I have a #WPT and here is the situation:

1. I am missing an entire lamp column (03 - IC-U15)
2. A lamp socket was broken and dangling and I think very likely shorted (now replaced)
3. When I measure the pin on the board for the broken column it measures different than the other pins when in "All Lamp" test mode (So I am pretty confident it is on the board) It has voltage but it is maybe 25% of the others (it fluctuates so it is hard to pin down exactly)
4. I had previously measured the transistor and it measured weird so I replaced it (it now seems to be the same)
5. I had previously measured the small 47ohm resistor and it measured 0 ohm so I replaced it (it now seems to be the same)

I reinstalled it and it still doesn't work. I remeasured the voltage on the pin and it is still much less than the others (however it still has some voltage). I traced all the traces in the circuit and they all connect. The diode seems to measure right, the transistor matches the others (however I am not 100% sure how to properly measure this, I am using diode on my multimeter and just checking it matches the others) and the resistors seem to match. I am kind of stumped as to what to check next (or recheck) and would love some help. Here is the circuit. I don't see any obvious damage and the transistor is getting 18v.

Screenshot 2021-08-14 101053 (resized).png

Just a note that during "Column Test", on a working column I measure about 8.5 VAC on the pin and on the not-working column I measure 2.5 VAC.

So I am wondering if I ordered the right IC (sorry that is what I meant by transistor).

So I just pulled the board again and tested everything again.

The only differences I found was that the 6.8k resistor measured 7.2k, that doesn't seem like a big difference to me but maybe.

Also, when measured the IC on U17 (working) I got:

2->5 = 2.5v
4->5 = 2.5v

On U15 I got:

2->5 = 1.4v
4->5 = 2.5v

So now I am thinking it may not be the right IC (or I got a bad one?).
Screenshot 2021-08-14 111438 (resized).png

Here is what I got from Marco which seems to be the right part number:

0814211108 (resized).jpg

0814211105_HDR (resized).jpg

To be clear, the low voltage on Pin 2 is me measuring with the board out of the machine and my multimeter on "diode" and looking at negative/black on 2 and positive/red on 4 or 5. The 6.8k resistor is not in that test, I am just directly testing the legs of the IC. I have never been 100% sure how to test this so I may be doing it wrong.

I am guessing I would need to put the board back in the machine and test the input voltage to leg 2 during a test, correct? I will note that I do have connectivity between leg 2 and the resistor and between the resistor and pin 6 of the chip.

If my understanding is correct pin 2 of the IC is the activation signal from the program and pin 4 is the clock signal. Essentially there is an "and" gate in the IC that needs both pin 2 and pin 4 to be high. What is weird to me is that I am getting any voltage out at all. If either pin 2 or pin 4 wasn't getting a signal then nothing would get out. Getting 25% of the voltage seems like it must be the IC but it is brand new.

Also, I did change R139 and it is super tiny and SM. I am pretty sure I got it but it is a variable. I tested conductivity between R139 and ground and R139 and leg 1 and they both work. I also read 47ohm across the resistor.

Let me put it back in the machine and try some live tests...

I tested it everyway I could think of and all the inputs are okay but the output is low and the ground seems different. I retested the 47ohm I reinstalled and it is properly grounded. I think it is just a bad IC. I am going to buy another and try it again.

I checked the output of U9 to both U17 and U15 and they are the same as far as I tell. I checked all the inputs to U15 (pin 2,3,4) and they are the same as U17 but the outputs (1 and 5) are different. Pin 5 is about 25% and 1 registers 0v but on U17 it is like .25v. It seems like it has to be on the IC itself. Since the ground was not registering I though maybe I hadn't grounded the new resistor right but I double checked it and it is a solid circuit back to the IC.

In any case, thanks for your help. I will need to wait a week or so to get the new IC.