I recently serviced a Supersonic pinball machine from Bally. It was particularly unstable and unreliable. The owner wanted to replace all the original boards with new ones to take full advantage of his machine.
I will not describe all the procedures here; this can be found on pinwiki or other forums. I will only mention the most important topics.
SAFETY FIRST: Remember that a pinball machine is a not a toy. It has different high voltages: 43 VCC, 190VCC, 230VCC and 230 VAC.
Do not attempt to repair a pinball machine when it is power on.
Even when the pinball is powered off, there is still 230vac on the filter. So always make sure the power cable is unplugged.
1 Power Supply
The really first check is to make sure the ground of the plug is well connected to the ground of your pinball machine (leg, door, side rail, interior space of the backbox and ground of all boards).
With your meter in “continuity test”, it should beep when you hit the ground from the plug and the ground from the pinball.
2. Transformer
Make sure the transformer is set to 230V.
There should be a strap between leg 4 and leg 5 of the transformer
There should be a wire on leg1 and a wire on leg 11 (230V)
Leg 7 is for 240V
Leg 12 is for 220V
3. Rectifier board
The Bally rectifier board is really the first board to be replaced. Most of the time the header pins are burnt out, the bridge rectifier are undersized, and the ground path is very bad (and requires multiple straps).
SAFETY FIRST: On most Bally I’ve seen; the plastic cover was missing. There are 230Vac and 230 VCC on this board. If you have the original board, make sure you have this protection in place. On the PinStar rectifier board, a protective cover is provided. It also has 3 LEDs indicating that the 12V is ON.
General Illumination (GI) consumes lots of current 20A. That’s a lot for fuse clips. On the Pinstar board B-67, the GI is split in 2 paths. This reduces the stress on the fuse clips (from 20A to 15A). And in case of short circuit, there is only fuse that is blows. This way, you will know if the short is located in the playfield or in the backbox.
The Pinstar rectifier board has also a pin dedicated for the Lamp board (J1 pin 3).
I also recommend buying new housings for J1, J2 and J3 and replacing all the pins with new onces.
4. Solenoid
Now that the power board is renewed. The next step is to renew the Solenoid board.
The 5V is indeed the most important voltage in this machine.
On Bally the 5V is obtained by a LM323 or 78H05 that can deliver 3A to 5A.
unfortunately, these regulators are obsolete. And a regulator like the LM7805 can only deliver 1.5A.
Be aware that the ones you find in China are probably counterfeits.
Pinstar offers two solutions.
The B-22 (Deluxe) board uses two regulators. A switched regulator that reduces the input voltage from 14V to 7v. And then a low dropout regulator that delivers 5V 5A with less heat dissipation than the 78H05.
Less heat means more reliability.
It also use Mosfet transistors which are reactive then Darlington.
There is a fuse on each transistor. This helps to isolate the problem when a solenoid is defect.
To reduce the cost, the B-22 (Standard) board will only contain only one regulator. A switching LM2678 5V 5A.
The Pinstar solenoid board has a freewheel diode for each transistor. This will prevent the transistor from burning out when the freewheel placed on the coil fails.
SAFETY FIRST: If you own the original Solenoid board. Please, make sure you have the plexiglass safety shield in place. The PinStar board will be equipped with a safety board for HV (High Voltage).
5. Mpu
Now that we have improved the voltages. It’s time to renew the most important board: the MPU.
The Pinstar BS-285 MPU board has many advantages.
No proprietary chip, so it can be repaired by anyone
a single ROM for all games: no need to get the ROM for specific game and mess with jumpers
No more battery leaks
Credit, test, and coin button: very practical when you don’t trust the wiring of the door
LEDs for each voltage (5V, 12V and 40V)
6. Lamp board
LEDs are brighter, more responsive and draw less current than standard lamps.
With the original board, the thyristor does not have enough current to keep the LED on. The Leds then flicker.
The PinStar B-23 board has some resistors in parallel to avoid flickering.
It also has a test LED on each thyristor, which allows you to detect any failure (always on or always off).
7. Sound board.
Finally, this Supersonic pinball has also a PinStar b-51 sound board included.