Bootleg Ghouls n' Ghosts with buzzing sound.

[daeds]

Hey there good people,
Today I fired up my bootleg GnG board and I almost cried, it's buzzing as all hells!
It was stored for a while, it was, but c'mon!
I've checked for leaky caps, tried to force all the slotted chips, looked for cold solder joints, nothing, at first glance.
How can I start looking for the culprit here?
You can still hear the ingame sound and the buzzing goes up and down with the volume pot, it kind of changes for example when Arthur fires his spear,
This is the board:

Looking forward for all your good advices!
I've tried other boards and they are all OK.
Thank you.

 

[TheDaddy]

Could be basically anything !! If your getting buzzing then amp is working , could be an issue with ROM but you normally get a bit of something , caps maybe , cpu (prob a Z80). I would be looking at the RAM first.

Its down to scoping / probing now realy. Do you have an Audio probe ?

In my opinion Audio faults are the worse ! So annoying !! I have a few on the ' to hard pile '. Need to start gng in there again.

Dave.

 

[daeds]

Could be basically anything !! If your getting buzzing then amp is working , could be an issue with ROM but you normally get a bit of something , caps maybe , cpu (prob a Z80). I would be looking at the RAM first.

Its down to scoping / probing now realy. Do you have an Audio probe ?

In my opinion Audio faults are the worse ! So annoying !! I have a few on the ' to hard pile '. Need to start gng in there again.

Dave.

Hey Dave, thanks for your help,
Sadly I don't have an audio probe but I can make one I, I've seen some easy ones around I guess? Any easy one you recommend?
And yeah, so annoying,
For now I have a multimeter, a logical probe and nothing more (apart from the soldering tools).
Damn PCB, I really wanted to have a pint and blast some rounds today...

 

[TheDaddy]

Use logic probe on the audio ram , probably a 2016 or something. Grab a pinout and check imputs and outputs , then do the same with CPU , make sure its not being reset or on holt.

Dave.

 

[Martinmurphy30]

Hard to make out in the photo but are the legs of the amp bent and touching? The small capacitor at a wonky angle looks suspicious also. Are the roms on this board socketed? I cannot find a bootleg ROM set for ghouls 'n ghosts anywhere....and the PCB layout looks very similar to street fighter ii ce

 

[daeds]

Use logic probe on the audio ram , probably a 2016 or something. Grab a pinout and check imputs and outputs , then do the same with CPU , make sure its not being reset or on holt.

Dave.

Where should they be Dave? I'm a bit clueless and kind of new to all of this and can't find schematics for this, the CPU is the z80 and it's socketed, hopefully something's wrong there and I can piggyback another one (if possible ofc).

 

[daeds]

Hard to make out in the photo but are the legs of the amp bent and touching? The small capacitor at a wonky angle looks suspicious also. Are the roms on this board socketed? I cannot find a bootleg ROM set for ghouls 'n ghosts anywhere....and the PCB layout looks very similar to street fighter ii ce

Hey!
I think that the ROM are not socketed, but as a newbie I can't tell for sure, I do have some socketed chips, the CPU for example.
The amp legs are bent but not touching, it worked well like 2 weeks ago.

 

[Georgian2]

Hard to make out in the photo but are the legs of the amp bent and touching? The small capacitor at a wonky angle looks suspicious also. Are the roms on this board socketed? I cannot find a bootleg ROM set for ghouls 'n ghosts anywhere....and the PCB layout looks very similar to street fighter ii ce

Maybe an street fighter bootleg converted to ghouls and ghost? could be interesting.

 

[daeds]

Maybe an street fighter bootleg converted to ghouls and ghost? could be interesting.

What a frankenstein I have here! No wonder why it buzzes like a portal to the lands between. :| It played so well two weeks ago. I'm soooo mad, it was my favorite game.

 

[TheDaddy]

Where should they be Dave? I'm a bit clueless and kind of new to all of this and can't find schematics for this, the CPU is the z80 and it's socketed, hopefully something's wrong there and I can piggyback another one (if possible ofc).

I can see it but in bed at minute so i will look tomorrow when at work and cirle the ones to check.

If you coukd take a few better pics of the audio section including a slightly more side view (if that makes sense !)

I woukd remove the cpu , rom (looks socket as seems higher than othersbut cant tell by pick) Clean legs , ipa and regit as well.

Dave.

P.s strange board indeed !

 

[daeds]

I can see it but in bed at minute so i will look tomorrow when at work and cirle the ones to check.

If you coukd take a few better pics of the audio section including a slightly more side view (if that makes sense !)

I woukd remove the cpu , rom (looks socket as seems higher than othersbut cant tell by pick) Clean legs , ipa and regit as well.

Dave.

P.s strange board indeed !

Will do that and will post some photos tomorrow for you to have a better look at it, thanks everyone for the awesome support, hopefully will be able to get this one back to it's former glory!

 

[TheDaddy]

I have a fully working conversion on original hardware for aale if not ! Lol.

Dave.

 

[Martinmurphy30]

I would be interested in dumping the roms on this out of curiosity as I cannot find a complete bootleg set. If you'd be interested in posting it to me I can try and repair it at the same time?

 

[daeds]

I have a fully working conversion on original hardware for aale if not ! Lol.

Dave.

I fixed it today! Fired the logical probe (for the first time) and checked the YM chips for stuck pins, then I removed all the socketed chips and cleaned both with contact cleaner and IPA, done! Thanks a lot for your help Dave!

 

[daeds]

I would be interested in dumping the roms on this out of curiosity as I cannot find a complete bootleg set. If you'd be interested in posting it to me I can try and repair it at the same time?

Hey Martin!
I actually fixed it today (check my last post here), it was but some gunk on a chip socket for sure,
I would happily post it to you someday though I'm from Portugal and the customs are a PITA and I'm scared of it getting borked to be honest haha, where are you from?
Thanks a lot!

 

[TheDaddy]

I fixed it today! Fired the logical probe (for the first time) and checked the YM chips for stuck pins, then I removed all the socketed chips and cleaned both with contact cleaner and IPA, done! Thanks a lot for your help Dave!

BANG !!! Yeh great news . Glad we could help.

How satisfying was it when you fired it up and it worked ?? There is NO better feeling !!

Dave.

 

[daeds]

BANG !!! Yeh great news . Glad we could help.

How satisfying was it when you fired it up and it worked ?? There is NO better feeling !!

Dave.

That's true! I love electronics and I'm always pleased to learn something new,
My first fix was actually a Toki Bootleg board that had a fair share of problems, had to change the crystal for it to actually sync with my TV (I use CRTs and a jamma converter) and it had a problem with the sprites (well, actually still kind of has the problem but it's mostly fixed upping the voltage).
Happy days!

 

[Martinmurphy30]

Hey Martin!
I actually fixed it today (check my last post here), it was but some gunk on a chip socket for sure,
I would happily post it to you someday though I'm from Portugal and the customs are a PITA and I'm scared of it getting borked to be honest haha, where are you from?
Thanks a lot!

Excellent work! Great feeling when a fix works! I'm in northern Ireland, and yeah customs can be a nightmare. I will stick a wanted post up as I cannot believe this has not been dumped, every other bootleg cps1 ROM is available!

 

[daeds]

Well, bad news, my victory was but temporary! It's doing the same noise again.
I'm almost sure it's the YM3012 (KA12) chip, when I touch the ground pin and the other pins sometimes the noise goes away, until I turn it off and let it "cool",
What can I do but replace it?
Seems hard to come by, damn conversions!

 

[TheDaddy]

Maybe take Martin up on his kind offer ??

Dave.