOCK pin of the Motorola 6809 CPU.

IMG_4557.jpg


And the scope showed a dead CLOCK signal. That's good news ;)


IMG_4558.jpg


My next stop is the 12Mhz crystal. Checked it with my scope and it was dead also. A faulty crystal is not so common thing (but seen a few). Generally the culprit lies in the surrounding circuitry, the oscillation tier.

Anyway, downloaded the schematics and start reading some repair logs. After reading couple of repair logs and reading the schematics, I suspected the 74LS04 sitting right in the middle of the oscillation circuitry.


IMG_4565.jpg



Desoldered it and tested out of circuit...

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Aha! Found the bastard... Replaced it and fired the PCB again...

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Now we are in business :)

But was it all? Of course not! This untested PCB still has some more surprises for me ;)

Noticed the vertical lines on Arthur and zombies? That is our next stop in this repair journey...
 
The glitch on the sprites was not so weird at first glance. It was not effecting the spirtes majorly and at first glance it might be simply a ROM/data bus related issue (Notice the red vertical line on Arthur's sprite and the messed up colors on the zombie...


IMG_4589.JPG


I suspected bad EPROMs and dumped all the EPROMs and checked with ROMident. They all checked out OK. Infact this is a normal GnG US set which is already in MAME.

Moved on and checked all the sprite RAMs. According to the schematics, 6 x 2114 SRAMs (1024 x 4-bit) are responsible with the sprites on the bottom board. My programmer (TL866) cannot test 2114 SRAMs and I don't have any spares in my parts drawer. BUT I do have a spare knwon working Capcom Commando PCB from that same era. Checked it and yes, it does have 2114 SRAMs also. Unsoldered one and used as a test substitute.

IMG_4578.JPG


Piggybacking didn't helped, scope was not showing weird/missing signals either but these methods are not definitive troubleshooting techniques. They sometimes work but to be sure you have to get your hand dirty ;)

Socketted all the SRAMs and tested one by one...

Unfortunately a total waste of my one hour. All the SRAMs were OK.
 
Check and eventually replace the Fujitsu TTLs near the 2114 RAMs especially the 74LS157 and 74LS245 (I guess they involved in address and data lines of he RAMs).
 
After the shotgun technique I used on SRAMs, I decided to be logical and continue reading the schematics. I begin to test all the components in-circuit following the address and data bus related with sprites. I noticed one label on the schematics called OBHFLIP.


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Hmmm that's interesting since when I move Arthur to the right, I see a single red vertical line as a glitch but when I move him to the left, the colors are completely messed up.

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I then thought, these graphics may not have individual data in the EPROMs since memory was expensive in 1985 and to save up space they may have designed the circuit in a way to re-use the same graphics data by "flipping" the sprites ;)

And, the OBHFLIP signal might as well "Object Horizontal Flip"?

I decided to follow that path on the schematics.

I checked the 74LŞ174 on location 10J in-circuit with my scope and it seemed working fine. Although the OBHFLIP signal seemed a bit un-healty. Not much distorted but having a few weird ripples...

Then I followed where it goes and ended up with a 74LS257 at location 5K. This is a multiplexer and sitting right in the middle of the graphics ROMs and the selection pin is tied to the OBHFLIP signal! Moreover, the color data are selected and relayed by this multiplexer...


IMG_4613.JPG




I checked all the pins and the signals were really looking un-healty (notice the dragged down signal edges like melted wax? Indication of an internal short, not totaslly related with that pin but manifesting itself by in capable of maintaining correct voltage levels etc)...

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Removed it and tested out of circuit...


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Replace it with a new one. Fired up the board once again...
 
Last edited:
BRAVO!!!!I guess the TTL was from Fujitsu.Now let's sell the board on Ebay to make profit...
 
caius said:
Check and eventually replace the Fujitsu TTLs near the 2114 RAMs especially the 74LS157 and 74LS245 (I guess they involved in address and data lines of he RAMs).
Click to expand...
Yes those were my first suspect. They were heating alot but scope showed no sign of missing/stuck signals on them...
caius said:
BRAVO!!!!I guess the TTL was from Fujitsu.Now let's sell the board on Ebay to make profit...
Click to expand...
Noooo... For years I always wanted a GnG in my collection. When I was a kid, I used to play the Commodore 64 version of this game for the whole summer holiday. I was totally pissed of because the game was so hard but continued to play it anyway I don't know why...

GnG is my childhood trauma :P I'm going to keep this bastard :D
 
Excellent troubleshooting and repair! Ive had a glitching Ghosts N Goblins sitting in my To Repair queue for a while as well. I'll definitely refer back to your thread when I finally tackle it.
 
caius said:
Sure maybe he is so good thanks to our repair logs on JAMMArcade :) We are teaching a lot of people how to become a repairer from scratch :)
Click to expand...
I agree 100%. Jammarcade is "the" main source I first check and your repair logs and pal dumps helped saved many of my PCBs. I'm just trying to be your humble apprentice sir ;)
 
@yavuzg the bidder that didn't pay sounds to me like "I was bidding on my own auction but was so greedy that I won it", now I offer it to you so I can still get a high price X(

Anyways lovely repair. Congrats! I love this game but makes me angry when after reaching level 4 or 5 I get killed and have to start again. I think I'll change the program to me for a version where you have unlimited lives or something like that :D
 
Darksoft said:
@yavuzg the bidder didn't pay sounds to me like I was bidding on my own auction but was so greedy that I won it, now I offer it to you so I can still get a high price X(

Anyways lovely repair. Congrats! I love this game but makes me angry when after reaching level 4 or 5 I get killed and have to start again. I think I'll change the program to me for a version where you have unlimited lives or something like that :D
Click to expand...
Could be... In any case, I paid what I thought I would willing to pay, so I'm ok with it. I don't expect much from my ebay purchases generally anyway.

The main reason of my disappointment when I first realized that I got a dead board is that when I accepted the offer and paid, someone on KLOV just dropped in two working GnG PCBs for sale... Glad that I managed to fix this otherwise I'd be totally pissed with myself :P
 
good job buddy, i had a similar error on one of my gng's, the oscillator had one broken leg so that took care of the non-booting issue. then i had grapchial errors in the sprites, kinda like your pcb. but it was due to oxidized sockets on the video board. replaced them all and after that, the pcb is 100% :)
 
yavuzg said:
I then thought, these graphics may not have individual data in the EPROMs since memory was expensive in 1985 and to save up space they may have designed the circuit in a way to re-use the same graphics data by "flipping" the sprites ;)
Click to expand...
All consoles and boards make use of sprite flipping, it would be stupid not too if sprites are intended to be symmetrical, even if memory space wasn't an issue.
BTW congrats on your repair. :)
 
you will find it better than the c64, the c64 has less levels because the programmer was a lazy bastard who didnt play the arcade game through.
i know this because i met him once!!!

also i'v played both the c64 and arcade versions through.
 
And the music in the c64 version? Why did they do that? The original was so cool!!!
 
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