DE Jurassic Park TKOed

mecha

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well, never thought I'd be posting in the pinball forum.

we were moving games around tonight and I needed the breaker where the pins were at turned on and noticed something rather peculiar on Jurassic Park that it didn't do the dino growl and play the music during what would ordinarily be the T-rex diagnostic. it made a strange click, and faintly hums and the DMD is completely blank.

am I looking at a popped fuse somewhere, or did the MPU(?) crap out?

I noticed lately while people were playing it that the background music would completely go out and it would play that power-on growl sound repeatedly probably when the ball was hitting targets/kicks.

and as I predicted, something bad was bound to happen sooner or later based on that disappearing music issue.

any advice would be nice, otherwise I know of a guy somewhat close to me that was a Data East tech or something along those lines, but if I can somehow fix this myself for experience that's even better.

thanks
 
alright.

tested +5 voltage at the test points next to C17, I came up with 3.64V.

pulled CPU board and power supply boards, despite all the hackery on the power supply board (I'm guessing it got REALLY HOT in the past) I'm seeing continuity between components. no bad solder joiints, based on just wiggling pins. by comparison, the board that controlled the lights had noticeably bad solder joints a few months back, hence why I'd lose the GIs on it... not the case here.

am I supposed to test the 12V bridge rectifier inside the back box or do I take that out? I guess if that goes bad it'll drag down all the other +5 voltage based on what I read at pinrepair.com.
 
thanks everyone for your continued support.

now what am I doing wrong at KLOV?
 
Wish I could help, some of the guru's should chime in here soon.
 
Here ya go http://www.pinrepair.com/de/index1.htm#psprob

remember +12 volts D.C. comes from the back box mounted bridge rectifier. Remember this bridge can go open or short, causing low +5 volts or a blown fuse, respectively. If good +12 volts is coming from the backbox mounted bridge rectifier, next check the 2N6057 transistor (replace with a 2N6059). If this does fail or leak, a low +5 volts will be seen. Past that there is a MC1723CP voltage regulator chip too, but this rarely fails.

If all these things check out Ok, now check the electrolytic capacitors on the power supply board. These can leak, and corrode the traces on the power supply board underneath them. This is a more common problem then it may seem!
 
ok, I just reinstalled the power supply board, and as I was getting ready to test the bridge rectifier, it booted up.

I metered the +5 test point, I'm getting 4.99-5.00V.

are we... good?
 
Guess all you can do now is make sure that all of your connectors are seated properly and wait for the problem to pop up again.
 
Reflow solder on the headers and retin the pins or replace the headers and/or molex connectors would be my next step. You most likely revived it by wiggling or re-seating cables and such.
 
probably. that's the same way it was with the GIs, except with that I thought it was loose wires instead the connector itself when it was really the pins were so bad on the board I could visibly see them move when I wiggled them from the other side. lol

I'll take it though. I like stupid solutions. :p

is the +5 voltage supposed to be that close to 5.00V though? I keep seeing test points for the +12 that say they're "unregulated", was wondering if there's a +5 adjustment at all with pinball PS boards.

mind you, prior to the game taking a shit entirely it was doing some erratic things with sound where the music would cut out and it was looping the dinosaur growl over and over until you lost a ball.

of course with me losing power somewhere along the way I guess anything's possible. the +5 was at 3.64 when it was dead.

I did also unscrew the 2 bridge rectifiers in the backbox. do those have to ground against the metal plate at all by chance?
 
of course with me losing power somewhere along the way I guess anything's possible. the +5 was at 3.64 when it was dead.

I did also unscrew the 2 bridge rectifiers in the backbox. do those have to ground against the metal plate at all by chance?

They don't have to ground against the metal plate. They have AC coming in and they output DC.
 
ah good to know. yeah, this board kinda looks like it's seen better days. there's jumpers everywhere lol.

I wouldn't buy a replacement PS board. PS boards can be completely rebuilt for way less than it would cost to buy a replacement.
 
no resetting. I don't think it ever reset. just the music would cut out. that could potentially be like a sudden drop in voltage on the 12V line and then it came back.

pinrepair did say if the bridge rectifiers are shorted/open, cutting off the 12V, that it would cause the +5 to drop.
 
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