Bally and stern boards are not compatible,There should be a single letter with a dash and numbers on that board.Google pinball power supply board with those numbers on the board

Early Bally and Stern solenoid driver boards (SDBs) are interchangeable. As in your case it isn't so uncommon to find Stern SDBs in Bally machines and vice versa when it was all that operators had on hand to swap in.

There are minor differences in Stern board revisions. As you've noticed your board doesn't have the HV fuse since Stern mounted it on the back of the display/lamp door panel.

Make sure the F2 fuse on the rectifier board is 0.75A fast blow, and not a slow blow.

Use the below schematic for the High Voltage section of your Stern board.

Flight 2000 Solenoid Driver Board schematic

I had a Stern SDB in a Bally Supersonic machine I just worked on. I added a fuse for the HV, did the ground mods and re-capped the board. Works perfectly.

Can you please post a clear picture of the bottom right area of the board showing details of the model and revision?

The schematic I posted above I hand modified some months ago when I was repairing a board identical to yours and couldn't find any matching schematics. The Stern Flight 2000 schematics had the right circuit but some of the resistors in the high voltage area are not marked with resistor numbers so I added them according to the board resistor locations. However R57 and R58 already exist on that board (Stern accidentally printed them twice on the board) so they then changed the resistor number locations on the next revision board.

The attached upper schematic matches the resistor locations on your board, the lower schematic is Sterns fix for those resistor numbers on the next rev board. See the markings in red to see the differences:

F2K_SDB2a.png

Hmm, this muddies the water a little.
The following pictures come from ebay.

Board #1 same as yours. No front of board revision. Back of board has PCB revision "D"

Stern SDU100 B432 Rev_
Stern SDU100 B432 Rev_
Stern SDU100 B432 Rev_

Board #2 same as yours. No front of board revision. Back of board has PCB revision that's hard to tell

Stern SDU100 B432 Rev_
Stern SDU100 B432 Rev_

Board #3 next version board, front has a sticker with revision "J". Back of board has PCB revision "F"

Stern SDU100 B432 Rev J
Stern SDU100 B432 Rev J
Stern SDU100 B432 Rev J

I am rather surprised to see that Stern put a current limiting transistor in that circuit.
Q24 performs a shutdown if the output voltage goes too low. Also surprised to see it is a 2N3904.
A 2N3904 has a VCEO of 40V. WTF? Seems the current limiting transistor needs a voltage limiter. They should have used a 2N5551 there.

I need to do the math on this one and see what the R51 voltage drop is but still think using such a small voltage rated part in that circuit just isn't a good idea. Time to do an analysis on that one.

Any objection to using a MPSA42 transistor instead (VCEO of 300V)? Since they were a common transistor in these games used on the display boards.

PCB date code 44th week of 1979.

For some weird reason they printed that bottom left PCB date code upside down on the other two boards..

Actually when Stern moved to that solenoid driver board design they did away with the HV fuse all together since it looks like the 3.3 ohm resistor at R59 is there to act as a fuse.

For reference, the picture linked below roughly shows where Stern were fitting the 1/4 amp fuse on the back of the display/lamp door (it's under the red card) on their very early games which had solenoid driver boards that exactly replicated Ballys High Voltage design (minus the fuse on the SDB).

https://www.ipdb.org/showpic.pl?id=6471&picno=73733&zoom=1

But in all honesty most of us repairing these boards have come across countless units where the HV fuse has not protected the circuit and we find the HV transistors blown/shorted aswell as some resistor being burnt out.

Here is how I added a fuse to my Stern SBD. One small trace cut on the back and then I tacked on to the bottom of the test point. Normally, I would not grab the test point as a take off point, but it physically worked the best here and the rest of the board has seen better days anyway.

20191121_214603 (resized).jpg

Does not seem like the current limiting function on the stern driver boards works as intended. The later games with the current limiting hv driver board do not have any output fuse and I have seen the entire HV area and a display get burnt and charred to a black crisp.

The stern SDB with the extra HV output fuse off the board was used in the earliest SS games that used the driver board SkiDave posted a picture of.

R59 is actually part of the current limiting circuit. If the output is shorted - you will see a high voltage at resistor R59 left side but a shorted (ground or somewhere much lower) voltage at the right side of R59. Transistor Q24 picks up on this voltage differential and starts pulling down the base voltage of the main series pass transistor - Q21 (via Q22). This starts to turn down (or off if short is bad enough) the output voltage from Q21. Of course, that was the apparent idea behind the current limiting circuit but their implementation is somewhat convoluted.
What they should have done was forgo the entire idea of varying the brightness (at least using this method), gone with more traditional method of biasing the series pass transistor and ran with that. From there, you can actually use a fold back current limiting circuit that actually works. Practicing 20-20 hind sight on somebody else's design is always a wonderful thing!

The upside to fold back current limiting is it essentially shuts down the series pass transistor Q21. Downside to fold back current limiting is the increase in power consumption in the Q21 biasing components. If the circuit is designed properly then the circuit should be able to stay alive (but turned off) until the user fixes the problem. *If* it worked right then fusing would not be required. But if the components residing in this biasing region aren't sized appropriately then you will have one component after another failing often causing an avalanche of failures.
Components of the current limiting circuit include R59, R74, R75, CR22 and Q24. Biasing for the voltage regulation circuit is R51. This same resistor is used as the input to the current limiting circuit.
In case of a short circuit and everything is operating as it should - R51 gets the entire input voltage dumped across him. Just looking at this one component, R51: If input voltage is 190V and Q24 can switch the entire load as it should then current through R51 = 5.8mA. A 2N3904 can switch up to 200mA (his voltage rating is another issue). Power being dissipated by R51 = 1.1W. R51 is rated at only 2W, I can see R51 only lasting a few minutes before he starts cooking himself. As R51 gives up the ghost then the voltage adjusters AND current limiting are taken out of the picture. Since Q23 is then pulled out of the picture then Q22 turns on again which then starts ramping up the output voltage from Q21. Both voltage and current limiting are out of the picture now so the end result of Q21 being fully turned on would not be a pretty sight.

Editing for the input voltage of 230 instead of 190:
R51 current = 6.97mA. Power dissipated by R51 = 1.6W so R51 dies quicker with a proper 230V input instead of 190V.

BTW, time to change the tile of this thread to "Stern Driver board Help"

BTW2, looking at your solenoid driver board picture in post #8, you need to add a touch more solder to pin 9 of the J2 pin header.