(Topic ID: 162036)

Haunted House / System 80 Blows F4 - Transistor?

By JeffA

5 years ago



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  • 4 posts
  • 2 Pinsiders participating
  • Latest reply 5 years ago by JeffA
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#1 5 years ago

OK, here's my standard disclaimer: I'm willing to try to troubleshoot electrical issues, but I'm learning as I go and haven't learned much yet. So, please be gentle.

Just got a HH that was not working. F4 solenoid fuse was blown. Replaced and blows immediately upon power up (as in instantly). System 80 pin wiki said first step was to check bridge rectifiers. 2 of 4 tested as bad. Replaced all 4 and the orange cap. Still blowing F4 immediately. Things did light up more brightly including the displays though... so, thinking that's progress. By the way, I can start get the display to show a new zero score one player game, but there are no sounds and no coils fire.

I noticed that the diode at CR7 on the power board was looking sketchy. Disintegrated when I tried to unsolder it. Have a replacement on order (found different recommendation for that and corresponding resistor on a separate thread).

Also was reading beerorkid System 80 troubleshooting which recommended starting by testing all coil resistance and make sure none test below 2. One of the 4 main playfield flippers tested at 1.8 versus 2.4 for the other 3. Pulled wires from one lug and retested and got a much higher figure (30+ as I recall). Site says " If the resistance is higher than 2 ohms [after removing the wires for one lug], the coil is good but the solenoid driver board transistor is shorted and will need to be replaced." I've ordered some transistors and will try to track down which one is associated with that flipper and do the replacement.

So, my questions are:

is the bad transistor (or even the CR7 diode) the likely cause of the blown F4 fuse? Or should I still be looking for something else.

Does the CR7 diode explain why I'm not hearing any sounds when pressing the start button?

Thanks for any advice.

#2 5 years ago

When troubleshooting something like this, it is best to disconnect all the boards and the playfield. Obviously, when you plug and unplug things, only do it with the power off.

Then, just test the transformer panel and check voltages. If the fuse still blows, then there is something wrong on the transformer panel.

If everything is good, then connect the power supply. Then the MPU. Then the displays and cab switches to the MPU. Then the driver board. The the sound board. Then the playfield switches. Then the playfield lamps and solenoids.

If something blows at some point, try to isolate it.

Also, make sure you look at the section on pinwiki for rebuilding the power supply.

#3 5 years ago

Thanks ForceFlow. Will try it out.

3 weeks later
#4 5 years ago

Ok. After much troubleshooting was able to isolate the problem. Was the blue capacitor in the cabinet bottom. I had changed the orange one already. Thanks again force flow for the tip. I disconnected everything and that helped eliminate many other possibilities.

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