HP 54645A Oscilloscope problems.

[AtypicalRabbit]

Hi, Long time watcher first post etc...

I picked up an HP 54645A for $75, it powers on. gets past the boot screen and will occasionally stay functional to run some tests.

It fails the ram test "error code 2" I can't find this particular error anywhere in the user documentation.

Also when booted in unprotected mode, while holding keys 5 &6 I get "vertical cal factors failed checksum" and "horizontal cal factors failed checksum"

I believe these issues may be NVRam related. I haven't opened it up to take a look about yet.

I'm not sure the probe that came with it is any good, but it seems to do nothing on either 1 or 2. And there's garbage on the screen when 1 is on. and I get a note "waveform data is clipped" Don't think that's a good sign.

Also, it seems to crash after a being on for a while, I say crash as the screen remains unchanged, but the buttons stop doing anything.

Let me know if you have any insight into this issue, otherwise I may be out $75

Thanks

[Hydrawerk]

There are some strange easter eggs in this scope... http://www.ebay.com/itm/Hp-Oscilloscope-54645A-100MHz-with-SPACE-GAME-Agilent-digital-storage-/111201811945

[free_electron]

the D version has tetris instead of arkanoids.
ALL digital hp scopes have this kind of easter egg.

[AtypicalRabbit]

I did find both easter eggs. They do come up.

Still unable to get this thing to do its intended job.

[NickAmes]

If you have a BNC cable, you can run the self calibration from Print/Utility->Service Menu->Self Cal Menu->Vertical. This might solve the "vertical cal factors failed" problem. The horizontal self calibration requires a signal generator, but the procedure is detailed in the manual.

the D version has tetris instead of arkanoids.

Just for the record, the 54645D has Centipede (or "BUGS" as they call it), like the 54645A.

[TerraHertz]

ALL digital hp scopes have this kind of easter egg.

Sadly, it seems my HP 54121T digital scopes do not. 
Or at least google doesn't seem to know of it if they do.

[AtypicalRabbit]

I can't seem to get it to stay "active" long enough to run the calibration. If I touch anything in the horizontal section outside of the Main/Delayed soft key it will instantly freeze and need to be rebooted.

Any thoughts ?

[TerraHertz]

Have you identified where the various RAM blocks are?
From the fault behavior it sounds like a system memory fault.
Might it be possible to just change the system RAM chips?
Or, perhaps if they are on a card that's easily removable, you could buy/borrow another card,
and try swapping?

[Ca_s12]

There are no daughter boards or the like just one single board in these. I have one that has no input on channel 1 but works fine when using channel 2. If there is anything I can do to assist you in getting yours running just give me a shout!

[AtypicalRabbit]

If anyone has a spare main board I could swap this faulty one with that would be awesome, I've called the manufacturer, and the place that last did a calibration. It's been obsolete since 2007, neither of them have parts.

[Retep]

Did you check if all power supply voltages are stable and good?

[AtypicalRabbit]

So I did as Dave would and took it completely apart. Check all the cables, re-seated both program eproms, checked for cold solder joints, cleaned 15 years worth of dust and such out of it. Then put it back together.

This time it let me run the diagnostic on lines 1 ,2 , and ext. Passed all three. Rebooted, and it works perfectly fine. I'm sure it needs some serious calibration but everything works perfectly now. Wild.

[GreyWoolfe]

ood for you getting it working.  I just did the same for a friend with a Kikisui scope.  The traces would fade out after 20 minutes.  After verifying all the power supply voltages, I wiggled, disconnected and reseated all of the connectors.  The scope works perfectly now.  Sometimes it is the simplest things.

[AtypicalRabbit]

Well, it worked for a few hours, power cycled many times, ran every test I could. Turned it off to have dinner and it is back to giving me a Ram error, refusing to go into vertical calibration mode, and crashes if I touch the horizontal controls.

No idea why it would work intermittently like this. The only thing I can think of is bad ram, or a cold solder joint somewhere. 

When it works, it will flash an icon waiting for an input, when it's being bad it doesn't flash.

This isn't fun anymore.

[casinada]

Welcome to the world of Crappy old electronics were science art and black magic converge. 

[AtypicalRabbit]

Discovery!

It will let me go back into vertical calibration mode if I disconnect the fan and let it get very hot, and it now "works" again. Lets see what happens when it gets cold again. I also forgot to flip the calibration protection switch last time, so it may have lost the data when it got cold, or voltages were not as they should be.  I don't have my DMM with me either, which is slowing this down terribly.

Is this a thermal issue with the power supply, or somewhere else. Haven't figured that part out yet.

[AtypicalRabbit]

I had it working for a good 2 weeks before it quit again, I think this may be permanent.

I get "Time interpolator initialization failure" During the boot sequence.

If anyone knows where the Time interpolator is, or has a schematic for this thing let me know. Otherwise I'm going to buy a Rigol DS1052E.

This tells me its a CMOS chip that controls the VRam and time interpolator ?
http://www.hpl.hp.com/hpjournal/97apr/apr97a3.pdf

Any thoughts ?

[NickAmes]

The fact that it worked when warmed up seems to indicate a faulty solder joint, which you already know. Have you tried re-soldering the main ASICs? I have a copy of the CLIP (schematics) for the 54645A, but I'm out of town at the moment and can't get to them until next week.

[AtypicalRabbit]

Well, it doesn't seem to want to "work when hot" anymore, I got it to allow me into the self calibration successfully twice in the last 3 days, and it worked for maybe 15 min, the second time it crashed during input 2 calibration. Haven't been able to get that far into it since.

I would love the CLIP file if you could send it to me, I don't mind waiting.

[AtypicalRabbit]

If anyone has or knows of someplace I can get a replacement main PCB Part # 54645-66503 Rev B. I'd like to buy it, this board is not repairable. 

[AtypicalRabbit]

I've repaired the physical damage to the board (I damaged an ADC when the heatsink hit something) I've replaced the M48z18-100PC1 as I thought that may be an issue.

I'm still getting a "Time Interpolator Failure" message while forcing it to show its boot sequence, as well as the "test failed with error code 2" message under ram self test.

Any insights into this would be very welcome.

Thanks

[don.r]

Hate to resurrect old threads my 54645D is suddenly showing similar symptoms. Traces freezes soon after startup or disappears completely. Fails vertical cal although cal signal is present. I have yet to test rails for ripple but the +-15.75V rails are +-15.8V which is fine. I fear it might be the ADC which unfortunately I believe is a BGA.

EDIT: PSU rails show no excessive ripple (10s of mv or less)