After full recapping of the PSU and CRT modules of my R3361B the instrument began showing a pronounced vertical instability: looking at the CAL signal (30MHz / -20dBm) the trace was randomly jumping up and down in a 5-8 dB range.
I initially suspected a side effect of my recent recappings, but that was not the case.
Long story short:
during recapping I was forced to move/dismount/rotate/drag the unit multiple times..
In one of these movements I had to drag the instrument towards me:
the two front feet inadvertently went over the edge of the table; it has
been as if the instrument had fallen from a height of 2/3 cm hitting the table edge right on its bottom front part.
This has been the actual moment since the instability began to show up.
Stated that:
- the input LPF-coupler assembly is located just behind the input socket in the right bottom front part of the unit - just where it took the hit;
- the LPF (THP118) and the coupler (THP202) are each built as gold stripes laid down on a ceramic substrate; the two parts are connected via a very thin solder joint crossing between the two ceramic wafers..
