Alright, I broke out the multimeter and tested the components around DA24 and DB24. Here are closeup photos of each area:
https://drive.google.com/file/d/1-oE2yIr8bD5s_TAYNtKUfiARwBXFRDKY/view?usp=sharinghttps://drive.google.com/file/d/1-oFUKbdxmCZiVx788v7J6nGEGJ5vrAdX/view?usp=sharingDA24 has a diode and a transistor.
The diode passes 0.548V in forward bias and 1.2V in reverse bias. The diodes on the DA adjacent pin line circuits read 0.459V in forward bias and 1.498V in reverse bias. When measuring reverse bias, the meter slowly ticks down on Pin 24, but slowly ticks up on the adjacent pin line circuits.
I didn't test the transistor.
DBA24 has a diode, two resistors and a capacitor.
The diode passes 0.543V in forward bias and 1.103 in reverse bias. The diodes on the adjacent DBA pin line circuits read 0.546V in forward bias and 1.520 in reverse bias.
The first resistor reads 0.992 k-ohms. The equivalent resistors on the neighboring pin line circuits read identically.
The second resistor reads 467.3 ohms. The equivalent resistors on the neighboring pin line circuits read 480.5 ohms and 472.1 ohms
I get no reading (0.L) on the capacitor but I get the same reading from the capacitors on the adjacent circuits. I've confirmed that I have my meter set for capacitor measurement.
Next, I fired up my scope and connected the probe to the Pin 24 slot in the socket, and the probe ground to the ground rail on one of the voltage regulators.
https://drive.google.com/file/d/1-qDY7CFEWXEguWFJWJUJte4KmGCZWluW/view?usp=sharingI set the scope to run a Single capture on a Pulse trigger. Then I ran the Pull Up & Down test, which recorded a failure on Pin 24 as usual.
https://drive.google.com/file/d/1-b-3rKoqAFJofaKdOW0EEt-VtZFd4F6M/view?usp=sharingThe scope recorded two pulses. The first pulse is 1.9V for 91 ms. The second pulse is 4.86V for 4.4ms. Pics of the measurements along with using the Cursor to read the two pulses are here:
https://drive.google.com/file/d/1-e5qdwZdNxc6TOgRSGUJXUdLwfVFcacg/view?usp=sharinghttps://drive.google.com/file/d/1-hR0ODK3aayRSn1o3TM2NtekO0Mychml/view?usp=sharingNext, I moved the probe up a few slots in the connector to Pin 18 so I could read how a healthy pin measures.
Again, the scope recorded two pulses. The first pulse is 1.9V for 88ms. The second pulse is 4.8V for 26ms. Pics of the measurements along with using the Cursor to read the two pulses are here:
https://drive.google.com/file/d/1-Z4rGP8WFBcDFCPCSKJN6KTzfW7duw0s/view?usp=sharinghttps://drive.google.com/file/d/1-X8etj2KHX1pYuOnXtCLWJQAAhVKJoDv/view?usp=sharingIt looks to me that there is some variance in how the two DA24 and DBA24 diodes measure compared to the equivalents in the circuits around them, but I'd have to pull them and measure them out of circuit to be 100% certain, correct? As far as the scope goes, it looks like the first pulse is pretty much the same but the second pulse is cut off abruputly for Pin 24 compared to Pin 18.
Where should I go from here?