Sir Richard . . . . .
What it does seem there that you have yourself is a ferrite "dog bone" contrawound input inductor / line filter that has both of its fine magnet wire windings open, either :
- 1 . . . Folded, spindled or mutilated
- 2 . . . Burnt / or / blown open . . . . . ( burnt, being from a hot soldering iron dragged across by a pereson of either low intellect or intent of imparting damage upon.
The 5V would be indicative of the incoming input voltage and then encounterig the open winding and finding no circuit path over to pin 2 and into that via just to its left and then routing to the other side of the PCB..
Pin 4 is being connected to the ground plane that is
GOING ALL OVER that side of the PCB with its multiple connections.
Pin 3 , with it having a VERY-VERY low Ω
2 path to ground via the BLUE winding, therefore must NOW also be open with it reading a 1,5 V " sneak voltage " on it .
Find a replacement or rewind with two separate 40 + 40 turns windings of 38---42 gauge insulated magnet wire, as is being shown.
ILLUSTRATION . . .
View attachment 49020
73's de Edd . . . . .
Really fat people are really, really hard to kidnap !
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