Request: Help with Bally Harlem Globetrotters (Resolved)

[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:

[TopJimmyCooks]

I did not hit the switch on the mpu, I'll try that. 

I think I am going to send the thing out for professional repair.  I am looking forward to going through and servicing everything, slingshots, flippers, etc. and as a pinball beginner I would like to start with a known good computer as a baseline.  On all the em stuff, there are multiples (3 pop bumpers, 2 slingshots, etc) so if I jack one up, I can look at a working example elsewhere.   

I really appreciate your input.  Thanks.

[TopJimmyCooks]

bit the bullet and bought an alltek mpu with the test board.  with my luck I'd blow $100 on board work and have some other part on the thing crap out 6 months from now. 

[pbgarage]

  Whole bunch of corrosion on that IC in the photo....

Needs to have a strip socket installed and a new chip. That
may be the problem.
You DO need to repair/neutralize all corrosion before all else.

 Only time I've encountered  "slowdown" in a pin, it was a bad game ROM(s).

Fred
TX
CARGPB#8
--------------------------

pic of the mpu after my work:

[TopJimmyCooks]

  Whole bunch of corrosion on that IC in the photo....

Do you mean the 8 pin timer chip? (between R22 and R23) or the larger IC in the top of the picture?  I have ordered parts to replace all the components in that area.  The corrosion looks like it was worked on in 1996 or before according to the notes on the board, and the battery had been replaced with a capacitor.   Everything worked before I moved the machine.  I got a replacement board and have set this aside for now, but I do want to get it working if possible.  it looks nothing like the boards posted in the guides as examples of bad corrosion.  I just need to get busy and check all the traces and components, etc. 

I really appreciate the input and I'll be back for more as I get into this project. 

[pbgarage]

  The small one. Any/all corrosion is bad in spite of
anything you've read, anywhere.  Until it's all taken
care of, all bets are off on how long a board will
hold up.


Fred
TX
CARGPB#8
========================

[TopJimmyCooks]

Thanks to the help of these two fine gents and a whole lotta multimetering, I got everything working!

*Figured out the playfield controlled lights were all out due to the F1 fuse-burned out. Replaced it and they all worked.
*replaced a bunch of weak or burned out lamps.
*traced the nonworking GI lights back to the connector on the Rectifier board - jiggled the connector until it worked
*cleaned all the major crap off the playfield.

Next up:
*Drink beer.  Play pinball.
*replace connectors and header pins on rectifier board - they are baked.
*work on a few lights/sockets/scrs that are still a little flaky. 
*proper playfield cleaning and rubber replacement
*get the coin mech's working better

Long term:
*replacing some components and cleaning corrosion on the old MPU to try to get it working.  (then sell alltek board for $$$$$$$)
*flatten playfield plastics
*level the playfield inserts and maybe touch up around them. 

Good night and good luck.