Adventures in HP 70000 series repair.

[Raindog]

Thought I might share this with the group. I recently took possession of a nice HP 70000 series spectrum analyzer, upon receipt I noticed it had a few issues but was still functional. Starting from knowing little to nothing of this series I downloaded all the manuals I needed. Since I was going to add more modules my first challenge was to figure out how to set the module dip switches for the appropriate "rows" and "columns" and WHY the were set the way they were. Next was to acquire spare SMB jumper cables and any necessary semi-rigid hard line interconnects. Next was to purchase two replacement RAM back-up batteries for the HP70206A Graphics display and the HP 70900A local oscillator. Next was to figure out why the I/O check lights were always illuminated on the HP 70001A and the HP 70206A. After much experimenting the issue wound up being that one of the cables I received with the unit wasn't a real HP-MSIB cable, just a standard 37 pin DSUB cable. I wound up DYI'ing my own cable with the assistance of this site https://www.rbarrios.com/projects/HP-MSIB/ now I'm up and running! No more I/O issues!

I didn't take any images of my repair process because it was mostly dead RAM back up batteries and a bad MSIB cable. Battery replacement on the 70206A is nothing more than removing the battery compartment door and replacing it. The 70900A replacement was done by removing the unit, removing the 8 cover screws, then position the unit so the front of the oscillator is on your left. Remove 3 retaining screws and spacers, remove the small ribbon cable on the top left, then carefully remove the board, the battery is on the left side. The batteries replaced were a Tadiran TL-5104/S for the 70206A and a Tadiran TL5104/P for the 70900A. Hope someone here finds this helpful.

This unit is certainly a major upgrade for me from the HP 853A / 8557A you see next to it, lastly will be a tracking generator to test filters and antennas without the need to use my HP 8644A. Now I need a Bourbon on the rocks. Cheers!

[eb4eqa]

Glad to have helped!

That weights a ton but it is a fine instrument.

Regards,
Roberto EB4EQA
Www.rbarrios.com

[genesilvernail]

Great thanks for your post on battery locations. I just acquired a 70k system and know very little but am learning. Before pulling the 70900a board i did a pretty thorough hunt for the Easter egg, peeking ans snooping finding nothing. So ith your input a openned it up and still no battery....what the @@!$$. Looking closer I finally ound where the battery...was. Someone removed it and it never got replaced... on order will do.

The thing that puzzles me the 70k came from a gv-surplus auction, not a private party and my thinking remains why was it removed. Why the 70900A scrutiny? it doesn't show up on the address screen while the balance of modules do.

Again thanks


K7QHO/Gene