If the onboard dual LEDs come on and then go off at power on, then the 6802 is operating. If it were being subjected to 114VDC, it would have been roasted in the blink of an eye.

The board doesn’t receive that kind of voltage and it can’t be made on the board.

Measure again.
Let’s see a pic of the meter and reading.
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Chris Hibler - CARGPB #31
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Don't. We all start somewhere. I guarantee you're better equipped now having had this experience.
As barakandl mentioned above, lack of blanking is almost never caused by a failed blanking circuit.
The blanking circuit is doing it's job buy preventing the software from driving the hardware into a possibly damaging condition.

The blanking circuit that Williams used (and DE too) remained unchanged from System 3 all the way to System 11.
A 555 timer is configured as a "missing pulse detector", with a specific "time out".
I've added info about the blanking circuit into the PinWiki Data East section. You can find it here to use as a reference:
https://www.pinwiki.com/wiki/index.php/Data_East/Sega#Blanking_Signal_Stuck_Low_or_Pulsing

For your System 6 MPU, the "reset" pulse to the 555 timer originates at IC18, pin 4.
IC18 is the PIA that is in the display section.
If that PIA isn't being updated so that it pulses pin 4 within the "timeout period" of the 555 timer, then blanking will be pulled low.

It's a virtual certainty that the microprocessor isn't running.
Why? There are numerous reasons. We always start with the basics first.

1. ROM images correct
2. Power correct
3. Reset signal (s/b low, and then high a split second later, sometimes hard to see with a logic probe)
4. Clock signal (the input at pins 38/39 to the 6802 can't be seen with a logic probe. But, the output clock, pin 37, can. Assume the clock is good if pin 37 is pulsing)
5. The "8T" bus buffers at IC3, 4, 8, 9, and 10 are working. These are easy to test with a logic probe. What goes comes out of the output side should always match what comes into the input side.
6. Any craptastic "scanbe" sockets replaced. This goes for any socket that doesn't tightly grip the chip legs.

That should get you started.
Press on soldier.
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Chris Hibler - CARGPB #31
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I see that the scanbe sockets have been replaced. Good.
I also see an AMI 6810 memory chip. AMI chips are always to be suspected.
You can test 6810 with the NeoLock SRAM tester, try it in a known working board, simply replace it, or use Leon's ROM which has the ability to test memory.
--
Chris Hibler - CARGPB #31
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The 555 timer will time out and blanking will be pulled low if pin 4 doesn't pulse before the timeout period.
Make sure that IC18 is both connected correctly to the data lines AND it is receiving the chip enable signals at pin 22, 23, and 24
Pin 21 is read/write
pin 34 is reset and should follow the reset signal present at the 6802
The clock signal should be pulsing at pin 25
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Chris Hibler - CARGPB #31
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Leon's test ROM should be illuminating.
It has a memory test also. It is said that it isn't a comprehensive memory test, but it's probably good enough.
Pin 4 of IC18, with a properly working MPU, will pulse with Leon's test ROM.
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Chris Hibler - CARGPB #31
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Theonlylilo
Good eye!
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Chris Hibler - CARGPB #31
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https://www.youtube.com/c/ChrisHiblerPinball - My YT Channel
http://www.PinWiki.com - The Place to go for Pinball Repair Info