Push the diag button on the MPU. What does the mpu diag digit show after that?

Volt meter logic probe on CPU P40. If it is 5vdc / HIGH, your reset section is working. Reset failures in System 6-7 is rare, they almost never fail.

Side note... i did a Solar Fire MPU the other day and the ROM labels where wrong from the factory!. They had IC20 and IC17 labels mixed up. I have seen that mistake on Black Knight too.

Your reset is fine if p40 is 4.8v.

Treat it like a non working 6802 computer at this point. I would remove the driver board and boot it up on the bench with the test ROM. If the test ROM does not run. Check the CPU external clock at CPU p37 (should be about 0.8MHz or 2.5vdc or so).

If the clock is good, swap in a new known good 6808 CPU

Still nothing i would maybe suspect the PIA. A lot of times you can tell if the PIA crapped the bed if the a bunch of outputs are floating.

Still nothing pull the ROMs out and run the board with only the CPU installed. Check every address and data line. See if any are not pulsing like the rest (buffer failure, i know the address lines are buffered, i forget if the data is buffered in s7).

Still nothing start investigating the chip select for the test ROM at IC17... It should at least pulse somewhat after a valid reset.

Remove the driver board and see if the LED behavior changes. A faulty interconnect will lock up the MPU.

If it blinks consistently one time when you start up , that means the CPU isnt completely locked up and the main PIA is probably OK.

Verifying the ROMs are good would be the next least invasive step. The test ROM is a good idea too. You need one burned on 2532 for system 7.

Following this Thread to, hopefully, see a happy ending!

Make sure your Blanking isn't active.

Blanking is like a safety check to make sure the software is running so outputs, like solenoids, do not lock on when the computer is crashed out.

The blanking will only go high if the display PIA is active. The blanking circuit looks for one display PIA output to be changing state. If it stops changing state, it is assumed the software has crashed so the blanking goes low disabling PIA controlled outputs like lamps and solenoids.

The blanking section itself can fail, but low blanking is typically a symptom of a non working MPU, not the cause.

Radical solution : Get rid of it and sell it to me

Haven't seen it mentioned but we can assume that the ROM sockets are of good quality and the 40 pin interconnect has been properly serviced?

Do you have a test eprom? Looks like the reset section isn't working.

Use Leon's test rom, you won't need the logic probe (or a led and resistor) to see if the reset section is working. At least you will know which board is causing the problem. The double board setup is a pain to work on, but at least with Leon's test rom you can do a pretty exhaustive bench test.

Are you running Leon's test rom with the other roms installed? Take those out, it sound like one of those is bad. When the led's flash and go off, the board is trying to boot. It could be a blanking issue too, but I think that Leon's rom will still flash the led's on and off if there is a blanking problem. You installed the test rom at IC17, correct?

Are you running the test ROM in the game with all the connectors attached?? The test rom is a bench thing. Check your solenoid fuse also..... With all respect...it seems you don't know what you are doing. It might be a good idea to send your boards to a experienced technician (John Wart Jr, Barakandl - Andrew, ..... )

Not really. With the test rom installed the display should be flashing 0 and the leds should be blinking on and off. It's been awhile since I worked on a system 7, lately they have all been system 6 and lower.

Did you burn the test rom yourself or purchase it? I believe that someone stated it before, it should be a 2532 for a system 7.

Ah, you were probably referring to the onboard 7 segment display at the CPU board and not the displays in the backbox. My bad. I'm sorry for that. I am repairing circuitboards for 30 years already. Dead pinball circuitboards can be divided in roughly 3 categories:

-Those who died due to age or a short circuit somewhere in the playfield
-Those who died by leaking batteries (can be hard to repair)
-Those who have been butchered to death by some "Handy Harry" (makes me sad)

Maybe I saw the last category too many times. If my car is broken I bring it to a car repair shop, there are skilled people there (skills I am lacking in this area) with the proper tools (which I don't have); I will probably screw up and pay a bigger bill in the end when ignoring this and doing it myself anyway. But we might disagree here and I think this is not what you want to hear.

As I already said, I repair a long time already and I even created my own test ROM's as Leons' is a bit unreliable with memory testing.

I will try to help.....

-system 7 boards need +12V ( Reset circuitry) and +5V (Logic)
-Pin 40 needs to be "1", if "0" the /reset signal is active and the (test)program will go nowhere
-you can check if Leon's test ROM is running at addressline 6 pin 15 at he 6802/6808 CPU
-the program is not starting due to a defective 6802/6808 CPU
-the program is not starting due to a missing clock signal
-the program is not starting due to bad IC sockets
-the program is not starting due to a defective chipselect circuitry (LS138) or check traces if there have been leaking batteries.
-the program is not starting due to a defective chip jamming a dataline or addressline. Leon's test ROM needs only a few chips to run. You can remove both memories and both PIA's. Is the program starting now (a6 pin 15)? If positive.....re-install the removed chips 1 by 1 to find the culprit.
-The onboard 7 segment display is controlled by PIA 1 (display) via a TTL BCD decoder. This might fool you. The program is running but this PIA or BCD decoder prevents to show you anything at the onboard 7 segment display. You can swap this PIA with one from the driverboard or so if socketed.
-.....................

Good luck and I won't bother you anymore in this thread

Is there data buffers on system 7? I know they took them out during parts of 6, but if not check those.... I find bad buffers quite often. The address buffers less likely to fail.

Sometimes the 5101 will shit out so hard to mucks up the data/address bus.

When i really get stuck i pull of the RAMs, PIAs, ROMs, and only have the 6808 installed. In this state it is pretty easy to check every address, data, chip enable etc. As they all will be pulsing.

9 times out of 10 when these boards are dead, all it needs is all new IC sockets, headers, and AMI PIAs replaced.