Re: TZ Ground Short Issue

Yes.  
Just to check, you did this in the switch diagnostic test mode?
The banded end of the diode is towards J206?
You must have replaced U20?
Then yes, it should do this.


Excellent. Yes I did replace U20 and it was in diag test mode so I
could watch the switches fire. Every switch closes properly.


J206-2 to J208-9?  No the solenoid does not fire, but you should hear a beep
from the pin audio indicating that the switch has closed.


It did beep and I saw the closed switch


I don't see how, but I will go with that.


LOL


I am not clear from your question, if you are reading these voltages on the
pins of the CPU board, or the female connector plugs with the wires going to
them?


I'm reading from the connector plugs when disconnected. I went
through and took voltage measurements of my plugs in various states,
here is what I have found:

NOTE: Assume all plugs are connected unless I specify disconnected.
All tests are on the female plugs not on the headers on the CPU board.

Test 1: J212, J206 and J208 disconnected (Boot states check fuses
F114, F115 IIRC)

J208: Pins 1-5, 7-9 (all others 0) - 4.2 volts
J206: Pin 9 - 4.3 volts (all others 0)
J212: No voltage

--------------------------------------------------------------
Test 2: J206, J208 Disconnected (boot states check fuses F114, F115
and opto power)

J208: All pins minus 6, 4.3 volts
J206: Pins 7 and 9 4.3 volts (all others 0)

-------------------------------------------------------------
Test 3: J208 Disconnected

J208: Pins 1-4 - 4.7 volts
Pin 5 - 4.3 volts
Pin 6 - nothing
Pin 7 - 5.2 volts
Pin 8 - 4.7 volts
Pin 9 - 4.8 volts

--------------------------------------------------------------
Test 4: J206 Disconnected

J206: Pins 1-6 - 0 volts
Pins 7 and 9 - 11 volts
Pin 8 - 0 volts

With all connectors plugged in I am see the following switch numbers
lit up:

Row 1: 81
Row 2: 72
Row 3: 73, 83
Row 4: 24, 74, 64
Row 5: 75, 85
Row 6: 76
Row 7: 87
Row 8: Nothing

I don't like that J206 is reading 4.2 V DC on the plug itself pins 9 & 7,
when mine is reading 12.9 VDC.

Just to check, this is taken with plugs J206 and J208 disconnected from the
CPU board? And this is the voltage on the plug itself with ground connected
to the pin braid?

Yes.

If so, I am not certain what this means. Please try checking all those pins
on J206 again for AC. This is important.

I am not seeing AC voltage any more.

Wires 9 & 7 are columns 8 & 7. They are connected to the clock. Hours to
column 7. Minutes to column 9.

Do you have the original Williams clock boards, or a retrofit? If they are
aftermarket, I am not familiar with their voltages.

I have the original clock boards installed. They have LEDs instead of
the bulbs installed, not sure if that makes a difference.

If you do not measure any AC on any of the wires in plug J206, then I see
nothing from the playfield that is causing your U20 to fry.

I have no balls in my game right now. I have the new 10 opto
replacement PCB made by GLM. It has a 12v light lit and it is showing
14.4 volts on that connector. I have been working with Tony as well.
Thank you both for all of your help so far.

Hugh



.

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