I found this instrument on internet for sale, having a failure
with the selftest showing integrator failure.
I made a bid on it and it was accepted so after some time I had this in front of me.
At start up it indeed showed the selftest failure and temperature at 0 degrees.
I opened the unit and did a visual scan for any lose parts or broken parts, this was unsuccessful.
During the period the instrument was open I suddenly had a moment were it responded like it worked but this did not last very long and failure came back as before.
Looking into the service manual which I found on the internet
i decided to dismount the main board and while doing so I found another board
below the main board. I also checked this one visual and then I found a bad
soldered connector. I did solder the connector again and reassembled the whole
The instrument was working fine again.
A very nice portable spectrum analyzer able also to do VSWR measurements and insertion measurement up to 3 GHz.