I'm getting 28 volts DC at my coils, and as a result, my Andromeda is way too rowdy. The ball hits the glass constantly, and I'm surprised I haven't broken a drop target. I confirmed that the transformer is configured for a 115V AC source, with COM connected to 1 and 4 connected to 4A. My other DC voltages are good.

Is this normal, and if so is there a trick to taming the coils? I thought about putting a 20W cement resistor in series with the output of the bridge rectifier, to drop the voltage down.

I have the power supply / transformer assembly here at my desk, so I can experiment without risking the game.

I'm also reading 14 volts AC at the 24V test point. I'm swapping out the middle bridge rectifier to see if this helps.

Okay, I found the root cause: the transformer' secondary winding is putting out 34 VAC, instead of 28. I guess I'll hit up eBay for a replacement.

Yes, the existing bridge rectifier tested fine once I pulled it. I swapped in a new one with a 35A rating. My DMM is a Klein Tools MM200, not too fancy but it did cost me about $50-60. I tested for DC and AC voltages the same way: with the black lead on the ground TP, and the red lead on the 24V TP. I just used the DMM's "FUNC" button to switch between DC and AC.

I've got a Bally transformer / PSB (Skateball), so I'll look at what voltages I see there. I'm hoping that Bally and Game Plan used the same transformer (edit: nope).

[EDIT] I just re-checked, see pic below.

My biggest problem was that the ball would smack the glass every time it came out of the trough (into the plunger lane), and sometimes even jump up between the glass and the playfield and get stuck (!). I solved that by putting a 5 ohm, 10W cement resistor in series with the return lug.

The airballs aren't too surprising, since Andromeda is loaded with drop targets mid-playfield. I just wish I could calm down the flippers a bit. I've adjusted the EOS switches so that they open as soon as possible, but the flippers are still too strong. I know, nice problem to have.

Sorry, I forgot to mention that I measured this at the flipper coil, with a game in progress (everything connected).

Brady Miller's manual does indicate that the "24V" can be +/- 6 volts, so I agree that it's within "normal" range. I wonder if I could add a cement power resistor in series with the 24V output of that bridge rectifier, to drop it down.

OK, I am reading 14.57 VAC with my cheap DMM, but I think that's just because it's a rectified sine wave - this is not a true DC signal.

IMG_7464.jpg

I'm getting 122 at the outlet, and the transformer is wired for 115. So that alone accounts for a 6% boost in coil power. No option for 120.

Yes, I want to reduce the coil power at the flippers, pops and slings. It's an early SS pin, so there's no way to adjust coil strength via the settings. The game is at about a 4.5% incline.

I'm leaning toward adding a rheostat in series with the 24VDC output of the bridge. What power rating would I need for a 2.5k ohm rheostat?

PSU-1 schematic:

http://www.pinrepair.com/gp/manuals/gp-sch-psu1.pdf