(Topic ID: 300409)

No Flicker but All 7 Flashes

By oldschoolbob

12 days ago



Topic Stats

  • 10 posts
  • 4 Pinsiders participating
  • Latest reply 8 days ago by oldschoolbob
  • Topic is favorited by 1 Pinsider

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#1 12 days ago

This board was working fine. Bench tested and in a Trident game. Flicker and 7 flashes.

I pulled the board to replace the RAM for NVRAM. Bench tested before I put the board back into the game. Now I get a flash - pause - then 6 flashes. (see video):

(I have 24 volts to TP3 to get the 7th flash.)

It seems correct but what happened to the flicker?

Thanks

Bob

#2 12 days ago

maybe try without any lighting, like in the dark?

#3 9 days ago

I tried in darkness. Only thing on was my laptop and power supply. No Flicker.

I removed the NVRAM and installed the old 5101 RAM. No flicker. I swapped the 5101 for another 5101. Still no flicker.

Next I'll try it in the game.

Thanks

Bob

#4 9 days ago

This is interesting. I failed to mention the sound board was connected before. Just for kicks I disconnected the sound board and tried again. The flicker is back. Then I connected the sound again and no flicker.

All this testing is done at the bench - not in the game.

Sound board connected = no flicker.
Sound board disconnected = flicker.

WHY?

Thanks

Bob

#5 9 days ago

I just put the MPU (and sound board) back in the game. It boots fine - WITH flicker.

I don't understand why (when bench testing with sound board connected) it would skip the flicker.

????

#6 9 days ago

Rise time on your bench supply is quicker so comes out of reset faster, able to turn off the LED right away

#7 8 days ago
Quoted from slochar:

Rise time on your bench supply is quicker so comes out of reset faster, able to turn off the LED right away

Why would that make a difference if the sound board is connected or not?

I've tested dozens of MPUs and always get the flicker.

Would having the sound board connected make the rise time faster?

#8 8 days ago

Missed the part about the sound board being in the mix.

So, dunno. My answer was based on the theory of operation in the manual with the reset circuit.

#9 8 days ago

With the sound connected there is more capacitors to charge up. The voltage raise may take longer before it passes the zener diode value on the MPU. Because of that, the MPU maybe spending more time in /RESET. That would mean the LED is on longer for the "flicker".

Some of the moldy old LEDs that are barley lighting up anymore you don't see the 'flicker' or the attract mode dim glow.

#10 8 days ago
Quoted from barakandl:

With the sound connected there is more capacitors to charge up. The voltage raise may take longer before it passes the zener diode value on the MPU. Because of that, the MPU maybe spending more time in /RESET. That would mean the LED is on longer for the "flicker".

Now there's an explanation that makes sense.

Thanks

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