(Topic ID: 232946)

Bally 6803 Power Supply Question

By baileyfidler21

5 years ago



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#1 5 years ago

Hi there.

I’m trying to work out a power supply question with my Dungeons and Dragons 6803. I’ve checked the fuses on the power supply board, all good. When I check the test points on the board, they are all good except TP2. This reads approx 5V DC, and it wants approx 190V DC. I’ve seen solutions for if it’s reading over 190, but I’m not sure if those are the same if it’s way under 190V. Otherwise everything else looks okay. Any advice would be greatly appreciated. Thanks!

#2 5 years ago

http://www.pinwiki.com/wiki/index.php?title=Bally_6803#Power_Problems
One thing suggested there is reflowing solder joints. It also mentions, "The 190VDC display voltage is derived from 170VAC input via the same circuitry as was used by the prior generation regulator/solenoid driver board. All of the same practices apply to this board including replacing the 25Kohm trim pot."

The verbiage regarding the board on the earlier era Ballys is at http://www.pinwiki.com/wiki/index.php?title=Bally/Stern#Solenoid_Driver_Board_Issues

#3 5 years ago
Quoted from YeOldPinPlayer:

http://www.pinwiki.com/wiki/index.php?title=Bally_6803#Power_Problems
One thing suggested there is reflowing solder joints. It also mentions, "The 190VDC display voltage is derived from 170VAC input via the same circuitry as was used by the prior generation regulator/solenoid driver board. All of the same practices apply to this board including replacing the 25Kohm trim pot."
The verbiage regarding the board on the earlier era Ballys is at http://www.pinwiki.com/wiki/index.php?title=Bally/Stern#Solenoid_Driver_Board_Issues

Super! I will try to reflow the solder on the back of the power board and see if I can get power to the display. I’m assuming that this is the problem since the solenoids aren’t firing either. They probably get power from the same 190VDC. Thanks!!

#4 5 years ago

I resoldered the power board yesterday afternoon, and plugged all the connections back together. I also checked connectivity throughout the board and everything looks good. To be fair, it all looked good when I pulled it out of the machine. It trying to trace back the voltage line from the offending test point, I was able to see which wire that point was supposed to be getting its power from, on the XFMR connector. When I test the other wires coming into the power board from the XFMR they all read live voltage, but the one that is supposed to power TP2 is reading dead. From this I think I have determined that the issue is not with the power board, but rather from something upstream of the board.
One thing I should have mentioned is that I had previously replaced "BATT1" on the CPU board with the standard replacement of 3 AA batteries and a diode bridge, but I hadn't mounted them anywhere in particular, so there were two wires that I had soldered in hanging all the way down the back box (the batteries previously sat on the bottom of the back box). I was replacing the batteries a few weeks ago with the game on as recommended (to save high scores), and pulling out the battery cradle one of the wires seemed to touch something (couldn't tell what) on or near the power board, and the displays went dead and the game stopped. There was also a small amount of smoke from the vicinity of the power board, so I figured I had shorted something and blew a fuse. But all the fuses I checked were okay and the power board is seemingly fine.
Now knowing that one of the connections from the XFMR is not sending voltage (looks like it might usually send 230V if I'm reading the board right), I am not sure where to go from here. I may be out of my league and it might be time to call someone who does this as a real hobby. Any insight would be appreciated anyway. Thanks for reading all.

#5 5 years ago

In the picture linked below, the wire with the arrow pointing to it is the dead wire. I am not sure if that helps anyone. Thanks again for all the help!

IMG_4205 (resized).jpgIMG_4205 (resized).jpg
#6 5 years ago

Okay so upon further testing it seems that the wire pictured above is actually still supplying the proper voltage, so I've determined that the issue is with the board after all. My current plan is to rebuild the high voltage section of the power supply board and see how that goes.

#7 5 years ago

Update:

I plugged in the board to the machine and turned it on. I ran back from the dead test point and I've I think isolated one diode in particular. As I understand diodes, they should restrict voltage one direction but not the other. The diode in question is restricting backwards current flow (0L), but it is also severely restricting current in the forwards direction as well. I've got 230VDC coming into the diode, and only about 12VDC coming out. Would this ever be correct, or have I found the problem? Thanks!

#8 5 years ago

You sir, have found your culprit. It sure sounds like it anyway.

Replace it with the same value, and observe correct polarity when reinstalling.

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