Don't measure from ground to the pins. This is AC so measure across the pins. One lead on pin 1 the other lead on pin 2. Sounds like the bridge may be bad. There are lots of topics on how to check a bridge using the diode mode of your meter. If you have 50 volts ac across the ac pins of the bridge then switch to dc mode on the meter and measure across the + and - pins of the bridge. You should have 45 to 55 vdc if not then the bridge is bad.

Thanks zacaj for catching my mistake. I edited the post to correct.

So with 52 vac at pins 1 & 2 then you need to take the board out and check the bridge. If you have schematic you can figure out where on the component side you can check the dc output of the bridge but that should be ground and the 43 vdc test point so you probably just need to take the board out, look over the traces on the back and check the bridge.

I am a little confused on what the 2518-151 board looks like so I think I will stop confusing you and let some one that is familiar with this board help. A picture of the board could be helpful.

I think the first thing I would do is unplug the connectors at the top of the board, power it up and check the test points again just to make sure the problem is on the board. Make sure you have your meter set to DC when measuring DC voltage and on AC when measuring AC voltage. check the manual for the proper voltage to be seen at each test point. With no load on the board some of the voltages will be a little different than expected and that is okay, you are looking for the presence of voltage at this point, no exact values.

Taking the board out is pretty simple. Turn the game off and unplug from the wall. Take off all the connectors and unscrew the Phillips screws holding the board to the metal plate and remove board. When you have it out post a picture of the back side of the board. At the very least you will need to reflow the solder on the connector pins, they typically crack and cause problems so you might as well do it while you have the board out. Reflow them all whether they look good or not.

I just finished a rebuild of boards for a Kings of Steel where BR1 was bad. On those boards (-54 I think) the bridges are mounted on the bottom of the board and use the metal plate as a heat sink. This one looks to be different with the bridge mounted on top and no heat sink.

With the board out check continuity from the input pins to the bridge and the output pins to the bridge. If those all look okay then you can check the bridge itself with the diode mode on your meter. If you don't have those instructions I will try to find a link to them.

I have not looked at a schematic for this board so you might want to check to make sure the 43 vdc is generated by the bridge and not the individual diodes on the left, but you will find that out when you trace input pins.

So here is the part of the schematic we are interested in for the 43 vdc. It is indeed generated by the bridge.

So pin 2 of J5 go through fuse F2 (5 amp) to one AC pin on the bridge. Pin 1 of J5 goes to the other AC pin of the bridge. Across the AC input to the bridge is VR1 (varistor, the red disk). VR1 should be open, when a large voltage spike comes in it will short and blow the fuse. Yours looks to be okay. The large 600 ohm 10 watt resistor is across the DC output of the bridge and provides a load to the circuit so it does not float open when nothing is energized. You said you checked this and it is okay.

The bridge is nothing more than 4 diodes encapsulated. To check the bridge put your meter in diode mode and measure across each diode. With the positive lead (red) on the anode of the diode and the negative lead (black) on the cathode you should see some voltage drop, something like .6 or .7 on your meter (this is forward bias for the diode). Reverse the leads and you should see open (this is reverse bias for the diode). The anode of the diode is the triangle and the cathode is the straight line. It gets a little confusing checking the bridge in circuit since you have VR1 and the resistor interacting with the readings but you should be able to see if it is good. You are looking for a difference in reading from forward bias to reverse bias of each diode. If there is no difference and there is a reading of some kind then the diode is shorted and the bridge is bad and needs replaced, if both directions read open then the diode is open and the bridge is bad and needs replaced. If they look okay and still no 43 vdc at test point 4 (TP4) and you have 50 vac at pins 1 and 2 of J5 then the problem is either the fuse, fuse holder, VR1, 600 ohm resistor or the traces themselves. You can remove VR1 for testing but that would be my last resort, if you measure open across it then it is not the problem. Just for your information, when a diode is forward biased then it will conduct and what your meter is reading it the voltage drop across the diode when it conducts, which it typically .6 or .7 volts. When a diode is reversed biased it will not conduct and you should not see any voltage drop.

Seeing the back of the board will help a lot in figuring out what could be the cause. If traces are good then it is likely the bridge. It is a 35 amp bridge probably 200 volts so you may want to source one of those. Soldering these heavy components like the bridge and high wattage resistor can be hard without a hot enough soldering iron so with the board out make sure the solder connections look good and always check continuity through the circuit to make sure everything is connected.

2818-151 (resized).jpg

You are correct G-P-E it needs to be a 200 or 400 volt bridge, I mistyped. I edited my post to say 200 volts.