(Topic ID: 291802)

Space Station voltages very high on aux driver board

By Archieball

7 months ago

Topic Stats

  • 6 posts
  • 4 Pinsiders participating
  • Latest reply 7 months ago by Archieball
  • Topic is favorited by 2 Pinsiders


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#1 7 months ago

I am trying to help a friend to get his Space Station on it's feet. I have rebuilt the auxiliary driver board, but I am getting some strange voltages. My friend has invested in a brand new cpu board, so I want to make sure that all voltages are ok before I try to boot it. I have no voltages going out of the board, just coming in.

I am not sure I am measuring in the right spots, but looking at the schematics I would think I am. Black multimeter wire on the ground strap and measurements taken from the fuse holders. The 50vdc circuit gives around 70vdc and the 25vdc is north of 40vdc. I have plugged the transformer plug according to European voltages. Here in Norway we have 230vac, so I have the jumpers set to that.

One strange thing worth mentioning is that I have access to a working Roller Games which has the high voltages in the same spots. Not as high, but close.

Any thoughts on what I am looking at here?

#2 7 months ago

40v and 70v sounds typical to me.

#3 7 months ago
Quoted from PinballManiac40:

40v and 70v sounds typical to me.

Ok, thanks! We'll give it a try then. A bit strange though that the voltages are that high.

#4 7 months ago

The voltage specified is the AC output from the transformer. If you want more information search for "RMS voltage". It is heavy reading if you're not schooled in mathematics and electronics. It's too heavy for me. I'm not well schooled in either mathematics or electronics (only finished secondary level education in those subjects). All I know is that the DC voltage is usually the AC voltage multiplied by the square root of 2.

25VAC after full wave rectification is 25 * 1.414 = 35VDC
50VAC after full wave recitifcation is 50 * 1.414 = 70VDC

The AC voltage is nominal. It will depend on your actual line voltage and the transformer winding that you select. Measure the AC input and do the arithmetic. It should closely match.

#5 7 months ago

The voltage rails for these two voltages are NOT regulated like the 5V rail is so they will nominally read higher as the post above explains well.

#6 7 months ago

Thank you DumbAss You certainly don't live up to your name! Very good and sensible reply, and thank you to pins4u as well.

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