Toki Bootleg - No sound.

D

daeds

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Hello there fellow arcade enthusiasts,
I've been wandering around most forums to try and get my Toki bootleg board repaired and I just found out about this forum, :)
I received the board yesterday and it had it fair share of situations, the second board connection was broken and it seems someone was playing football with the box,
Anyways, to the problem,
I don't see any broken traces or blown caps, I've retouched the sound pot solder and it doesn't make a sound,
Even when I touch the amplifier or the opamp, or the caps, no noise is heard, same with the pot,
This is the board and it's sound circuitry:
1.jpg
2.jpg
I'm new to all of this and learning electronics, I don't have a logic probe yet and I've been trying to understand how all of this works but I really need a helping hand,
Thank you!
 
Jacmar

Jacmar

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Yes could be it needs -5v, or the amp is blown (not sure what's going on with the heatsink it looks charred)
but you could really do with something to probe signals ... ideally an oscilloscope
 
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daeds

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Jacmar said:
Yes could be it needs -5v, or the amp is blown (not sure what's going on with the heatsink it looks charred)
but you could really do with something to probe signals ... ideally an oscilloscope
Click to expand...
Yeah it looks like painted black, really weird, it gets very very hot to the touch though, is it a good sign?
I still don't have an oscilloscope, I'm really new to repairing stuff, well not repairing in general but these complex things yeah.
Anything else I can try taking a look? The logic probe comes next week.
 
Jacmar

Jacmar

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It's normal for an amp to get warm/hot, but very very hot is not usually good.
You could make an audio probe ... that would tell you if its the amp that is knackered ...
 
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daeds

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Jacmar said:
It's normal for an amp to get warm/hot, but very very hot is not usually good.
You could make an audio probe ... that would tell you if its the amp that is knackered ...
Click to expand...
Yup, got to see if I have the parts for that indeed.
Any other stuff to be looking for? Without the probe and the oscilloscope?
The board has some garbled sprites when the characters are moving, not a lot but some garbling, I guess that would be another adventure. :)
 
sukhbir

sukhbir

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The amp normally runs hot,the heatsink is oxidised but it looks ok.
As this is a booty it may not be jamma standard,the original is jamma.
Possibly the audio out at the games edge connector is wrong,I had a similar issue with a galaxian booty with no sound .
 
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daeds

Newbie
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sukhbir said:
The amp normally runs hot,the heatsink is oxidised but it looks ok.
As this is a booty it may not be jamma standard,the original is jamma.
Possibly the audio out at the games edge connector is wrong,I had a similar issue with a galaxian booty with no sound .
Click to expand...
The guy that sold the board to me had it running with a jamma harness and all was working, but it was in a proper cab, not a supergun. :\
As it was wrecked in shipping now he said it worked, I trust it did, but I never know,
How can I check that connector? Continuity between the amp and the speaker pins on my supergun for example?
Thank you so much for all your help.
 
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daeds

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I actually fixed it by looking at the amp and trying to check for continuity between pin 1 of the amp (output) and the pin 10 of the connector and as soon as I touched the pin 10 the sound works...? I'm in awe right now, can I just pass a bodge wire directly to the connector and we're done? Thanks a lot!!! I'm so happy.
 
sukhbir

sukhbir

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Good news (y), that means pad 10 is floating.
Without powering the game check the trace from pin 1 of the amp to pad 10 using a multimeter on continuity mode.
Where you find the break just bridge it with a wire and solder it.
 
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daeds

Newbie
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7CR
sukhbir said:
Good news (y), that means pad 10 is floating.
Without powering the game check the trace from pin 1 of the amp to pad 10 using a multimeter on continuity mode.
Where you find the break just bridge it with a wire and solder it.
Click to expand...
Oh yeah! :)
Now gotta fix the other problem, some lines in the sprites. It's not anything big big but it's noticeable, any tips for that one? I smell it's going to be harder.
 
sukhbir

sukhbir

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Lines in the sprites May be a bad graphics sprite Rom or line buffer srams or addressing issues.
what I usually do is remove all the roms and read them on my programmer then do a romident to check if the data in the roms are correct,if ok I move onto the video circuitry srams and check their outputs using a scope.
you can also carefully piggyback them on a suspect ram to see if anything changes.
 
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daeds

Newbie
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7CR
sukhbir said:
Lines in the sprites May be a bad graphics sprite Rom or line buffer srams or addressing issues.
what I usually do is remove all the roms and read them on my programmer then do a romident to check if the data in the roms are correct,if ok I move onto the video circuitry srams and check their outputs using a scope.
you can also carefully piggyback them on a suspect ram to see if anything changes.
Click to expand...
Damn, I'm screwed with just my soldering iron and multimeter then, anything I can check while I wait on at least the logical probe to arrive? :)
 
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daeds

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Lurch666 said:
Like your GnG it could be poor sockets. try removing the graphics roms then put them back to see if it makes a difference.
Click to expand...
They all seem to be soldered. :( I really need to check which are the sprites and try to piggy back some legit good chips and check for my luck.
 
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