Hello guys.
My R3361B began showing a pronounced vertical instability.
While looking at the CAL signal (30MHz / -20dBm) the trace was randomly jumping up and down in a 5-8 dB range. Same for every input signal.
During some work I made on the rig (PSU and CRT modules recapping) I had to move/dismount/rotate/drag the unit multiple times..
In one of these movements I had to drag the instrument towards me and 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 3/4 cm hitting the table edge right on its bottom front part.
This has been the effective moment since the instability began to show up.
I decided to take the RF input section apart, and....
oops! What I have found inside was that there was no solder joint between the LPF (THP118) and the coupler (THP202) units!! (see the first attached picture).
I've soldered them together and the S.A. is now stable again. During the fix I've found a solder drop inside the unit... I though it was a residue of my fix. It was not: it probably was the original joint that simply detached from the traces.
Can anybody confirm/comment my assumption? Does anyone have access to (or memory of) a pristine unit and tell me what the original configuration really is like?
Have I tampered the unit with?
Thanks.
Emanuele.
NOTE: a similar post was published some days ago in the "test equipment" section of the forum but it didn't receive much follow up (it was in wrong place... - my fault!).
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