(Topic ID: 244053)

Evel Knievel: Bally rectifier board, bad TP3

By Brewchap

6 months ago

Topic Stats

  • 43 posts
  • 5 Pinsiders participating
  • Latest reply 5 months ago by Quench
  • Topic is favorited by 4 Pinsiders


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#1 6 months ago

I am working on a new to me Evel Knievel that I was able to power up and run a coil test with no problem. However I have ran in to a problem getting the MPU to boot. I believe that I traced down the problem to the rectifier board, test point 3, which only has 6 DC volts and needs to be 11.5 DC volts. All other voltages are correct. If I am correct, then this is my 5 volt input, and without this, the MPU will not boot.

Would anyone care to confirm if I am thinking in the right direction?

#3 6 months ago

Thanks Quench. The diode test showed an open circuit. I got some on order.

#4 6 months ago

I replaced all 3 bridge rectifier and nothing changed. I thought for sure that this would fix the problem.
Still have 6 DC volts on TP3.

#6 6 months ago

Going by the picture

1. No reading
2. 0.475
3. 0.475
4. No reading

651px-TestingABridgeRectifierFourSteps (resized).jpg
#11 6 months ago

I found the picture on Pinwiki web site. Credit goes to Chris Hibler.

I measured and tested my last bridge rectifier. It tested good like it should. I installed it and powered it up. The MPU still will not boot. So I tested the BR2 again and it's bad again. Something must be shorting it out. It reads the same as in post #6

#13 6 months ago

Installed another MPU and the pin booted up. Thanks for the help and info!

2 weeks later
#14 5 months ago

I just replaced Fuse F4 after I found it blown, and it blow again telling me that BR2 is bad again. Is there anything that I should look for that would continue to mess with BR2 casing it to go bad? This pin has been running 24/7 for the last two weeks. Now, right before I found the fuse blown, I did find that the power cord going to the on/off switch in the cabinet, had broken its solder connection removing power from the pin. I soldered that back on and found the fuse blown.

#16 5 months ago

No I'm not measuring any short across the BR2 pins like I thought that I would. I checked TP5 and didn't find a dead short, but I did measure some resistance.
I also checked the coin door and made sure that the green wire was not touching. What ever is causing the problem makes a loud hum in the speaker before the fuse blows.

#17 5 months ago

I did measure a dead short on BR3.

#19 5 months ago

From memory, 200volt 10amp. Its possible that I'm over heating them. I did have a hard time getting the solder to flow around the pins. I got a hotter iron that I use on the playfield that I can try. Flow the solder faster might be the trick.

#21 5 months ago

Good idea. I'll do that also.

#22 5 months ago

Well, I replaced BR3 (also replaced knocker and chime coils that were bad) and now all of my solenoids are locking on when I turn the pin on. What is going on now?

#23 5 months ago

I went ahead and disconnected the newly install coils, but that didn't help.

#25 5 months ago

I found it.....I had some transistors backwards.

#26 5 months ago

I thought that I fixed this, but it is happening again.

Quoted from Quench:

Does it happen if you disconnect J4 from the SDB (Solenoid Driver Board)?

All solenoids lock on

#27 5 months ago

I have to pull J1 and J5 from the SDB to keep the solenoids from locking on.

#28 5 months ago

No it's working again. I don't understand this. On top of this, the new coils for the chime and knocker are not working.

#29 5 months ago

Q3 and Q7 I think is for the chime and knocker

#30 5 months ago

I keep shorting out Q3 and Q7 for some reason.

#31 5 months ago
20190701_163906 (resized).jpg20190701_165333 (resized).jpg
#34 5 months ago
Quoted from Quench:

With these two connectors removed:
* What voltage are you measuring at TP3 on the SDB?
* what voltage are you measuring at pin 24 of the U2 chip on the SDB
* Is the flipper enable relay clicking on at powerup? i.e. do the flippers always flip when you press the flipper buttons regardless of being in game over mode?

TP3 is 5.25 Dc volts

Pin 24 is 5.23 Dc volts. When I first touched pin 24, all of the solenoids fired at one time. Of course I jumped and lost connection. The second time I was able to get a reading from the DMM

No the flippers do not work in game over mode.

#36 5 months ago

Could that cause failure of the Q3 and Q7 transistors? I believe that is for the knocker and chime since they dont work. It seems like they fail as soon as I turn the power on.

#38 5 months ago

At first activation upon boot up at this point. I changed to another SDB that fixed the Q3 failing, but the Q7 (chime) is still popping the transistor. Also so far no coils locking on at power up with this board.

#39 5 months ago

Is this wired right? I'll clean up the solder job in a bit.

20190701_163906 (resized).jpg
#41 5 months ago

Ok I found that I had .3 ohms on the coil. I replaced the diode and measured again and had 53 ohms. I then replaced Q7 on the SDB board. At power up, the Q7 blew.

#42 5 months ago

I replaced the diode again and now it's working!

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