Hi Guys,
Long time lurker but it is my first post here. I'm trying to repair a complex multilayer board at work. It is part of a preamplifier system for an NMR chemistry system ( 400Mhz).
In this circuit there is a 50 ohm reference that gets compared to the NMR probe to match the impedance of the resonance frequency of the nucleus under test.
The problem with this unit is that the 50 ohm reference resistor lifted off of the pad. Usually simple enough fix but it also took the pad right off. Usually I would just hardwire it to the next component inline but the problem is that the pad was connected to a very small blind via that also lifted off under the force.
I have another of these units that is working available for testing and for the life of me I'm not able to trace where this blind via goes. I spent a couple of hours searching with my multimeter in continuity test mode and couldn't find anything.
Is there a way to repair these kind of blind via by scraping down to the next layer ? I'm not entirely sure I get how a blind vias are manufactured. Or is there a way for me to find where this via may go?
Any help would be appreciated as this replacement board is in the 7000$ range for a new unit. It would be sad to pay that much only for a lifted pad....
Thanks for you help !