HP8592A Screen Help

[Telecom Green]

Folks,

The very helpful Jules Omega has suggested that I ask for help regarding the display on this kit.

I powered it up, nothing went "bang-puff", but the screen looks totally pixilated and unreadable to my eyes.

Can anyone advise if this is a normal state, or if anything is adjustable, please?

Photos below.

This is part of a large inventory of other kit listed in my other thread (below)

Thanks

Rob

[RogerEvans]

I don't know the internals of this spectrum analyser but if the display is based on dynamic memory (DRAM) then what you see looks consistent with one or more ICs having failed.

Roger

[Telecom Green]

Originally Posted by RogerEvans

I don't know the internals of this spectrum analyser but if the display is based on dynamic memory (DRAM) then what you see looks consistent with one or more ICs having failed.

Roger

Thank-you. Is this item simply useful for "spares and repair" only if this is the case? Jules Omega has advised connecting the input and outputs together on the front. Is there anything else I could do?

Rob

[Julesomega]

Connect the calibrator output to the main input using just the shortest possible bit of wire, this will give an idea of the overall performance. Your photo seems to show that the crucial YTO is ok.
The instrument cleverly calibrates the frequency tracking of the YTO at start-up, using the internal frequency reference oscillator

[Radio Wrangler]

Amongst the dots, you can see a proper trace, graticule and annotation. Likely most of the CPU/display board - the big one down the right hand side of the instrument as you look at the front panel is working. I suspect a memory or logic device on this board. There may be an exor function for inverse video text.

The display CRT module is a Panasonic TV monitor type in most of the 859x family of analysers and you can, on some variants, set the analyser to 525 or 625 line formats so you can video record the picture.

David

[Telecom Green]

Thanks, all.

Here is the photo of the screen under test. There are traces and letter visible. I have dealt with many faulty displays on phones, and this seems to resemble a degrading "ribbon to LCD" situation. it's probably something quite different. I will also try and post a short video clip.

[Telecom Green]

Screen Photo With "Peaks"

[Radio Wrangler]

Don't worry about the spectrum analyser analogue sections, calibration or the CRT module. What is visible on that screen points squarely at the CPU/graphics card.

David

[Telecom Green]

Originally Posted by Radio Wrangler

Don't worry about the spectrum analyser analogue sections, calibration or the CRT module. What is visible on that screen points squarely at the CPU/graphics card.

David

Thanks. Does this mean that it is ultimately fixable? I am deep in unknown territory here!

Rob

[Radio Wrangler]

Probably. But no guarantee. Well worth the effort to find out.

I didn't get involved with the 9x family (R&D project name 'Hornet') of analysers until the E suffix variants which were quite different in various respects. However, if there's a 'U' in the serial number after the 4-digit datecode (years after 1960, then week number) then it was built within 100 metres of my desk.

David

[Telecom Green]

A quick snap. Does this say anything else about the kit?

[Julesomega]

Option 021 = HP-IB Interface

[Radio Wrangler]

28 plus 1960 = 1988, and week 28, built in the USA which will have been the HP plant at Rohnert Park, just off highway 101 about 50 miles north of the Golden Gate Bridge. On the edge of the Californian wine growing area. It's now an indoor go-cart track and a tomato growing business in the old HP buildings.

David

[6AL5W-Martin]

that spec owns a video output at the back.
It would be nice to know if there is a correct video signal or not.

[Radio Wrangler]

The 856x series of portable analysers use vector graphics on electrostatic deflection CRTs. Many tubes have reached end of life and replacement stocks were exhausted many years ago

The 859x series, however, use standard TV video signals to a magnetically deflected CRT in a bought-in display module. You can use a video monitor or video fecorder on that BNC output.

I used to have my 8591E in the radio shack running a macro of scanning each amateur band in successtion. Video went on coax from the analyser to the TV in the lounge. All I had to do is select Aux input on the TV remote and I could see the conditions on all the bands! Lazy, or what?

The 6x family was much more expensive and had a wider dynamic range log amp (and slelected low phase noise YIGs). Some customers insisted on vector displeys and real time analogue plots at high enough scan rates, saying they couldn't see some artefacts which the analogue displays didn't allow you to see. But the 9x family had some tricks the 9x (Codename Hornet) couldn't do. The 6x were derivatives of the 8566/8568 analysers (codename 'Doomsday box'). After many aborted replacement projects, the 6x family were replaced by the PSA. The 9x had a less disastrous replacement programme resulting in the 'Mosquito' family.

The 6x replacement projects ate up far more time and money than would have developed a successful replacement had the goals been far-sighted enough. All the delay did was to allow Rohde and Schwarz to get ahead with a superior range of top end analysers. For many years HP/Agilent was trying to play catch-up. I'm not sure how things compare nowadays, 20 years have gone by since I was party to new product plans and a couple of generations have gone by, so I'm well out of date. I bought an 8566B for myself to restore, and that seems to do everything I need. If the CRT goes, there are aftermarket LCD kits for them.

Anyway, I strongly suspect that the OP's 9x box can be fixed by tracing the video signal backwards on the CPU card.

Sticking a TV monitor on the TV video BNC would be a good move to get a bit more confidence that it's logic/memory on the CPU card.

David

[Telecom Green]

Thanks so much, folks, for the advice.

Would the test lead connection be a simple male-male co-ax?

Rob

[Telecom Green]

Originally Posted by Telecom Green

Thanks so much, folks, for the advice.

Would the test lead connection be a simple male-male co-ax?

Rob

P.S. Which Output of these? Monitor Output? One of the Aux?

[Radio Wrangler]

monitor output. It's composite video with blanking and syncs.

Switchable between 525 lines 60Hz and 625 lines 50Hz on a menu, somewhere

David

[Julesomega]

That's wonderful news for me too, as I have an 8563E which I'm supposed to be selling for a colleague but you have to wait for nighttime before you can read the display. Should be able to feed the composite video into an older flat screen TV via a SCART adapter I've got somewhere.

[Julesomega]

There are 5" screen display units for use with vehicle reversing cameras, they take a video input on a single RCA Phono jack and will also allow you to watch DVDs (just need a small 6–32V dc supply unit). Several from ~£12.50 on eBay