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I've never plugged in a JAMMA harness backwards...Until now….

BuddyC

BuddyC

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I got a Data East - Dunk Dream 95 today in very nice condition, but showed some jailbars and graphics issues on first boot. Opened up the PCB, cleaned everything and reseated the eproms.

These Data East PCBs are two stack and both sides are component sides, solder side on the inside.

Since I am a idiot, I plug it into my NNC and flip the power without double checking everything.. Like I usually do… Tube shows no signal . I'm like, hmm…. Thats weird…

Then I notice the the nasty smell of burning electronics.
Fuck.
I quickly turn it off and am puzzled. Did I blow a cap or old part? Is something shorting?

Nope, I am a idiot and plugged my jamma harness backwards. Fuck again..
The board Looks okay so I hook it up again and cross my fingers...
IT BOOTS!

Sound and graphics all good. All directions, start, button 1 and 3 all good. Button 2 not responding.
Fuckarooni!

9D69B8F1-1D8D-4D66-9E35-A7445F53123A.jpeg


Board looks okay, so I started tracking from jamma pin 23 (1 player button 2) and looks like I royally fucked up IC4
Fuck, fuck, fuck…
A0263505-A18A-4306-B4B3-068E260299DF.jpeg


Does anybody know where I can get a replacement part that works with this?
Any tips would be greatly appreciated!

Part ID for IC4
C581EAB1-95E4-41DD-86B3-5D47DE5BC914.jpeg
 
plugging in a JAMMA harness backwards almost always blows out the button inputs because the -5V lines up with button 3 and 12V lines up with button 2

But yes as Ekorz say always run a key in your JAMMA connector. and if your JAMMA board doesn't have the notch I recommend CUTTING one. Normally I don't advocate taking a dremel to a PCB but the VAST majority of PCBs missing the notch are bootlegs and I'd rather cut a notch in those then risk blowing out a PCB I actually give a shit about.

As for fixing this. Those look like custom resistor packs, which means you're likely going to have to source replacements from another Data East PCB. in the mean time though maybe swap one out with a resistor network from the Expansion IO that you might never need to use.
 
twistedsymphony said:
plugging in a JAMMA harness backwards almost always blows out the button inputs because the -5V lines up with button 3 and 12V lines up with button 2

But yes as Ekorz say always run a key in your JAMMA connector. and if your JAMMA board doesn't have the notch I recommend CUTTING one. Normally I don't advocate taking a dremel to a PCB but the VAST majority of PCBs missing the notch are bootlegs and I'd rather cut a notch in those then risk blowing out a PCB I actually give a shit about.

As for fixing this. Those look like custom resistor packs, which means you're likely going to have to source replacements from another Data East PCB. in the mean time though maybe swap one out with a resistor network from the Expansion IO that you might never need to use.
Click to expand...

PCB has the notch, but it was my own fault for being a idiot. Rest assured. Key pin has been installed!
I’ll give the resistor network from the expansion IO a go tomorrow.
Thanks for the tip!
 
Looks like IC 7 and IC8 are good candidates. Will give it a go tomorrow.
C32C5A56-DA97-4022-84FE-7D0ED5668202.jpeg
 
it's resistors and capacitors,
if i had to replace one i think i'd just tack 0603 smd parts to the pads on the board

like the above post :)
 
Has anyone ever considered producing a small PCB that would protect the game board by detecting orientation and not sending power if incorrect?
I know I know, a complex solution for a very simple issue (just don't do it) thing is, most of us have done it... At least once.

I'm not a fan of keys, some of my "ghetto" PCBs don't even have a key slot.
Still to this day I refuse to install a key into my JAMMA harnesses for that reason.
 
its a rite of passage brother, bet you won't do it again, cause you will always double/triple check from now on ;) , I have done it myself :D

For the board, do what Twisted suggested swap out one of those packs and see if its all good and let us know how it goes.
 
Good news!
As the awesome @twistedsymphony suggested, I replaced both IC2 and IC4 from the resistor network on the Expansion IO side (IC7 and IC8 )and everything is working again!

Plays, sounds and looks beautiful!
Thanks to all for the help!

D7F61CDD-F26A-4C36-829E-937C562C4800.jpeg
 
Last edited:
Nice, good friend did rebuild mine but swapping is also a good idea.
What is the "Expansion IO" exactly for?
 
The PCB supports another monitor and 3rd and 4th players, so that won't now work (although if you had taken the packs from the other end, maybe it could?). Anyway, not an issue if you're never going to run it that way.

Dunk Dream '95 / Hoops '96 has one of the best 4-player implementations I've seen, I suggest you try it out if you can.

Pinout is here:

https://www.arcade-projects.com/thr...ional-unique-second-screen.13167/#post-215851

Some pics of how it works are in the same thread three posts down.
 
Very glad you fixed it.

I affixed a voltmeter to my jamma connector on the power end, on the parts side. Line the volt meter up with the power pins and you're good to go. Just make sure it's low profile enough to fit in a cps2 A board.
 
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