(Topic ID: 351642)

Made Stupid Mistake... Help!

By pinball-dude

5 months ago

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  • 8 posts
  • 5 Pinsiders participating
  • Latest reply 5 months ago by PinRetail
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#1 5 months ago

My Eight Ball Deluxe was working good and I pulled the playfield to work on it . After reinstalling the playfield the machine booted up and everything seemed to be working fine. Sound was good, etc. Except the switches and/or solenoids seemed to be not working correctly. I thought maybe I plugged something in wrong and started looking at plugs and made the mistake of unplugging/replugging the J3 power connector on the solenoid driver board while the machine was on. I heard a pop come from the lamp driver board, where I saw two of the chips blew, turned the machine off and it off and it wouldn't boot afterward. Lesson learned... I swapped out the lamp driver board with another one and when I turned the machine back on it was making a loud humming sound and the knocker was locked on, so I turn it off.

I swapped out the knocker transistor on the solenoid driver board and the machine booted without issue but still had a bad hum. I ran the solenoid driver test and the only solenoid that would fire was the knocker. All the other transistors tested good when I changed out the knocker transistor, Q3, so I'm a bit confused why they are not working? I also noticed the sound board is getting very hot on the upper heat sink so I unplugged the power to the sound board. After running the machine another minute or two the knocker solenoid engaged and locked on again and now I'm back where I was before. Sounds like I messed something on the solenoid driver board, but not sure what I should be focusing on to fix it. Any ideas would be appreciated... thanks in advance!

I'm hoping I'm not the first person to do this... ha!

#2 5 months ago

What machine?

#3 5 months ago

EBDLE, linked to the thread

#4 5 months ago

I worked on a machine where the user did the same. Most likely, you blew up semiconductor devices on the 5V line. I had to replace all kinds of stuff and some boards were beyond repair from a monetary standpoint.

Take a breath. Start by removing all the board connectors. Start with the power supply. Make sure all your voltages are good. Then go to solenoid driver and connect the connector with input voltages from the supply and check your 5V and then 12V. Then connect your MPU if you have 5V and 12V (and your other supply voltages). See if you get the MPU to boot. Count your flashes. Keep going forward. If you have spare boards, keep going.

As you are stepping forward, start connecting the solenoid lines to thr driver board. You know you have problems, but see if the MPU boots and keep reconnecting things.

#5 5 months ago

The MPU will boot even when the knocker locks. What chips should I be looking at on the Solenoid driver board?

#6 5 months ago

Here are the two chips I blew on the light board. Not sure if that helps narrow it down? I'm assuming I sent 12v+ down the 5v line, blowing everything between? I replaced the light board with another one, but I don't have a replacement solenoid driver board that is working, so I'm assuming the problem lies there?

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#7 5 months ago

Yep. You let the magic out of those chips and probably others on that board.

#8 5 months ago
Quoted from pinball-dude:

The MPU will boot even when the knocker locks. What chips should I be looking at on the Solenoid driver board?

Your manual will be helpful here:


PDF page 43 (schematic) shows that Knocker is connected to Q3.

I would pull the solenoid driver board and go down the line of all the transistors. All of the identical circuits should test identical, so any transistors that don't test right, you should replace. This is a good time to refresh any solder connections that might be poor or broken on an original board.

Mostly the transistor will be locking on a coil because it is bad, but it can be U3. I'd check/replace Q3. I'd measure the knocker coil for ohms. If it reads low (less than 2 ohms) it's a blown coil. Replace the coil if blown, replace Q3 if blown. Then plug in and turn the machine on for a fraction of a second. If the knocker coil engages again, I'd replace U3.

Don't sweat this too much. All pinball techs have had these moments. It's fixable.

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