HP 8591C spectrum analyzer Repair ...

[barry@tnt]

..hello every one ...

       im in need of any assistance on the repair of the hp8591C spectrum analyzer , as the history of this unit it
has been parked up most of its time  before heavy use by its previous users , came in for a monitior/screen being
defective , the unit remained scraped an parked up for some years before a new screen was bought for it , at the time
when the screen was changed and the unit was first powered up some of the boards top side started to smoke , later found out
that their are some 22uf 25v tantilum capacitors that burnt an shorted on the boards , The analog interface board had a resistor an cap burnt ....

And their was another small board with just the caps shorted out ...... I have been thou all the boards for more damage but have not seen any thing else to cause a problem , so far the unit powers up with the grid on screen , software version is displayed, and i can adj the frequency span interms of numbers with the dial  , but their is no noise floor , an when connected for self calibration it runs the mode but the test fails i think the calibration output is not working an so is the spectrum for the noise floor ....

(power supply voltages all test ok except for one which was the 15v+ ... was droping to 13.8 an 12.6 at different times)
i did injected an outside 15v source but did notting to bring up the functionality of the noise floor on the spectrum ! ...

not sure if its a software problem or hardware ! ....

Any assistance in troubleshooting this unit will be greatly appreciated as i would really love to get this up an running for my
personal use !