Arcade Collecting > Pinball

Request: Help with Bally Harlem Globetrotters (Resolved)

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TopJimmyCooks:
I am new to the pinball end of this.  Just got the machine locally.  It played fine and everything worked except a lot of lights were out. The entire left side's lights were out, but I didn't worry about it too much because at least one fuse was visibly blown.  

To get it to it's final location I had to take the backbox off.  I labeled all the connectors and took them off.  Plugged everything back up including the ground strap.  Game played as before, as expected.

After about 10 games, later that day, everything started running slow.  As in:

*  turn machine on, hear the starting song playing very slowly.  MPU flashes 7 times, no delay there.
*  after about 30 seconds you can hit start and it will feed a ball
*  the flippers and the playfield solenoids work as normal.  However, points scored take a long time to display and chime.  
*  when you drain it can take about a minute to feed the ball back.
So basically the EM parts work fine, but the solid state stuff, displays, chimes, etc. are off kilter.  The onboard diagnostics are not helpful so far, since I have seven good LED flashes which gets me past most of the problems they cover.  I found one reference to a clock chip on the web but it seems the slowdown is not a common problem at least in terms of coverage on the internet.  Any suggestions of stuff to try or should I just send the MPU off for repair?  Try buying a clock chip?

I am going to proceed with testing and replacing fuses and cleaning (gently) the mpu connectors.  I appreciate your help.  I have basic electronics knowledge and can solder/desolder/use a meter.  Thanks

TopJimmyCooks:
Thank you - will try looking at that area and report back.  Time to practice up on my board soldering.   

I DL'd the Clay guide but in the unauthorized version I got, the hyperlinks are all broken so I have to track each little sub document down by hand.  also, I only grabbed the Bally 77-85 sections.  anything in the other sections I should get that relate to my machine?

TopJimmyCooks:
PBJ -
One thing I did note is that Clay said to replace the on board battery.  I looked and there is a very small amount of corrosion/darkening on traces and diode leads below the battery.  also evidence of past cleanup.  certainly no major damage. 

is the C16 a component that can be hit by battery corrosion?  the various labels and notes marked on the board seem to indicate the battery was replaced in 1996.  This is when the machine was sold to the home use owner I got it from.  Should I go ahead and do the 3 AA battery thing while I've got the board out anyway, or just keep an eye on things if it's working?

Again, thanks for your knowledge and help. 

TopJimmyCooks:
Ok, went to radio shack and got the capacitor.  Practiced on a junk mouse pcb for a few minutes and then had no problem desoldering and resoldering C16.  I got excited because the old one practically fell off as soon as I touched it.  I resoldered the R23 right next to it, since I desoldered one of it's legs by mistake.  This is an easy board to solder on, traces are way further apart than newer boards, and the pads/holes are large. 

First game, played slow as before and stopped when the 2nd ball drained, it never fed back to the plunger.  turned on and off a few times, get the seven flashes, single start up tone on the 5th flash, but game will not start on start button.  Credits/match display reads "200004" and bottom left reads "0000" the rest are blank.  Should I try changing more components on traces coming out of the 555, or just pay the $85 to have this repaired?

Thanks for your help. 

TopJimmyCooks:
pic of the mpu after my work:

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