Hello everyone,
I recently got this Keithley 2001 that would not power on.
I checked the fuse and found it was blown so went inside to investigate.
The fault was easy to spot as it had burned the PCB right below the power input jack.
Two SMD resistors (R123 and R250) got so hot they charred through the board. (Shematics and Pictures attached)
Obviously I want to save the analog board and thankfully this is the least densely populated area.
R100 reads open so the thermal fuse in it probably got triggerd, was this heat transfered from R123 and R250 or is R100 involved in the fault?
I suspect VR100 went short and overloaded these resistors, Q528, Q101, R102 and R103 seem fine so I doubt VR101 was directly involved.
The transformer thankfully appears unaffected so it does not seem like the fault lays on the secondary side, that inspires some hope.
How do I clean this board properly to check the traces?
Any insight into the cause of this disaster?
What is the appropriate cause of action? Desolder all components in the general area?
PS: I know all Electrolytics in this meter need replacement but I dont want to invest into a new set of caps until I can power it on to check the precision analog section.