Bally Skateball (Bally, 1980) New to pins and trying to fix.

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keithwoody

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I just purchased my first pinball machine since 1992. It is a Bally Skate Ball. When powered up the playfield lights up and it makes a buzzing noise. The green light on the board is very dim. Any help is greatly appreciated.
 
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Forgot to mention I have check all fuses with a volt meter and they are all good.
 
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Can you identify the location of the buzzing noise. Sounds to me like a bad power supply or transformer. The fact you get playfield lights makes me think Power supply is bad. Let me do some research and see if I can tell you what the voltage should be and where to check.
 
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All of the humming is coming from the speaker. You can disconnect the speaker and the noise stops. have cleaned and checked the connections. just dont know where to check for voltage and what voltage to check for.
thanks for the quick response.
 
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How comfortable are you with a meter. I have found some voltages for you. Can you locate the test points on the MPU board and rectifier board. They will be labled as TP1, TP2 etc. If so, here are the voltages. If needed we can arange some time this weekend for a phone call.

Test Points.​
Rectifier Power Supply Board:​
TP1 = +5.4 vdc (AS2518-18 version), +6.5 vdc (AS2518-49 & -54 versions)
feature lamps.
TP2 = +230 vdc (score displays) with connector J3 attached, 150 vdc with J3
disconnected.
TP3 = +13 to 16.5 vdc with connector J3 disconnect, +12 to 14 vdc with J3
connected. This voltage will become the +5 regulated voltage.
TP4 = 5.7 to 7.3 volts AC (general illumination)
TP5 = +43 vdc (solenoid voltage)
GND = Ground​
MPU board:​
TP1 = +4.9 to 5.2 vdc
TP2 = +12 to 14 vdc
TP3 = +21.5 vdc (comes from +43 vdc solenoid voltage). NOTE: If a -133
MPU board (with a 1N4148 diode at R113, as used on Granny and the Gators,
Baby Pacman, & Grand Slam), TP3 will read about 5 volts DC.
TP4 = Ground​
TP5 = +4.9 to 5.2 vdc
 
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you are an amazing sport, spalmer. not talking about keithwoody in particular- just all the owners who blow through the site, get the necessary help to fix their issue, then disappear.

all for the love of the job, i guess. :)
 
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Ike Savage said:
you are an amazing sport, spalmer. not talking about keithwoody in particular- just all the owners who blow through the site, get the necessary help to fix their issue, then disappear.

all for the love of the job, i guess. :)
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Thanks Ike. Lord knows I have been in there shoes in the past. It is all about people helping people. There is not enough of that in the world. If we all could put our differences asid and help each other, the world would be a much better place!! :cheers:
 
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Thanks for the help. Havent been able to spend much time working on my machine. Been sitting with my elderly grandmother. Hoping to get some time to work on (escape) for a bit tomorrow.
 
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Again I apologize. Don't mean to come off as a dead beat. I went on down to check out the power points. everything seems to be coming back ok except for tp5 on the mpu board. Using a cheap analog tester so its hard to read but very little voltage even for 4.9. Will get my digital out tomorrow to get some more specific readings.
 
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Not a problem. Nobody thinks you are a dead beat. My best wishes to your Grandmother!!
 
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Thank you. Any idea where to begin looking for lack of voltage for tp5 on the mbu? i have been checking out connectors and cleaning contacts this morning. made one repair to the connector and did a lot of cleaning and inspecting. the only thing i can think of is to do a continuity check on the circuit, but i don't know where the other end goes lol
 
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keithwoody said:
Thank you. Any idea where to begin looking for lack of voltage for tp5 on the mbu? i have been checking out connectors and cleaning contacts this morning. made one repair to the connector and did a lot of cleaning and inspecting. the only thing i can think of is to do a continuity check on the circuit, but i don't know where the other end goes lol
Click to expand...


Sounds like a possible ground problem. Locate capacitor c23 on the solenoid driver board. jumper the negative side of this capacitor to any ground in the backbox and try to power it up. If the machine boots up, you have a problem with the white/brown wire that runs for j3 pin 10 on the driver board to j3 on the rectifier board. If not we will keep hunting.
 
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What are you getting on TP5 with your digital meter. Are you getting the 5 volts on the voltage regulator board at tp1 and tp3?
 
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noticed when i checked the fuse on the solenoid driver board that the noise went from a steady buzz to a almost thumping noise from the speaker. did a continuity check on the white and brown wire and its strong.
 
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It seems that ou are mssing your 5 volt. I think it is trying to boot but can not without the 5 volt. Did you get 5 volts at the voltage regulator on tp1 and tp3?
 
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Yeah its bizarre all the voltages on the rectifier checked out. neither tp1 and tp3 on the solenoid driver are showing anything. the only place showing 5 volts is on the lamp driver and the orange wire coming out of the rectifier
 
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Diconnect connector j4 at the MPU board. Also disconnect all of the connectors going to the lamp driver board (board directly below the MPU board). Retest for voltage at tp1 on the solenoid driver. If it is good, reconnect the MPU board and retest followed by the lamp driver board. It could be one of these baord pulling to much current or could be a bad voltage regulator on the solenoid driver board (Q20).
 
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Ok with all of those disconnected my voltage on tp1 of the solenoid driver is now 1.4 volts
 
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Check TP5 on the solenoid driver board. If it is between 13 and 16 volts, replace voltage regulator Q20 on the solenoid driver board. This is a common failure. It is the round voltage regulator in the middle of the large black heatsink on the right. It can be found here..... http://www.marcospecialties.com/pinball-parts/LM323K.

If you have an electronic part store near you, you may be able to find it locally. Any of these part numbers will work. All the same just different manufacturer.

NTE 931, LAS1405 , 78H05KC

Troubleshooting long distance, I can not garantee this is it, but it seems the most logical problem given you have proper voltage everywhere else. Q20 supplies the 5 volt for the rest of the machine. Make sure to reapply a little heat sink compound to help disipate heat.

another option is to replace the board with this new universal board. http://www.marcospecialties.com/pinball-parts/ULTSDB. Not sure what your budget is.
 
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ok i apologize ahead oh my post. I dont know what was going on last night. Bought a new better quality (no excuse) digital meter today. tp4 on the rectifier board is showing up as nothing. all the other points are within limits. once again i apologize i have no idea what was going on there.
 
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O.K. Now I'm confused. PM me a phone # and best times to give you a call. Might be a few days before I get some free time.
 
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Pulled the transformer unit to check it out. Turns out one side of bridge rectifier 2 is dead!
 
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