Advantest R3361B Spectrum Analyzer vertical instability - Page 1
Forum section: electronics / repair

author: egirland
author_rank: Contributor
timestamp: January 19, 2022, 10:30:03 pm
content: 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!).

author: egirland
author_rank: Contributor
timestamp: April 28, 2022, 09:15:12 am
content: A smart guy showed me that my 1st mixer coupler indeed shows a substrate crack (see pic)!Any idea how to fix it?Indium?As an alternative do you think it is possible to put together a PCB layout by KiCad resembling the original design?I made some feasibility test with KiCad and it seems possible...Which modern substrate is electrically the closest to the original?Do I have to really use gold?

author: Maurizio1957
author_rank: Contributor
timestamp: April 28, 2022, 12:17:47 pm
content: Hi Emanuele, where do you found the schematic? I can't found nothing for the R3463 ...Maurizio

author: serg-el
author_rank: Regular Contributor
timestamp: April 28, 2022, 05:35:19 pm
content: Rose's alloy, Wood's alloy... Gold dissolves very well in solder. So rebuild with the lowest temperature solder you have.

author: egirland
author_rank: Contributor
timestamp: April 29, 2022, 10:05:40 am
content: Thank you serg-el !I didn't know about those alloys.I read wikipedia ..now I know a little more.From a practical point of view how do we use them? Same treatment as tin solder?Can usual flux be used?Any particular suggestion?About the temperature point I own a temperature controlled soldering station so I don't expect to have problems (after making some practical exercise with what is a new material for me..).

author: serg-el
author_rank: Regular Contributor
timestamp: April 29, 2022, 12:01:02 pm
content: https://www.chipquik.com/store/index.php?cPath=200&osCsid=arov5t6a51qria7tgkatfqoqg7ChipQuik AlloyThe same. Just do not call the composition of the alloy. Flux is normal.