Author Topic: Agilent 54621A Scope wont turn on.  (Read 1475 times)

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Offline bopstarTopic starter

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Agilent 54621A Scope wont turn on.
« on: February 09, 2020, 07:21:45 am »
I was working on some stuff with my Agilent 54621A scope measuring audio signals. and then I turned it off went to do something came back to turn it back on to find it wont turn on now.
when i power the unit all the lights turn on but no display or anything.

Attached is an image if anyone can help that would be great.
JH
 

Offline Prehistoricman

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Re: Agilent 54621A Scope wont turn on.
« Reply #1 on: February 09, 2020, 01:52:37 pm »
Do the buttons/lights behave as normal? I'm thinking that the display might be dead, but all the logic still functions.

Offline HighVoltage

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Re: Agilent 54621A Scope wont turn on.
« Reply #2 on: February 09, 2020, 02:08:53 pm »
Most likely the power supply is broken.
This happens from time to time on Agilent scopes, older and newer types.
Usually they are easy to repair or to replace the PSU.


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Offline EHT

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Re: Agilent 54621A Scope wont turn on.
« Reply #3 on: February 09, 2020, 02:26:32 pm »
There is a Service Manual PDF which you'll be able to find. It has useful info such as how to test the main PSU and some other steps such as resetting the scope.

However, it would be good to have the schematic as well. Anyone know where to find that? I have a 54622D which I'd like to have the schematic for.
 

Offline fcb

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Re: Agilent 54621A Scope wont turn on.
« Reply #4 on: February 09, 2020, 02:26:36 pm »
Does look like the CRT supply - do the buttons function as before? What's your level of repair-fu like?

If you get stuck I've got a 54622A in stores that I can measure some voltages off etc..
https://electron.plus Power Analysers, VI Signature Testers, Voltage References, Picoammeters, Curve Tracers.
 

Offline JFJ

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Re: Agilent 54621A Scope wont turn on.
« Reply #5 on: February 09, 2020, 08:29:01 pm »
Before getting too embroiled in attempting to identify a hardware fault, do try a "key down power-up reset". This can often resolve  546xxx series oscilloscope boot-up problems. From the service manual:

To reset the entire oscilloscope, press and hold any softkey and switch the oscilloscope power on. Release the softkey when the display appears.
 

Offline bopstarTopic starter

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Re: Agilent 54621A Scope wont turn on.
« Reply #6 on: February 09, 2020, 10:55:21 pm »
All the buttons never turn on in normal operation. some lights turned on that I didn't know where there which I thought was quite funny.

Ill check the PSU as suggested.
JH
 

Offline bopstarTopic starter

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Re: Agilent 54621A Scope wont turn on.
« Reply #7 on: February 09, 2020, 10:56:54 pm »
I did try pressing a softkey while turning on still behaves incorrectly with all the lights on. So sadly not the fix
JH
 


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