Help! Game Board Repair (Super Pang)

[CHRIS-F]

Hi All,

I only bought my Super Pang (Bootleg) PCB a week or so ago and it worked normally, I removed my joysticks to clean out the gunk and swap a few Switches, everything worked with the machine open, I unplugged it and all I did was push the PCB back a little on top of it's plywood shelf and close the machine up, after switching it on again there was a horrible sound coming from the speaker and the screen showed a corrupt white screen with light blue blocks, I switched it off and on again and I saw a message saying RAM OK with lines across the screen, after switching it off and on again a few times I get different screens with corruption and sometimes the game seems to work, but there is no sound, about one time in ten it will start and work normal, sometimes at switch on it seems to be making corrupt sounds like in attract mode, but AFAIK attract mode sounds is off so it shouldn't be doing sound anyway until a coin is inserted, my initial thought was I may have pulled a solder point loose when sliding the board along the wooden shelf, but I can't see any loose.

Where do I go from here to try and diagnose the fault, I have a multimeter, (I think it has logic test) and I have checked I'm getting about 5.1V at the chips and just over 12V (forgot the exact voltage) but the voltages seem to be correct.

Thanks,
Chris.

[Mike A]

I am not an expert at this, but the first thing I always do when a board suddenly stops working is clean the edge connector and plug it back in. That has worked a surprising number of times. I have had two boards where I cleaned and re-seated any chips in sockets. That fixed them up. This would be a good starting point.

[CHRIS-F]

I am not an expert at this, but the first thing I always do when a board suddenly stops working is clean the edge connector and plug it back in. That has worked a surprising number of times. I have had two boards where I cleaned and re-seated any chips in sockets. That fixed them up. This would be a good starting point.

Thanks Mike,

I have cleaned the edge connector with a scotch pad and IPA and wiggled it on and off a few times, still no change, also I have re seated all the EPROMS. I'm leaning towards a logic fault maybe as the only thing that makes it work is powering it on and off a few times, each time is different but it occasionally works ok.

[Mike A]

Yeah. It is time to get down and dirty then. Pretty much anyone will know how to proceed better than me.

[opt2not]

It's possible you might have scratched a trace when moving it around in your cab.  I would go over it with a magnifying glass and look for scratches or gouges that might have torn traces.

Another possibility, shifting around an older PCB can sometimes knock the legs of the surface mount chips loose.  I've had this happen to my Smash TV board, when it was shipped to me. 
One way to check this is by turning the game on and tapping or lightly pressing on some of the surface mount components.  If you see a change on-screen, there could be cold solder on those components, or they're failing.

One last "physical" test you can try is light bending the PCB a bit when it's running. Sometimes these boards get flexed over time, especially if they're stored improperly (horizontal storage should be avoided as gravity will eventually make your PCB's sag).
If something changes on-screen while you're lightly bending the board, there is most likely a cold solder joint somewhere.

[CHRIS-F]

It's possible you might have scratched a trace when moving it around in your cab.  I would go over it with a magnifying glass and look for scratches or gouges that might have torn traces.

Thanks, will have a look over it tomorrow :-)

[CHRIS-F]

O.K. Here's what if done so far, I looked over the pcb with a magnifying glass, It's had some previous repairs a few chips have been socketed, and the solder was covered in crappy brown flux, I re soldered those socket pins and a few other suspect looking joint's, I took out all of the EPROM's cleaned the legs with one of those sanding sponges, and re seated them. there was no change it still shows the screen like in the above comment mostly white with blue square. sometimes it boots and sometimes not, I am only a beginner with electronics so don't really know what I'm doing, so I may have done this wrong but I checked the clock on both of the z80's my multi meter has hz and logic, I put the Black lead on ground at the jamma connector and red lead on pin 6 (clk) from memory the meter read 6mhz there is a 12 MHz crystal near by, I think the other z80 is for sound it's near the audio amp and I think that read about 3.75MHz there is a crystal near that that just says 10.000, I checked the 5v pin and that is correct then I checked the reset pin no 26 and one time it was stuck lo but most times it is high.

The interesting thing is if a take a piece of wire and short pin 26 (reset) to ground when I let go it resets and runs almost properly, but wether I reset it by hand or if it boots it's self there is some graphics corruption, when the letters from PANG move around the screen the colours are wrong and not solid they have vertical lines and they only go solid when they come to rest, the super bit at the stop stays messed up.

So where do I go from here? any suggestions, is it most likely two separate problems or could it be the same fault causing both?

Thanks,
Chris.

[CHRIS-F]

Anyone know how to proceed with getting this board working? I noticed something weird also, if I plug the machine in it usually doesn't boot properly, but if I pull the jamma edge connector and re seat it the game runs, where should I start looking for why it's not resetting properly, could it even be the z80, I may have a spare, then why are the colours messed up? it's supposed to look like the pictured insert below, when the pang letters are moving round the screen they are also weird colours and not filled properly until they stop moving. I saw a similar repair and it was a ram chip and another was a faulty eprom, I hope it's not an eprom as I have no way of testing/writing a new one.

I can post  a picture of the board layout if that helps.

Thanks,
Chris.

[Titchgamer]

Sorry I cant offer much in the way of useful advice on PCB repair.

But your comment about pulling and reseating the jamma connector is a good indicator that either the board contacts need cleaning or the jamma connector does.
Or a bad contact.

So maybe start with that?

I use WD40 electrical contact cleaner to clean all my game carts etc.

Just spray some on a cotton bud and give it a gentle rub then leave to dry.

[opt2not]

Yeha, wish I could help out too, but I don't know what's going on with those bootlegs. I have an original PCB of Super Pang with different sprite issues, and have an idea of where to look on my board, but I wouldn't be able to tell you what to look at on a bootleg.
On the original boards there are 2 major customs that deal with sprite generation.  If you could determine where the graphics generation circuit is located on your bootleg, I'd start probing IC's for stuck or dead logic on their data pins.

[CHRIS-F]

Your comment about pulling and reseating the jamma connector is a good indicator that either the board contacts need cleaning or the jamma connector does.
So maybe start with that?

Yeah! I thought it could be a bad connection, but I've cleaned it twice now and still the same, it doesn't boot on it's own but If I short pin 16 (Reset) on the main Z80 CPU it shows the ram ok and boots normal (apart from the graphics corruption), so I'm leaning towards a faulty reset circuit, I'm only a beginner with electronics so it's not easy to trace stuff, I tried to follow the reset line but it goes through a few through hole points and then I only got as far as the same pin on the sound CPU another Z80 and a little further to an ic, I checked the pinout of that IC but it's not something I'm familiar with so I gave up :-( I will try again this time taking note of the IC and writing it down.

[CHRIS-F]

Yeha, wish I could help out too, but I don't know what's going on with those bootlegs. I have an original PCB of Super Pang with different sprite issues, and have an idea of where to look on my board, but I wouldn't be able to tell you what to look at on a bootleg.
On the original boards there are 2 major customs that deal with sprite generation.  If you could determine where the graphics generation circuit is located on your bootleg, I'd start probing IC's for stuck or dead logic on their data pins.

I know this pcb differs quite a bit from a genuine Super Pang, but any idea where about to start looking? I would like to first fix the reset problem, the board wont boot by itself but resetting it by grounding pin 16 on the cpu gets it running, I'm Guessing something is being stuck hi/low just don't know where to look.

Thanks,
Chris.

[CHRIS-F]

It's possible you might have scratched a trace when moving it around in your cab.  I would go over it with a magnifying glass and look for scratches or gouges that might have torn traces.

Another possibility, shifting around an older PCB can sometimes knock the legs of the surface mount chips loose.  I've had this happen to my Smash TV board, when it was shipped to me.

One last "physical" test you can try is light bending the PCB a bit when it's running. Sometimes these boards get flexed over time, especially if they're stored improperly.

You were only right :-) Moving the board had moved a trace that was lifted, not only did it move but it had broken in two, I only found this after killing two CPU's :-( I also found a dry joint and a few areas on the board where previous repairs weren't done so well, some of those traces run really close to IC pin solder pins and the crappy flux was all over the area, the protective covering is also missing on some traces, I had a hard time tracing the reset circuit as it runs under soldered in IC's, but eventually found the Ceramic resonator has had legs soldered on and was only touching intermittently, ordered a new one from the USA but in the meantime it's bodged.

I'm now Happy that my board is working properly and as a bonus I even figured out the dip switches although I can't notice any difference selecting Easy, Hard, Very Hard, Normal :-)

A further question though, is it normal for some of the IC's to get warm/Hot? I noticed a few get quite warm, I might get a thermocouple on and see how hot and which particular chips, its possible that there may be some more shorts somewhere on the board unless it's perfectly normal for them to get hot.

Thanks again everyone for your help.

[Titchgamer]

Well done figuring it out.

And yeah its normal for IC’s to get warm.

[opt2not]

Nice job on the fix! These fixes are the easy ones, you’re lucky you didn’t have to replace IC’s. I wish all my fixes where like this.
Glad this got sorted. 

[CHRIS-F]

It looks like my victory was short lived :-((

My youngest son was playing it for a while and the sound went funny, most of the sound works but it sounds at though one of the channels has gone down, and when I tried it again today its making some noises when starting up that shouldn't be there and failed to boot again, I just don't know where to look for an intermittent fault like that.

could the missing sound problem be the LM324A maybe? if so where can I get a replacement? can I trust the ones on ebay? also could it have something to do with the M5205 again can I trust the ones on ebay manufactured in Thailand? could it even be the YM2413?

I'm sorry I bought the board now it must have been cheap for a reason, my problem is the board is not even worth the hourly rate for someone who knows what their doing to look at it, I don't really have a clue :-(

If those few chips are not to be trusted from ebay, where can I find alternatives in the uk?

Thanks,
Chris.

[opt2not]

You could start by replacing the caps in the audio circuit.  They're usually all clustered together.  By the looks of your previous picture, the top-left section looks to be the audio area.
Given that this is a bootleg, there aren't going to be any hard to obtain custom IC's you need to worry about. So I would just try to rebuild the audio circuit, simple components at a time. 

[yotsuya]

Try the sound amp chip. I’ve replaced two of those on different boards and that solved sound issues

[Mike A]

That fixed my vanguard board.

[CHRIS-F]

Try the sound amp chip. I’ve replaced two of those on different boards and that solved sound issues

Which one is the sound Amp? the LM324A or do you mean the actual amplifier which looks like a Voltage regulator TDA something or other? I was thinking the LM324A as it's a quad op amp and that would make sense if it's amplifying 4 separate channels and one has gone down, but if the TDA amp has died there wouldn't be any sound would there?

Thanks,
Chris.

[CHRIS-F]

Looking quickly over the board each of the quad op amps of the LM324A has a 10uf cap and a small ceramic blue cap marked 104, it looks like someone has worked on it before, 3 of the 10uf caps are smaller and one bigger, one of the blue caps has been replaced with a brown substitute which is labelled 102 which I assume is ok but the cap at C11 looks a little suspect to me it looks like it reads 422 and it had a strange white coating on it I only saw the value when I scraped it off, anyone else have the same bootleg board and can confirm this cap is right or it should be a 104/102? also most of the caps on this board are 10uf but the very bottom left cap is 100uf again is that correct?

Thanks,
Chris.

[Titchgamer]

Ile have a look at mine tonight when I get home if nobody else gets back to you.

[Titchgamer]

Ok so my cap at C 11 is a 682k
And I dont have a cap at all at C 19

Hope thats some help!

[CHRIS-F]

Ok so my cap at C 11 is a 682k
And I dont have a cap at all at C 19, Hope thats some.

Yeh Thanks, much appreciated :-)

 I may have to give up on this board though and buy another :-( I was working in bad lighting last night and I was checking voltage at the pins and I accidentally shorted something, not exactly sure which IC I touched but I think it may have been the 74LS368AN IC ( all the graphics corrupted on the top half of the screen and it froze, after a power cycle nothing just a white screen and resetting the cpu does nothing, just wondering if it could have killed the CPU or the 368 not really sure where to start looking now.

Any Ideas how to start diagnosing the fault?
I could check for a clock/voltage at the cpu but after that I'm lost.

Thanks.

[Titchgamer]

Oh that sucks

[Mike A]

The first step is to buy a lamp. You shouldn't be doing this kind of work with bad lighting. Besides wrecking PCBs you wreck your eyes.

[CHRIS-F]

The first step is to buy a lamp. You shouldn't be doing this kind of work with bad lighting. Besides wrecking PCBs you wreck your eyes.

Yeh lesson learned, wont be doing that again, sad thing is I have a nice CCFL lamp with adjustable stand for this very reason, and I normally have my reading glasses on, it was a just a stupid moment, I wasn't even working on the machine I was just walking past it and thought "I know check the psu voltage the 12v might be too high/low" I quickly powered it up didn't have my glasses on and no lamp plugged in my meter was already there :-(

[Mike A]

I think everyone has done something like that. You are in good company.

[CHRIS-F]

I seem to be running into more and more problems with this board, In MAME it says Super Pang world bootleg uses two Z80 CPU's at 8Mhz, I think I have seen more than one type of S-Pang bootleg so that may explain it, but when my board was working and I checked pin 6 the clock pin on both my CPU's this is what I got;

Z80 CPU near the Sound section (ZILOG Z0840006PSC - 6.17Mhz ) running at around 3.75Mhz (ok as its underclocked)
Z80 CPU (Main one I think) (MOSTEK MK388ON-4) running around 6Mhz

I didn't give that another thought until I killed two CPU's one after another with that lifted trace, now I've come to find a few spare CPU's and I thought I'd either try and find a couple of 8Mhz CPU's or just replace them with the same type if I could find them but that one I believe to be the main CPU at the bottom of the board seems to only be a 4Mhz Mostek, although the game seemed to work fine, am I going crazy, surely it couldn't have been running overclocked by 200Mhz?

So with that in mind what type of CPU should I source for spares/replacements? will it matter if they are NMOS/CMOS etc and anyone know of a reputable source in the uk?

Thanks again.

[Titchgamer]

Dude, At this point in time I think you are better off just getting a new board.

Dont get me wrong if your having fun and learning crack on but if you want to actually play the game for what its going to cost you in time and money its scrap.

After all its only about £30 to get a replacement.

[CHRIS-F]

Dude, At this point in time I think you are better off just getting a new board.

Dont get me wrong if your having fun and learning crack on but if you want to actually play the game for what its going to cost you in time and money its scrap.

After all its only about £30 to get a replacement.

Yeh! I'm really enjoying learning a bit about electronics as I go, I don't want to be defeated by it lol, I'm sure I just killed one of the IC's when I shorted it, I intend to buy a few more games in the near future, but would like to do a bit more learning before I try to tackle a monitor recap/repair :-)

Funny thing is my pcb feet arrived today if I had them in the first place the first short caused by the lifted trace probably wouldn't have happened.

[Titchgamer]

I think a recap is probably much easier than what you are trying to do atm lol

But I have a faulty tekken 2 board I can sell you if you want to tinker lol

[CHRIS-F]

I think a recap is probably much easier than what you are trying to do atm lol

But I have a faulty tekken 2 board I can sell you if you want to tinker lol

Not really my cup of tea Tekken, but thanks for the offer :-)

Now for the good news, I suspected the 74LS368AN at IC 13 was somehow faulty as there was no clock on the main Z80, I traced the clock signal back to IC 13 and it was in the same region as the IC where my test probe slipped, I removed the IC carefully and lo and behold I found a burnt out trace on pin 15, I must have slipped and shorted 5v to Gnd, I fixed the trace and fitted a socket, I ordered a new IC already and I really didn’t expect it to work again as I had to heat it up a good few times to remove it, but I was really surprised when I tried it and it worked, I also replaced the oscillator and it seems to be working fine again, just need to sort the small sound problem out next :-)

[CHRIS-F]

Little Update:

I am happy to report my board is now working 100% thanks to a Z80 hardware guru in the ZX Spectrum community, who helped me trace a problem in the reset circuit, which also fixed the odd sound problem, I guess the reset wasn't initialising the Yamaha YM 2413 and the OKI M5205 synth chips properly, I did make a few Noob mistakes and make this board worse in the first place but I don't mind as I've learned a bit in the process:-)

So what have I learned;

1. Use those little plastic PCB feet to stop any board damage moving the board around in the cab or on a bench.
2. don't trust old electrolytic capacitors even if the capacitance looks ok.
3. don't use test equipment in the dark/bad light.

The main problem was the two electrolytic capacitors in the reset circuit, they both tested ok in my Chinese component tester (capacitance wise) but after replacing them, the board now boots every time and the sound is correct :-)

[Mike A]

Glad to see you got things up and running.

[Titchgamer]

Fair play mate well done! 

Now dont break it again!! 

[CHRIS-F]

Now my board is working nicely, I cleaned it up a bit today and replaced all the electrolytic caps, the sound has improved a lot, I'm just wondering if anyone else has one of these boards does your level select work in Tour mode? (by holding the joystick down when selecting Tour mode), when I enter the level select, the game is still running, but there is no Asterix, and I can't get out of that screen, it doesn't crash as the music is still running and player 2 can join but I just get stuck with no way out or to select a level. I am assuming it just doesn't work as it's a bootleg. but would appreciate if anyone can confirm this?

Thanks,
Chris.

[CHRIS-F]

Anyone have this Bootleg version, and know if the level select works in tour mode? I need to know if it's just because it's a bootleg or if it is another problem on my board, I also have a second problem which is not so bad really but I wouldn't mind getting to the bottom of it, when I turn my machine on the sound is playing up again, sounds like one of the channels isn't playing correctly but once the machine is warmed up it sounds ok, what am I possibly looking at here, I have replaced all the electrolytic caps so don't think it's that and fixed the reset circuit so I think the Synth chips are being reset properly, possibly a voltage problem?

Thanks,
Chris.

[issalig]

Hi, I have a similar board (also bootleg) but it has and addon board with a z80, rom and some more things.

The problem is that C4 and C5 capacitors are missing (bottom left in the image, at the right of jamma connector) and it resets continuously. Could you please check the values and report it?

Thanks in advance.

[CHRIS-F]

Hi, Sorry, I only log in from time to time, only just saw your question. I just had a look, they are both marked 101, I'm only an amateur with electronics but I think they are 100pf ceramic disc caps, hope that helps.

I took a picture, but apparently my image failed security checks, it was displaying all squished so I cropped the image and now I can't upload it :-( anyway they are definitely marked 101 with a line beneath :-)

Regards
Chris :-)