(Topic ID: 264452)

Help identifying high voltage mod to Bally solenoid board (SDB)

By slghokie

4 years ago

Topic Stats

  • 9 posts
  • 4 Pinsiders participating
  • Latest reply 3 years ago by slghokie
  • Topic is favorited by 1 Pinsider


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#1 4 years ago

Looking to see if anyone know what this mod is to the high voltage section on my bally SDB. Came this way in my Flash Gordon and worked....up until I tried to do the ground mods. Apparently it did not like those. Looks like I fried the parts for high voltage so I dont have power to displays. But seems like the solenoids still work.

First I replaced the caps and did the 5v mod and it still worked. Then I did the 2 ground mods for the caps and it blows F2

Need to replace the parts and can try and read it off most...but was looking to see if any documentation existed on this mod. Seems it is based around 615 BU806 trani. Was hoping for a parts list to double check my read of what is on the board.

Any help would be appreciated.

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#2 4 years ago

I've never seen that mod before. It appears the hv is non-adjustable with that mod though.

#3 4 years ago

It would be interesting to draw out that circuit. I don't see how it is being regulated though.
The BU806 seems to be a simple Darlington transistor.
What voltage did it produce when it worked?
Chris Hibler - CARGPB #31
http://www.PinWiki.com - The Place to go for Pinball Repair Info

#4 4 years ago

There's two zener diodes in series down the bottom that are setting the output voltage. That poor transistor without a heatsink is probably dissipating around 10 - 13 watts. Ouch..

I might have missed something but this is what I've come up with from the pictures (in the pink box): Basic zener regulation with a power (darlington) transistor.


#5 4 years ago

Bear with me I am not an EE, but here is what I read on the part labels in this circuit:

400 V 1µF cap
10 X10 +/- 5% resistor at R52 = 100 ohm 5%
8806J RN60C (Dale) possibly a resistor?
NTE 505 diode at C28
5A 504 diode at C27
SEC 615 BU806 at RT1
10 X10 +/1 10% at R35 = 100 ohm 10%

Not entirely sure about the resistor values.

Thanks to my mod attempt...they all have continuity through them, and the F2 blows. Guess I need to find replacements...unless this is not a good solution for high voltage. Any thoughts?

Guess I need to test the bridge as well.

#6 4 years ago

No heatsink on that BU806 transistor is bad.

Just get a HV rebuild kit and do it properly. You're going to have to find a heatsink (as close as you can) for the original 2N3584 transistor at Q21.

#7 4 years ago

slghokie , like Quench says, return it to the factory configuration.
It's an interesting hack...but it needs to be retired.
Chris Hibler - CARGPB #31
http://www.PinWiki.com - The Place to go for Pinball Repair Info

#8 4 years ago

Oh BTW, I mentioned in another thread yesterday that the below heatsinks are what I use on the 2N3440 transistor at Q23 when boards come my way with it missing.

You can probably find similar locally.
ebay.com link: itm


4 months later
#9 3 years ago

Finally got back to this. Like ChrisHibler and Quench said I put my Flash Gordon SDB HV back to original and am back up and running. Those heatsinks look boss Quench!

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