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Darksoft

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THIS IS A REPRODUCTION PROJECT MADE BY @caius ALL INFORMATION HAS BEEN POSTED WITH HIS PERMISION. CREDIT AND MERIT GOES TO HIM.

Got in a trade this untested Teenage Mutant Hero Turtles PCB:

DSCN3444.jpg


At first test the board turned out to be faulty.Sprites were scrambled and some sound samples scratchy:

DSCN1353.jpg



I launched a MASK ROM test which reported as bad all four 4Mbit devices storing sprites data:

DSCN1351.jpg


Obviously the result didn’t mean the MASK ROMs were all bad, this was quite unlikely but for fure there was a problem in the sprites generation circuit.
Most of the circuit is condensed in two ASICs, the ‘051960’ which generates the address for the MASK ROMs and the ‘051937’ which reads their data:

DSCN3359.jpg


Judging from type of fault, the ‘051960’ was generating wrong address, you can see its implementations in this snippet of schematics :

051960.jpg


Also scope analyzing confirmed my suspicions :

bad_address.jpg


This lead me to remove and replace the ASIC:

051960_removed.jpg


This restored sprites so the IC was really bad (it’s not the first time, see my past repair log of Block Hole)

sprites_fixed.jpg


Now the sound issue.A quick visual inspection relevealed that one of the two components marked ‘007340’ was cracked in two:

RSCN2153.jpg


As schematics suggest the ‘007340’ is a resistor ladder (R2R) used to convert into analog the digital bits outputted from the ‘007232’ PCM controller:

Konami_007340.jpg


Schematics show internal layout and resistors values so I made a very rough replacement that worked fine:

DSCN2508.jpg


Later I properly reproduced it :

007340_repro_installation.jpg


Another PCB fixed and another (little) custom reproduced.

 
scratchy sound is a very common issue on these, and a problem that no one seems to have found a good solution for. I wonder if a lot of people have internally cracked resistor ladders that they simply haven't realized.

I also find it interesting how common those ladders are on PCBs I find but no one seems to make replacements.
 
scratchy sound is a very common issue on these, and a problem that no one seems to have found a good solution for. I wonder if a lot of people have internally cracked resistor ladders that they simply haven't realized.
If music is scratchy then this has noting to do with these resistors ladders since the they are for the "007232' PCM controller.If sound samples are affected, most likely they are involved
I also find it interesting how common those ladders are on PCBs I find but no one seems to make replacements.
Me! :)
 
If music is scratchy then this has noting to do with these resistors ladders since the they are for the "007232' PCM controller.If sound samples are affected, most likely they are involved
@ekorz was it you who was telling me his TMNT had scratchy sound?
 
I was referring to major electronics manufacturer, but it's nice that someone like yourself does provide an option.
They are custom resistor ladder with precise resistor values.Each circuit has particular needs, R2R all not all the same :)
 
@ekorz was it you who was telling me his TMNT had scratchy sound?
Yep, my TMNT2 conversion has scratches/pops on all of the audio samples. So the opening themesong, the turtle's speech samples, etc. @cpsystem3 thinks it's the audio custom (054539) but we haven't gotten to replacing it yet. Got my donor board though! I could see if any resistor ladders are in line but he had the same symptom on a Vendetta board and solved it with the custom swap.

http://www.jammarcade.net/vendetta-bad-audio-samples/


@caius excellent log btw! I love this stuff!
 
Yep, my TMNT2 conversion has scratches/pops on all of the audio samples. So the opening themesong, the turtle's speech samples, etc. @cpsystem3 thinks it's the audio custom (054539) but we haven't gotten to replacing it yet. Got my donor board though! I could see if any resistor ladders are in line but he had the same symptom on a Vendetta board and solved it with the custom swap.
TMNT2 has different sound hardware, there is no '007232' PCM controller hence no resistor ladders.TMNT2 has the '053260' PCM chip which is quite unreliable, see this repair log from mine besides the Vendetta one:

http://www.jammarcade.net/sunset-riders-repair-log-6/

So, I really think scratchy sound is due to it.
@caius excellent log btw! I love this stuff!
Thanks.
 
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