[weblacky]

I’m nowhere near an expert, but, in situations like this where an entire section of interaction is gone, I look to see if there is some kind of multiplexing ic that controls the top-half of the bus to the chip you’re referring. You’re right that all those solder joints aren’t likely to break so evenly, where it’s possible some kind of amplifier/multiplexer/enabler/etc ic is in front of the bus and is responsible for repeating or timing the queries. Since you get 0 instead of a floating state response, it makes sense that there might be parallel lines/channels of such communication that allow queries on a wider bus.

If you can closely examine the chips that are on the lines of the IC you’re referring to you might be able to find duplicate ic components and layout that would lead you to believe there are upper and lower busses that get and assemble the entire response. you can then measure using various tools/meters to see if both parallel channel’s chips have the same basic measurements to various tests. In that perhaps the solder joints of one chip or bad or the enable line of one chip is bad or that the chip shorted out in someway where it never hears responses and always gets zeros for anything queried through it.

Then measure that same chip in the nearby parallel set/channel for a comparison. You may find an upper communication channel has an ic that does measure the same as the successful lower channel bus.