HP 3582A Spectrum Analyzer doesn't scan

[bristpi176]

Hi folks,

I am back with another piece of test gear in need of help.  I have an HP 3582A spectrum analyzer that doesn't scan.  It shows "overload" on the screen most of the time but no input is coupled.  When I turn it to its Cal position, I can hit the reset a number of times before it will show the expected display.  It will then scan for about a second and the display will freeze up.

I think a big hint (what do I know) is that it will only accept front panel inputs when you reset the machine.  In other words, I can change any front panel setting and it won't be implemented until I hit reset. 

I'm not sure what else you would want to know to help put me on the right track so please let me know.  Thanks for your help.

Thanks

[Cubdriver]

i have one of those in my repair queue, but haven't looked at it yet and don't currently have access to it so will be of limited help here, but as with most older instruments I'd start by looking at power supply rails and filter caps, and reseating boards.

The service manual is available as a pretty decent quality scan for free download from Keysight.  https://literature.cdn.keysight.com/litweb/pdf/03582-90004.pdf?id=2442835 might get you there, otherwise go to keysight.com, click on the 'support' tab, select 'keysight product support' and enter 3582a in the box to get the literature on the instrument.  The service manual PDF is 28.13MB.

Good luck with it!

-Pat

[bristpi176]

Here's what I've done so far. 

1.  I pulled and inspected all the boards and cleaned them and the inside of the machine up.  This thing must have been run at a sand pit.  Lots of crap inside. 
2.  Cleaned the front panel and exercised all the switches.  See sand pit above.
3.  All the lights on the power supply boards are green, so without breaking that one down it looks like its getting power properly.
4.  I followed the initial troubleshooting in the service manual, removing boards one at at time to see if the problem would clear.  It didn't show me anything.

I don't have the riser boards to run those tests that require access to the boards.  I'm more of a board swapper if truth be told.

Thanks

[Cubdriver]

Do you have a scope to look at the power supply rails for ripple?  The power supply indicators will tell you it's there, but not necessarily if it's good.  Failing filter caps can give all sorts of grief by letting noise through and into digital circuits.