HP 3582A , issues want to repair ?

[KD0CAC John]

I just ended up with this Spec. analyzer at no cost , and looking to see if I can get enough info the repair .
I am not an engineer , electronics guy , but do residential electrical auto motive and hobby / ham radio build & repair .
Most of the things like this I repair are by finding others with similar issues , then see if I can apply there fix to my issues , works a lot and this helps to learn .
There is almost no reaction to any manipulations of any controls on front except power button .
One of the smaller sub-power supply boards had 5 test points and they were labeled ,
TP  +15 F
TP  +15
TP  -15
+15F LED - on
+15 LED - on
-15F LED - on
-15 LED - on
+5 LED - on
TP  -15
TP  +5F
Most would start with 39.99 volts for less than a second then drop over time [ 1 -2 min. ] to as low as 0.082 volts .


 
 

[ManateeMafia]

If you are not aware, the manual can be found here

http://www.ko4bb.com/manuals/97.76.44.130/HP_3582A_Spectrum_Analyzer_Service_Manual.pdf


Near the end is service group 11 for the power supply boards. HP did a good job listing test points so you should be able to get some good measurements. There does appear to be some high voltage on at least one of the supply boards.

[KD0CAC John]

Thanks for the link , I was going to do that latter .
I'm leaning towards a short pulling down the the values on that board , desoldered most of the components and tested , I found no failures .
Off to your link .   

[ManateeMafia]

Of note, not all supplies share the same ground. Some are marked with an "I" for isolated.

There is also a page with resistance winding values for the transformer.

Good luck!

[RNA]

I had the same issue with the scrambled text.  It ended up being a dodgy ram ic.  I had to buy a signature analyser to detect it.

[KD0CAC John]

Could you give more detail ? do not have one of those .

[PaulAm]

PS issues can be a common problem.  Either shorted tantalums or shorted or open filter caps.  An ESR meter might be a good investment.

At a certain point in time when test equipment started to incorporate microprocessors a means of identifying problems called signature analysis was developed.  It is relatively simple, but I'll let you find the theoretical papers and read them.  In short, you put the instrument into a special test mode, hook up a signature analyzer to the specified points and then use a probe, also connected to the signature analyzer to probe various points.  The signature analyzer calculates a value (a signature) and displays it and you compare that with the value for that IC and pin in the service manual.  When you find something that doesn't match, you've identified the problematic component without having to track through the schematic and understand exactly what the part is supposed to be doing.  Theoretically, of course.  Sometimes it gets a little more involved, but you generally get into the problem area.

HP made several signature analyzers, I have a 5004a and a 5005b.  The Sony/Tektronix 308 data analyzer will also compute the same signatures (if you get one of those, make sure you get the pods with it).  Signature analyzers can generally be found pretty cheap since they're completely useless for anything else.  I got my 5005b for $12 out of a buck a pound box at a hamfest.  I paid $20 for the 5004a in nonworking shape, but it only needed a filter cap.  The 308 tends to be a bit more expensive since it's an 8 bit logic analyzer too which is useful for small projects.

[KD0CAC John]

I have several LCR & ESR meters , took some components off 1st board that I suspected and all checked out .
That is why I was thinking issues on other boards .
In the service manual it said to pull all power consumption / boards and then probe all power boards for correct readings ,
Then replace one board at time till issues reappear - the fault should be in the board that causes off readings .
Thanks for the replies .