Do that. You'll be glad you did.

LTG : )

On the classic sterns and ballys, that 48VDC circuit has a 7 amp slow blow fuse on the rectifier board.

No. Check what fuses are in the pin you are dealing with. If 2 2/1 it would be okay, if 5 or higher, than no. Sorry.

LTG : )

Indeed you are going to need a lot more than 3Amps of 43VDC. You have both flippers and slings to consider that can fire simultaneously or in rapid sucession. You will maybe need a 10 Amp 43V supply designed operate at 80% constant load where your peaks will be short a duration over 7 Amps. An 8 Amp supply expected to operate at close to 100% is a poor design.

Slightly more conventional route might be to get an Antek AN-3216 transformer. It has two 16v taps, so if run in series, it should give 45VDC once rectified (16vac + 16vac) * 1.4 = 44.8vdc .

They are rated for 9.4 amps and cost only $36.

Antek claims the transformer can output 20% more that it's rated output.

http://www.antekinc.com/details.php?p=614

http://pinballcontrollers.com/index.php/products/power-supplies

Does your meter or Oscope log?

Do you have a Kill-a-watt?

Will you have multiball where EVERY pop/slingshot/flipper could possibly be activated at once?

If you will have multiball you are going to need a lot more than 10A. If your volt meter has a peak hold feature and can handle 10A current measure just lift the power in lead to a coil and check what that coil draws for peak current. You will be surprised. Put your meter in where the 7 amp slow blow is and do the same. You might blow your meter fuse for this measurement.

If you don't have the types of test tools noted by vid1900 you might not be properly equipped for your project.

In effect you are "feeling" that the Bally designers have got it wrong with their present design. I believe you are incorrect, and if you attempt to go lower on solenoid power, you will have poor results and a dangerous design creating unnecessary smoke.

To make a rough calculation, figure 2A for every coil with the flippers always on, drawing 4A. You have flipper crazy players where the flippers are constantly operated with the ball in the pop-bumpers you will will be drawing 6A spiking to 8A or more.

I also have a comment regarding your selection of Nixie tube displays. While this provides a nice retro look you will need some high voltage for the tubes. Also beyond the $8 per tube price you will need the specialized circuitry, mountings and another power supply.

A more economic, and cost effective way is the use of off the shelf LED displays which could permit the use of the original harness, common mountings and voltages fitting with your power supply. You also get a color choice.

If you decide to do that you must also calculate the capacitor based on the current a solenoid takes.
Remember Williams has a 50VDC circuit, which measures 70V. But a 100MF is not enough to keep the DC ripple steady. As soon as some current flows it becomes 50V.

I would buy a transformer with a 43VAC secondary, and then rectify it with a bridge. It then becomes 43V PDC.

No way. He's using the Nixies b/c the machine came out of the Star Trek MIRROR universe (as in the 'Mirror Mirror' episode). They exclusively use Nixie displays in the Mirror universe, as LED displays are too wussy for the Empire.

You can find Nixie power supplies on Ebay fairly cheap, that take 12V in, and produce ~170V out. Depending on the current output, you may need one for each display.

A design by committee! A Pinside triumph.

The orig Bally power supply has no problems putting out 170v for the old displays or Nixies.

But if I'm understanding John's direction, he might be trying to design something he can sell, and not rely on the old Bally supply at all.

For solenoids - you want a big iron core power supply with lots and lots of current. Just use a simple 48V transformer. These are not cheap in the high current range but if you take the cheap way out, you will nothing but problems in the future.
Possibly something along the lines of this:
http://www.antekinc.com/details.php?p=540

For conversion to DC, just use a simple bridge rectifier (I would go with discrete, heat sinked TO-220 type diodes rather than a GBPC type bridge).
For simple rectification with resistive load (yeah, I know it's really an inductive load...) - the final voltage and current outputs are VDC = 0.90 x VAC and IDC = 0.90 x IAC. So, the 48V transformer becomes close to 43.2volts of pulsed DC. Pulsing is fine, at 120Hz - the coils are too slow to react to this.

The multiplier of 1.414 comes into play only when you are using filter cap on the output - and it would take a heck of a filter cap for the current draw from these coils. I wouldn't even attempt it.
Switching type power supplies are not designed for this type of intermittent high current draw - not sure how long one of these would really last in this use.

The AC voltage supply is specified at 49 volts. The solenoid voltage is specified at 43 VDC. A correction is due as the fuse for the 49VAC is a fast blow 5A not 7.5ASB as a previous post indicates.

48VDC is a common voltage used in the telephone system but not on this Bally Star Trek.

So a power supply of: 80% times X = 5Amps is what you need.

No, 3 amps is not going to do it and 5 amps isn't either.

There isn't a 3/16 amp fuse under the playfield. The only fuse under the playfield is a 1ASB for the flippers.

The 3/16 amp fuse is for the HV on the Solenoid Driver/PS board at a nominal 170VAC to improve display life. Is sufficient power to drive the Nixie display units. If you are eliminating the Solenoid Driver/Power Supply board, then you will need a separate supply for the HV.

Don't forget to route some 43VDC to the MPU -- it will not boot without it.

You will also need 20 amps of 7.3VAC if you eliminate the rectifier board. You have to have this for your lamps. You can go to all LEDs and reduce the current draw. But since is a mirror project you may need to keep the lamps. You also have to have this for the MPU cross-over circuit. It has to be AC for your Lamp Driver to Operate, unless you are going to eliminate the lamp driver with a new design. Pulsed DC might be an alternative, but I haven't looked at that possibility.

As an afterthought, and something to reconsider, the Bally linear Rectifier Board and circuit will outlast computer ATX power supplies. A rebuilt rectifier board with new high current bridge rectifiers, heat sinks, trifurcon connector pins and you will have a very reliable pin component not reliant on a cooling fan.

Not just the fan, but the crummy caps.

Every time I replace an ATX it is ALWAYS the caps that have exploded. Even on Seasonic or Antecs.

I'd love it if for once the fan was the reason the PS died, LOL.

I agree .. it also seems that the power ratings are over-stated on some brands of supplies.

Efficiency and Power = almost always overrated.

http://hardocp.com/reviews/psu_power_supplies/

I wouldn't go that route -- You would need a pretty hefty cap to do this (think $25 or more). The recharge current spikes into this filter cap would be phenomenal. It's just adding another thing that can go wrong with already quite simple and reliable supply. Just use a big transformer along with big diodes and be done with it. Don't skimp here or you'll regret it later.

for my DIY pinball I'm just running a meanwell 48VDC / 10A for the high power coils. works perfectly.

ATX psu for 3.3(20A)/5(20A)/12v(70A).