Common problem is the ground connection at the Aux Lamp Driver Board (ALDB).
When you measure power on that board be sure to connect your black multi-meter lead on TP2 of the ALDB. If you don't measure 5V at TP1 of the ALDB then check the ground crimp at pin 15 of the J1 connector on that board.

If it's ok, then the next likely issue is you have a bad connection on the lamp strobe #2 signal. It comes from the MPU board at J1 pin 8 and goes to the ALDB at J1 pin 3.

Nope, that would affect solenoids only, not lamps.

Also the one ground pin (14) is not enough, you should add at least one more ground wire to the other two pins, or if your board definitely grounds to its bracket like my ‘81 EBD, add one there. That single ground pin from the factory is always cooked to heck.

I 100% agree with this and I do the same thing by also wiring the ground wire to one of the other ground pins to share the load.

I don't have the LE schematic, but the first release EBD schematic lists it as a solid grey wire from MPU board to Aux lamp driver board.

Note, pin 1 is at the top of the connectors of the MPU board, meanwhile pin 1 is on the bottom of the connectors of the aux lamp driver board just to make things confusing..

Have you got a logic probe? Need to next check if you're getting active signals to the logic chips on the board and if they're responding accordingly.

BTW, can you post some clear high res pictures of the board in case there's something obvious we might notice?

Ok, thanks for the reminder of what's been done.

How are you checking continuity of that wire from J1 pin 8 of the MPU to J1 Pin 3 of the ALDB? If you're checking from wire connection to wire connection, it doesn't tell you if the terminals are making contact with the pin headers so you really need to test beyond them and check from board to board. i.e.
Resistor R1 on the ALDB to resistor R79 (Bally MPU board) or R40 (Alltek board). When you measure from the side of the resistors going to the pin headers at each board, you should read zero ohms to verify you have good connectivity of the signal from board to board.
Otherwise if you do happen to have a logic probe, check that you're getting activity at pin 9 of U1 on the ALDB.

Cool, ok hookup power to the logic probe - i.e. the black logic probe lead to TP2 (Gnd) and the red logic probe lead to TP1 (+5V) respectively on the ALDB.

Then touch the probe tip on pins 9, 4, 5 and 12 of U1 of the ALDB. Lets see if the control signals from the MPU board are reaching the board.
If you can tell us what the logic probe LEDs indicate at each pin and also provide a photo of your logic probe, we can determine what the probe is telling you.

Don't forget to carry out @frenchmarky's suggestion in post#4 - i.e add a loop wire from the white-black wire at connector J1 pin 15 to pin 14 at the aux lamp driver board.

If there's a "TTL/CMOS" switch, set it to TTL and if there's a "Pulse/Memory" switch, set it to Pulse.
Otherwise post a picture of it so we can see what settings it has.

Put both logic probe switches opposite to how they're pictured.

To delete pictures, edit your post, hover over the thumbnail attachment and click on the "X".

PinSide_Delete_Picture.jpg

Set the logic probe to TTL. Do the indicator results change? You are getting activity to all the required pins though.

Do me a favor, at the aux lamp driver board, hook up a jumper lead to test point TP2 and touch the other end of the jumper on the metal tab side of any of the SCRs on the aux lamp driver board. Does doing this illuminate any playfield lamps?
For example if you ground the metal side of the Q1 SCR, the left lane 10k lamp should light, does it?
Grounding the metal tab of Q14 should light the 112k bonus lamp.

Just for your sanity, can you try the grounding SCR test on your main lamp driver board? i.e. if you ground the metal tab side of the Q8 SCR on the main lamp driver board, the #13 ball lamp in the rack should light.

Can you post a picture of the back of the ALDB? It doesn't have any burnt ground traces does it?

The bare braid wire running to all the feature lamp sockets on the playfield is 6.5V power. The tip if the lamp sockets is grounded by the lamp driver board to illuminate the lamp. So try grounding the tip of one of those ALDB driven lamps such as the left lane 10k, 30k and 50k lamps. Do they light?

Lamp_Socket_Controlled.jpg

Ok, using the same ground point location you just tested with, touch the other end of your wire on the metal tab on some ALDB SCRs.

What about grounding a SCR on the main lamp board? Eg Q8 for the #13 ball lamp in the rack.

It almost sounds like the playfield block connector to the backbox that ends up at the ALDB is disconnected.

And the lamp worked?

The SCRs on both lamp driver boards basically complete the ground circuit to the lamps.
You've grounded the lamp sockets and the lamps illuminate.
You've grounded the metal tabs of the SCRs which connect directly to the lamp sockets and they didn't illuminate.

So it sounds like an intermediate block connector that goes to the ALDB is disconnected between the playfield and the backbox.

have you check the 2 fuse holders under the playfield . i had a problem on the controlled lighting on an LE and it was bad fuse holder .

Denis

Can you post some clear pictures of the burned wires on the connectors?

The two orange/red wire connectors on the ALDB (J2 and J3) running to the playfield lamps have black protectors covering the connector wiring ends. Slide those black covers up or down to expose the connector wire terminals. What happens when you ground some of those metal terminals? Do their respective lamps on the playfield illuminate? i.e. grounding the:
J2 pin 4 (Red-White wire) should illuminate the 70k left lane lamp
J2 pin 11 (Red-Black wire) should illuminate the Specials left lane lamp
J3 pin 3 (Blue wire) should illuminate the 50k Inlane drop target lane lamp
J2 pin 15 (Red-Green wire) should illuminate the Extra Ball left lane lamp

If the lamps illuminate then you need to find out why ground isn't reaching the common "cathode" leg to all the SCRs on the ALDB.
If the lamps don't light at those two connectors terminals, then ground the end tab of those particular lamps at the lamp sockets to make sure the lamps are working. Presuming lamps are good, then find out where you have a break in the wiring between the lamp sockets on the playfield and those two connectors on the ALDB.

Make sure where ever you connect to ground actually has good continuity to ground.