Blackbelt specifically. The Right Kickback is sometimes weak. It only occurs for a few seconds after the Right side or Left side switch gates are activated, the ones opposite the top two flippers. When this happens the relay makes a buzzing noise if the kickback is activated soon afterwards. No issues with anything else controlled by the solenoid expander. And the kickback functions normally during the rest of play, no buzzing, powerful.

The switch for the kickback isn't on the same row or column as the gates in the switch matrix.
The lights activated by the gates are the Normally Closed side of the Solenoid Expander
The Kickback is on the Normally Open side.
The diodes on the 48v wire the Top Left Lights and the Kickback share have been replaced.
The Solenoid Expander light is working perfectly.

I suspect it's undervolted when all of the lights are on, however i'd expect the other solenoids on the Normally Open side to act the same in the same situation and they do not.

I'm mostly just wondering if this is a design issue as opposed to a failure. However, a previous owner managed to set most of the solenoid flasher lights on fire. It's actually quite impressive.

Yours will look be arranged differently. In testing the Solenoid Expander I re-mounted the lugs, added more and spaced them out more. It was too easy for wires to touch, which seems to be common for this playfield. I meant to redo this to make it a little neater, oh well.

My diodes were backfeeding and blowing the 11v fuses. I replaced those and IIRC I was missing the diode on the bottom. Also quite a few more diodes were backfeeding throughout the playfield. I imagine we had a similar failed component to cause the fires.

se (resized).jpg

Does your relay buzz in test mode in the all lamps test?

I fixed mine by just applying contact cleaner liberally to related connections and the relay.

Mine did work correctly for about a week after I applied contact cleaner to the inside of the relay and connector pins on the relay, but I did a lot of other things during the same time period.

I'm assuming yours' also will fire weakly about three times in a row then put out a full strength shot, and this only happens for about 10 seconds after the right gate is activated.

My next steps are to:
Remove a top left solenoid light, check effects.
Check condition of FU1 5A fuse.
Check condition of playfield fuse.
Check TP4 voltage. 43vdc out vs 49vac in
Replace the bulb on the solenoid expander with the highest and lowest resistance bulbs i have.
Check voltage and amperage going to coil after the right gate switch gets activated follow by the kickback switch.
Clip the capacitor on the right gate switch, check effects.
Install a capacitor on the kickback switch
Replace diodes on the coil
?Replace the coil with one that needs less voltage.
?Install a capacitor on the kickback coil.
?It could be that a 43v Capacitor is nearing failure. I don't see a capacitor on the schematics. It doesn't look like the 43vdc output has a capacitor. However, nothing else has power issues anyway. If anything the 43v line is too strong.
?There is a 48v relay on the pinball control module. I think it's unrelated.

Does anyone have a new power supply or transformer? Or both?

x - (No effect) Remove a top left solenoid light, check effects.
x - (Fine) Check condition of FU1 5A fuse.
x - (Fine) Check condition of playfield fuse.
x - (Perfect) Check TP4 voltage. 43vdc out vs 49vac in
x - (No change, left an LED in) Replace the bulb on the solenoid expander with the highest and lowest resistance bulbs i have.
x - (I removed the solenoid expander bulb and nothing changed, very strange)
x - (Amperage is lower after a right gate activation, even if the relay seems to work correctly. Measuring voltage makes it so the relay never properly latches) Check voltage and amperage going to coil after the right gate switch gets activated follow by the kickback switch.
x - (Already did this) Replace diodes on the coil
- Clip the capacitor on the right gate switch, check effects.
- Install a capacitor on the kickback switch
? - Replace the coil with one that needs less voltage.
? - Install a capacitor on the kickback coil.
? - It could be that a 43v Capacitor is nearing failure. I don't see a capacitor on the schematics. It doesn't look like the 43vdc output has a capacitor. However, nothing else has power issues anyway. If anything the 43v line is too strong.
? - There is a 48v relay on the pinball control module. I think it's unrelated.
? - Does anyone have a new power supply or transformer? Or both?
- Remove right side and 20k lamps
- Replace right side and 20k lamp diodes.

Other operators efforts:
x - Replaced SEB board
x - New connector and re-flow at MPU J9
x - Removed (LED's) from the top left series bright lights (same transistor, other SEB phase)

Repair guide:
http://www.techniek.flipperwinkel.nl/ballyss/rep/index3.htm#expand
Done - Header pins on the solenoid expander board may have cracked solder joints. Re-flow these header pin solder joints.Done - In-series diode going to the power lug of the coil may be broken, missing or reversed.
Done - Diode across the lugs of the coil may be broken, missing or reversed.
Done - Switch contacts on the solenoid expander board's relay may be pitted and may need to be filed (or the relay replaced).
Done - The solenoid expander board's MOC3011 opto-isolator may be bad. Replacements are available from Jameco (part #95020), or replace with NTE3047.
Done - Diode on the solenoid expander board's relay may be broken or missing.
Doubtful - The lamp under the playfield next to the solenoid expander board may be burned out. Replace with a new lamp. Without this lamp, there isn't enough load for the SCR on the lamp driver board to activate the solenoid expander board's relay.
Doubtful - The lamp driver board's SCR that controls the solenoid expander board may have failed. See Locked-On or Not Working Feature Lights (lamp driver board) section for details on how to test the SCR.
- The 6.5 volts provided by the power supply's rectifier board BR1 bridge may be failing. The 6.5 volts DC provided by BR1 powers the
- feature lamps. If this voltage is low, the solenoid expander board's relay may not function correctly.
- The power supply's rectifier board R2 resistor (25 ohms 5 watts) may be broken or open. Check it with your DMM set to ohms.
- Connector pins on the power supply's rectifier board may be burned or tarnished. This will create resistance which will lower the 6.5 volts DC provided to the lamp driver board. If this voltage is low, the solenoid expander board's relay may not function correctly.

comments:
The relay isn't latching properly when the relay fails to fully activate the coil. The relay sparks and hums.
The relay still doesn't latch correctly with the kickback coil detached.
Problem is likely then related to the relay or SEB board.
A lot of you have replaced both, so it's not necessarily that.
Bad transistor?
The other solenoids are slightly leaky, about 0.01 amps were measured going through kickback coil when other solenoids were activated. But this is probably normal.
I don't have the Bright Lights Field Kit, Although I might install one now (Does your playfield have any scorch marks?)
I've tried everything I can think of to get a similar failure for another solenoid, hasn't happened.

Updated 5/5
x - (No effect) Remove a top left solenoid light, check effects.
x - (Fine) Check condition of FU1 5A fuse.
x - (Fine) Check condition of playfield fuse.
x - (Perfect) Check TP4 voltage. 43vdc out vs 49vac in
x - (No change, left an LED in) Replace the bulb on the solenoid expander with the highest and lowest resistance bulbs i have.
x - (I removed the solenoid expander bulb and nothing changed, everything was still functional, very strange)
x - (Amperage is lower after a right gate activation, even if the relay seems to work correctly. Measuring voltage makes it so the relay never properly latches) Check voltage and amperage going to coil after the right gate switch gets activated follow by the kickback switch.
x - (done) Replace diodes on the coil
x - (no change) Clip the capacitor on the right gate switch, check effects.
x - (no change) Install a capacitor on the kickback switch
? - (doubtful) Replace the coil with one that needs less voltage.
? - (doubtful) Install a capacitor on the kickback coil.
? - (doubtful) It could be that a 43v Capacitor is nearing failure. I don't see a capacitor on the schematics. It doesn't look like the 43vdc output has a capacitor. However, nothing else has power issues anyway. If anything the 43v line is too strong.
? - (doubtful) There is a 48v relay on the pinball control module. I think it's unrelated.
? - Does anyone have a new power supply or transformer? Or both?
x - (no change) Remove right side and 20k lamps
x - (doubtful) Replace right side and 20k lamp diodes.
x - (seems like no change) add a lamp in series with solenoid expander after phase a/b line diodes and before pin connection to SEB
X - (measured 6.4) check 6.3vac voltage
tbd - check connectors between all lamp related parts. i know i sprayed them with contact cleaner, seeming like this is it.

Other operators efforts:
x - Replaced SEB board
x - New connector and re-flow at MPU J9
x - Removed (LED's) from the top left series bright lights (same transistor, other SEB phase)
x - Installed bright lights field kit

Repair guide:
http://www.techniek.flipperwinkel.nl/ballyss/rep/index3.htm#expand
x - (done) Header pins on the solenoid expander board may have cracked solder joints. Re-flow these header pin solder joints.Done - In-series diode going to the power lug of the coil may be broken, missing or reversed.
x - (done) Diode across the lugs of the coil may be broken, missing or reversed.
x - (done) Switch contacts on the solenoid expander board's relay may be pitted and may need to be filed (or the relay replaced).
x - (done) The solenoid expander board's MOC3011 opto-isolator may be bad. Replacements are available from Jameco (part #95020), or replace with NTE3047.
x - (done) Diode on the solenoid expander board's relay may be broken or missing.
x - (done) The lamp under the playfield next to the solenoid expander board may be burned out. Replace with a new lamp. Without this lamp, there isn't enough load for the SCR on the lamp driver board to activate the solenoid expander board's relay.
tbd - The lamp driver board's SCR that controls the solenoid expander board may have failed. See Locked-On or Not Working Feature Lights (lamp driver board) section for details on how to test the SCR.
tbd - The 6.5 volts provided by the power supply's rectifier board BR1 bridge may be failing. The 6.5 volts DC provided by BR1 powers the feature lamps. If this voltage is low, the solenoid expander board's relay may not function correctly.
tbd - The power supply's rectifier board R2 resistor (25 ohms 5 watts) may be broken or open. Check it with your DMM set to ohms.
tbd - Connector pins on the power supply's rectifier board may be burned or tarnished. This will create resistance which will lower the 6.5 volts DC provided to the lamp driver board. If this voltage is low, the solenoid expander board's relay may not function correctly.

Comments:
The relay isn't latching properly when the relay fails to fully activate the coil. The relay sparks and hums.
The relay still doesn't latch correctly with the kickback coil detached.
Problem is likely then related to the relay or SEB board or something before it.
A lot of you have replaced both, so it's not necessarily that.
Bad transistor?
The other solenoids are slightly leaky, about 0.01 amps were measured going through kickback coil when other solenoids were activated. But this is probably normal.
I don't have the Bright Lights Field Kit, Although I might install one now (Does your playfield have any scorch marks?)
I've tried everything I can think of to get a similar failure for another solenoid, hasn't happened.
I think this is related to a lamp or something that controls a lamp

Update 5/5 #2
With only the lamp driver and 48v power going into and out of the relay it still has the same failure related to the right gate.
I have only pins 1,2,3, and 9 connected.
It doesn't spark as much but it still doesn't properly latch. Problem is definitely not a solenoid or anything on the NO or NC circuits.

Update 5/5 #3
Problem is almost certainly insufficient current/voltage to activate the relay.

It's an issue with the lamp part of the circuit. If the solenoid expander is disconnected the lamp still won't flash at full brightness when the right gate is activated.

The misfire only happens when the top left flasher flashes. There seems to be little rhyme or reason as to when or why the top left flashers flash. They don't always flash after a right gate activation and don't always flash with the kickback, but they sometimes do and this causes the issue.

The coils and flashers controlled by the solenoid expander will fire even if their lamp phase is disconnected. This shouldn't be possible. When a phase is disconnected the relay then just tries to latch to both the NC and NO side at the same time.

New list of possible issues in order of likelihood:
Leaky flash/feature lamp diode (There's only 50+ to swap)
****There's probably a clever way to test this. I think disconnect CJ10, CJ11, and CJ13 and then jumper CJ10-6 from the connector
Insufficient voltage to lamp driver board (dirty pin or broken connector/solder)
Failed lamp driver SCR
Timing/clock/crystal failed
Bad programming/design

I disconnected all the flash lamps besides the solenoid expander and still had the same issue with the relay not properly switching between NO and NC.

I grounded the MPU screws using physical wire instead of using the foil covered cardboard or whatever is in the backbox. No change.

I don't think it's a power issue or a failed SCR because it only occurs when the top left flasher and kickback are activated at the same time. But this is what I'm checking next.

I still don't understand how the kickback/saucers can even attempt to fire when their phase is disconnected. Although it is AC and the waveform is analog, so maybe the SCR is just reading the low/dissipating voltage and firing anyway.

I doubt the lamp next to the SEB is necessary anymore considering how much resistance our dirty connectors are causing. If anything the SEB probably needs the extra amps. But this is just a thought.

I think the easy solution is going to be delaying the right kick back activation signal somehow.

I took it apart to clear coat the playfield. so the resolution to this is going to be a little delayed.

I swapped the kickback coil with the knocker coil. It works well enough. Don't forget to add a diode if you do that. I doubt I'm going to figure out a better solution.