(Topic ID: 250796)

Harlem Globetrotters help please

By Don44

49 days ago

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  • Latest reply 5 days ago by treborlicec
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#2 49 days ago

It seems all 3 coils lead to U3, a 3081 transistor array chip on the solenoid driver board (the upper right board in the backbox). Get a good look at the transistors and the U3 chip on that board.

#4 49 days ago

Doesn't look like it's used in that game, according to the schematic. Looks the the transistors that drive the 3 coils are Q10, Q11, and Q12. I would check those 3 transistors, check U3, and check each of those coils under the playfield and make sure they're wired properly with respect to their diodes. Also check the resistance on the coils (anything generally 2ohms or less is bad).

#8 49 days ago

R50 looks like it's part of the +5v circuit produced on that board.

Considering this is your first SS Bally, it's probably smart to read up on the pinwiki guide and familiarize yourself with some of the common problems, fixes, and upgrades. You will likely need to replace a number of connectors, for starters.

Does the mpu board have any battery corrosion? Are the boards all original or have any been replaced with aftermarket ones?

I would also recommend checking all the voltages at the rectifier board and solenoid driver board. There are test points on both boards you can hook your meter up to. It's really important to verify proper voltages before troubleshooting, bad/missing voltages can create all kinds of weird problems. If you need help setting up and using the meter, just ask! It's a *very* helpful tool, it's worth learning the basics on yours.

#10 48 days ago

Looks like R50 is a 2.2 ohm resistor. You can set your meter to check resistance (often an 'omega' symbol on the meter).

To check DC voltage, set your meter for DC volts--the symbol is often 2 parallel horizontal lines, one dotted and one solid. Next place the black meter lead on ground. You can tuck the lead under the ground braid in the backbox if it's easier, though you'll also see a test point for ground on the solenoid driver board as well. Either should be ok for the test, afaik.

Here's what you'll look for on the solenoid driver board:

TP1 = +4.9 to 5.2 vdc
TP2 = +190 vdc (but often turned down to 170 volts to increase score display life).
TP3 = +4.9 to 5.2 vdc
TP4 = +230 vdc
TP5 = +12 vdc to 16.5 vdc

So, black lead on ground...now with the game on, carefully touch the red probe to each of the test points on the solenoid driver board and jot down the voltages you get.

Also, you'll want to confirm proper voltages on the rectifier board. Test points and voltages are as follows:

TP1 = +5.4 vdc
TP2 = +230 vdc
TP3 = +12-14 VDC
TP4 = 5.7 to 7.3 volts AC (general illumination---don't bother checking this one for now---)
TP5 = +43 vdc (solenoid voltage)
GND = Ground

#12 48 days ago

You're welcome! Hopefully other techs will feel inclined to jump in at any point too.

Careful--that's a 2.2 ohm, not a 2.2k (2200!) ohm resistor. I would suggest only using an exact replacement.

I'd go ahead and do the voltage checks for now. Chances are you will eventually need to do at least some connector re-pinning, and I'd also recommend changing the big caps on the solenoid driver board along the way.

#15 48 days ago

Definitely sounds like issues with the solenoid driver board as well. In addition to that, you're going to need to re-pin a number of connectors, including any that may have been reached by the battery leakage. Still, sounds like a good candidate for the effort! Not sure how experienced you are with board work, but you can probably get away with fixing the solenoid driver board at very least.

I'll defer to Quench at this point because he knows this stuff inside and out and we're approaching the limits of my knowledge ...but what I see so far is that your 5v on the sdb is definitely too high, possibly due to the burnt resistor? Could be more to it than just that though...

1 week later
#25 41 days ago

Correct, just note it's the regulator on the larger heat sink on the right side of the board. I only mention this because there's another smaller heat sink for the voltage regulator for the high voltage displays on the left side. Don't want to mix those up!

#28 40 days ago

Any plans for the old boards?

I'd recommend lots of re-pinning, but Quench should be able to steer you exactly where to focus.

#33 39 days ago

Here's the kind you'll want, 0.1" pins (link is for a bag of 100):


As Quench also mentioned, you'll want to reuse some of the old housings especially if replacements aren't available. A small jeweler's screwdriver can be used to push the locking tab of the old pin so you can pull the pin out of the housing.

I'd love to take a shot at refurbishing the old boards if you're interested in getting rid of them. Maybe we could figure something out if you're interested...

1 week later
#35 31 days ago

Check how many points each switch scores, chances are whichever switch scores 300 points is gapped too closely. I think a spinner may be the culprit, but take a closer look and see what you find.

#37 29 days ago

Sounds like you might have a couple of bad SCRs on the lamp board. Sometimes they'll cause a lamp to lock on when they go bad. Here's some info i grabbed from Clay's repair guides:

Lamp Always On.
With the game on and in score display test mode, connect one end of an alligator jumper to Lamp Driver board TP2 (ground).
Connect the other end of the alligator jumper to the GATE (G) of the SCR in question. On the larger MCR106, this is the left leg. On the smaller 2N5060, this is the right side (center) leg.
The lamp in question should turn off.
If the lamp does not light, the SCR is probably bad. Test the SCR with the power off using a DMM in diode test, as described below. If the SCR tests bad, replace it. Repeat steps above 1 to 3.
MCR106 and a -14 lamp driver board: now ground the input leg of the CD4050 connecting to the SCR in question. If the lamp does not go out, the buffer chip is bad. Repeat steps above 1 to 3.
If the lamp still won't go out, replace the U chip connecting to the SCR in question. Repeat steps above 1 to 3.
Testing the Lamp Driver SCRs POWER OFF.
You can also check the lamp driver board's SCR's using your DMM, set to the diode setting.

Check the manual's schematics to figure out which SCR controls the lamp(s) in question. This information is on the Lamp Driver schematic page. Write down the SCR's "Q" number.
Look at the connectors at the right of the schematic. There the lamp name/descriptions will be listed.
Follow this line back to the first "Q" (SCR) that intersects this line. Note the SCR number (for example, "Q8"). If the schematic lists a "**" next to the transistor, this means it's a MCR106-1. Otherwise it's a 2N5060. Also note the chip that drives this SCR ("U1"). Both these components could be damaged (but generally it's just the SCR).
You can remove the lamp driver board, or leave it installed in the game. Use your DMM set to the "diode" setting.
MCR106-1 Lamp Driver SCR test:

Put the black lead of your meter on the outside "cathode" leg (labeled "C") of the SCR.
Put the red lead of your meter on the outside "gate" leg (labeled "G") of the SCR. Your meter should read .4 to .6 volts.
Swap the meter leads. Now the meter should read 1.4 to 1.6 volts.
If your meter reads anything outside the values above, replace that MCR106-1.

#39 29 days ago

Which transistors are you talking about? Are you referring to the diodes on the switches perhaps? Post a couple pics if possible. It's very likely you're going to need to do some more re-pinning on the mpu if the lights are coming on at the wrong times. There's a lot of corrosion on the old mpu, and that corrosion can damage the female connector pins too.

#41 29 days ago

Green? Are they capacitors by any chance? They're disk shaped. If that's what you're referring to, you'll notice a number of switches under the playfield have them. For reliability and to prevent weird switch problems, i always replace each one.

#43 28 days ago

They allow the switches to detect quick hits/activations. They can be removed (usually one leg will get snipped) to see if it fixes any switch issues. Due to their age, most of the time they're bad or going bad soon. The ones you want to replace them with are here:


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