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CPS3 - P2 "up" is stuck on

mathewbeall

mathewbeall

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Hi Folks!

I was getting ready to sell a CPS3 mobo - and realized that P2 UP is stuck high. After doing some reading, I will be testing CR2 (p2 up is pin 18 on the solder side) to see what it looks like, but it seems like its either CR2 - or the custom that it goes to? Anyone else had this type of issue (an input stuck high) and managed to resolve it?

Matt
 
I pulled CR1 and CR2 - thinking I would maybe swap them - but tested with both of them out before I did that.

with both of them out - I *still* have P2 UP stuck high - does that mean its an issue with the custom 2929 chip, and I am kind of screwed?
 
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Can you test in different cabs / superguns? I had a similar issue a few years ago where a board would work in a cab just fine, then tried it on a supergun and one of the directions on 2P would be stuck high, tried on the cab again and it would be fine.
 
Then its the custom thats stuck.

Schematic for CR084 in case anyone needs it

1626034846303.png


CR2 - Pin 8 is 2P UP input - and its output is Pin 9 going to the Custom 2929 chip

Just curious can you measure the resistance between Pins 1 & 8, 1 & 8, 8 & 9, curious to see what you get, should be close to the above.
 
CR2

between 1 and 8 - 1,400 ohms
between 1 and 9 - 1,670 ohms
between 8 and 9 - 283 ohms

CR1

between 1 and 8 - 1,000 ohms
between 1 and 9 - 1,220 ohms
between 8 and 9 - 220 ohms


Although right now - I don't have CR1 or CR2 installed - and P2 UP is still "high", but no other p2 inputs are stuck high. Leads me to believe the custom is bad.

Matt
 
Yup, since it's still stuck high, definitely the 2929.

I wanted you to compare the resistances to see if they are different and they are, even if slightly, seems to indicate enough overvoltage/current long enough to start breaking down those resistors a bit and as well as cause damage to the 2929 custom as well.

Cave CV100 pcbs also suffer from this type of damage IIRC, I think some of the pins are directly connected or with a resistor from the jamma edge to the sh2, etc, and if you short, overvoltage/current some of these you can end up easily damaging the sh2.
 
xodaraP said:
Could you try testing for continuity between the pin that is stuck and +5?

Also might be an idea to try to connect that pin directly to GND to see if it can be forced low. If it can’t, definitely a bad input on the custom.
Click to expand...
I got the system all hooked back up.

When its on - all the buttons off the jamma edge are +5v.

When I ground the P1 buttons out, I see the corresponding button press in the input menu.

I hooked CR2 back up - and even grounding out the P2-UP ( 18 ) pin doesn't change the state.

So that means the DL2929 is bad right? I am assuming there isn't a stockpile of DL2929 chips out there somewhere? I am thinking this is pretty much just a dead system at this point.

Matt
 
I don't think I have the skills to solder it back on though - so would need to find someone that could do that. In addition to being not sure if the chip could make the chip. I appreciate the offer - but it might not be worth it. I would also need some new resistor strips - not sure if those are made either anymore.
 
yup. I've got a CPS3 mobo with P2 button 5 stuck on... went through the same troubleshooting stuff you did and determined the problem is the custom itself.

best case is to find a junk CPS3 mobo for cheap and hope that the custom is good.
 
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