Space Harrier issues : no more sounds...and GFX gliches! Need help!

[DarthNuno]

Since few weeks, no more sound on my beloved Space Harrier! 
The last game before the failure, the sounds started to be like strange noises : the pcb played strange tones sounds, or a part of a sound, or a sound with the pitch too high, or too low... or even trying to speak like Q*Bert.

I don't think it's an amp problem, I mean this board... 



... because now that the game produces no more sound, if I turn the volume pot, I can hear the 'white noise/no sound' going louder... so I presume it is still able to amplify a signal, but I'm affraid the SH game board is no more producing any signal... 

Well, during my investigation, for a first visual check up, I had to remove the metal cage around the SH pcbs...



...to see where the sound signal is coming from, which I believe it's coming from the down/left connector from this board 



But, after that visual inspection, the next power on gave me this new problem   



A line of glitch on every sprites!
This looks like a bad ram?
So I went to the test mode of the game, and the rom/ram test gives me no error. I presume the test mode check only the ram used for the game program, but maybe not for the video ram? I don't have schematics and don't really know where to start.
Of course I checked the voltage, which is fine. I tried to increase it a little bit but it doesn't affect the graphic glitches on sprites.

Any good advice for :

1. The 'no more' sound problem?
2. The graphic glitches on every sprites ?

 

[Etienne MacGyver]

looks like the schematics can be found here :

http://www.crazykong.com/manuals/SpaceHarrier.sch.pdf

hope that helps, otherwise, i have no idea..

yeah, "replace pcb" but that is not an option in this situation i assume 

[Q*ris]

The ribbons are the source of many problems, at least that's what Inlearned from my Berzerk and my TRON.
Maybe double check if they are well seated?

[DarthNuno]

Maybe double check if they are well seated?

Yop, after re seated the inter-connectors boards ribbons, no more GFX garbage   



...but after more work on the boards, I've lost again the garbage-free picture  I don't know... maybe bad ribbon connectors?  I'll clean them or maybe change them...

Back on the 'no more sound' problem.
I want to know if it's a Space Harrier board problem or if its a Amp PCB problem.
So let's test that small amp board 



...and one ore use for my belove iPhone  Let's use it to send music signal to the amp board 



It works. My Space Harrier is now playing Dream Theater, and both channel are working! So this board is perfectly working.
My sound problem must be located on the Space Harrier board itself then!

Here's -I believe- the part of board where the sound is managed :



What test could be done here? Should I change 'blindly' these capacitors? or other components?

[level42]

I know nothing about such "modern" boards ( ) but....I see the MF6CN-50 chips are socketed so you could swap both just for the heck of it...
I googled them and they are filter chips. Probably not your problem but since they are socketed worth a try.

IC57 is a digital->analog converter.

Aren't there any build in tests for the sound by the way ?

[DarthNuno]

I see the MF6CN-50 chips are socketed so you could swap both just for the heck of it...
I googled them and they are filter chips. Probably not your problem but since they are socketed worth a try.

Had the same idea, but simply didn't do it because I don't have a chip extractor tool and no enough room to use a screwdriver to substitute. Because they are two filters (MF6CN-50), can we assume each one is for each audio channel? Anyway, as you say is an easy check and worth a try. I'll do when I'll have the extractor chips tool.

IC57 is a digital->analog converter.

Hey, yes, that could be the bad guy here... that would explain the strange noise I got from time to time... but as I said, 95% of the Space Harrier uptime, there's no sound at all...
Is there an easy way to test it? Or I can change it directly... will check if I can find this one for sale!

Aren't there any build in tests for the sound by the way ?

Yes, there is a sound test menu, when I can play each sounds/musics of the game... but no sound produced 

[level42]

Mmm, yeah I presume the filters are for both channels, at least I think it has Stereo sound right ?

Following this, it wouldn't be logic for them to be the cause, you'd expect one channel to have problems not both.

I absolutely HATE IC extractors and never use them !!!! They kill ICs IMHO

Looks like plenty of room for a small flat watchmaker's screwdriver. You can insert it in an angle and then twist it a bit, and/or use the chip on the left as a rest.....hard to explain in words/English.

Replacing the DAC would be a shot in the dark. If you'd have a scope and the pin outs you could try to trace back through the filters and DAC outputs to see if there's anything. But I'm sure there's more to the sound production going on...

[ajhippel]

there is a yamaha ym2203 sound generator.

the output of the ym2203 is tied together with the DAC output goint to the input of the op-amp
TL084 on 12J.

so if there is no sound at all it cant be the dac only...it must be somewhere here..

looking at the schematics there is a "mute"-line - through the 4066 that mutes both op-amps.

follow the mute line back to the source...maybe you'll find the answer somewhere there.

edit: the /mute line is generated on port PC0 on [i cant read the location] [See schematics page 2 upper left 40pin chip).
the /mute is an active low signal that is pulled low [to mute] by a resistor if no high-signal is coming out of the portc0.
It will be inverted by a ls04 on [can't read it either] going on to the connecter "N" on Pin [unreadable].
so if the mute signal is "high" on the 4066 (Pin 5 & 13) -> no sound...

Mmm, yeah I presume the filters are for both channels, at least I think it has Stereo sound right ?

Following this, it wouldn't be logic for them to be the cause, you'd expect one channel to have problems not both.

I absolutely HATE IC extractors and never use them !!!! They kill ICs IMHO

Looks like plenty of room for a small flat watchmaker's screwdriver. You can insert it in an angle and then twist it a bit, and/or use the chip on the left as a rest.....hard to explain in words/English.

Replacing the DAC would be a shot in the dark. If you'd have a scope and the pin outs you could try to trace back through the filters and DAC outputs to see if there's anything. But I'm sure there's more to the sound production going on...

[DarthNuno]

Thanks Jochen for these accurate explanations!  
I've printed the schematics on A3 sheets, and I read many times your analysis... and yes already learned some basis about reading schematics, localizing the IC on PCB...etc.
Well, yesterday I already (and stupidly) ordered few components (the dac and the m74h you can see on my picture) but yeah, there are many more components involved before... so if they didn't fix, I will really have to go to the next step... and use serious tools and really figure out how to use them ...  

[DarthNuno]

Well, got the first chip this week end : the M74HC4066B1 which is a QUAD BILATERAL SWITCH.
The original one on the Space Harrier is labeled M74HC4066. Hope the one I got (M74HC4066B1) has the same functions?



So I've just replaced the original M74HC4066 by the M74HC4066B1 on IC58 (and put by the same occasion an IC socket).

Plug the pcb game and ...



...nope... it doesn't fix the problem! On that video but can hear the strange sounds produced... it's wired, you can even recognize the sounds before they start to be crappy noises!

Well, I don't think to blindly replace components is a good idea... I had the hope... but ... maybe the next one will be the good one? Bhaaa! 

[DarthNuno]

OK, so got a new DAC1022LCN chip, the one located in IC57 



New one now in place (and of course I added a socket, while I'm here...) 



...and ...

No! Doesn't fix the sound issue!  This gonna be out of my knowledge I'm afraid... 

[ajhippel]

after listening to the video it seems that there is no problem with the sound-amps or switches..
it sounds more, that the "control" of the sound is not working properly.
it could be the connection from main-cpu to sound cpu or the complete sound-cpu section.

without measuring with a scope the only thing i can suggest is, try to clean the pins of the z80,the two 27128 eproms and, if socketed, the 2016 ram on the sound board.
maybe there is a connection issue.