Agilent 54622D refurbishing advice needed

[Wigo]

Hello Community,

I recently got a Agilent 54622D locally and it works fine but it needs cleaning and the broken handle needs to be fixed and the battery needs a replacement.

As a few knobs are sticky and full of gunk i tried to clean one with mild soap and an old toothbrush and it works nice. The nob is clean and after letting it dry in the sun, it appears that the stickyness is also gone.

But i need an advice on how to replace the battery. As i have not found a replacement of the CR2354 with solderjoints on it can i just solder a CR2032 batteryholder in place and use this type of battery? As both have the same voltage it should work. Or am i missing something here?

And what do i need to upgrade the firmware? Are there any "hacks" that can be done to this scope in the firmware?

Thanks and i will post pictures later this day when i am at home and can take a few.

[No.Mad]

Hi Wigo,

as a brother in pain (I also got recently turbo dirty 54622D unit) you should be really careful with replacing on-bard battery. It holds all calibration coeff. values in memory, so if you fuck up calibration is gone - if there was any.

My advice is: first measure the voltage on a battery - double, no, triple check if your multimeter is on DC voltage measurement and if you are going to place probes correctly. One wrong step and puff! - you guessed it, calibration is gone. Voltage should sit on about 3VDC. If it is, battery is fine. If it's not and it's dead you don't need to be so careful, the cal valueas are already gone. In this case just replace dead battery with holder for easy replacement in the future.

Secondly: If battery is not dead you need to add SECOND battery in parallel. This will hold up voltage as you replace the old one. So trace with continuity traces on board and find good spot to solder second battery, change old one and de-solder auxiliary one. You should be fine, but to be on safe side: hook up second multimeter (if you have one) wit DC voltage measurement mode to monitor voltage on memory. Just in case bruv.

I did not get to part with firmware but if you search "Agilent 54622D" in a forum you might find a post about it - I think I saw at least one.

I got a service manual for this particular model - if you want it just let me know.

Cheers and good luck!

[wn1fju]

What I've done in the past with these scopes is to remove the battery, solder two wires to the board, run them out the back and mount a battery
holder on the back panel.  I used two AA batteries, but anything approximately 3V is OK.  This way, I can easily replace them in the future without
having to disassemble anything.  Plus I can monitor the voltage very easily to see when they need replacement. 

Don't worry about losing calibration values.  You are supposed to run the very easy user calibration procedure periodically anyway.  Download the
service manual from Keysight's web page.

[No.Mad]

Well, I only described how I do it, but it might be a bit of an overkill   
But in my opinion, if you are going to do something, do it by the book / in according to art of electronics.

Anyway, @wn1fju your method is more user friendly in case of hobbyist usage I suppose. But I got myself unit with calibration made in 2014 by Agilent  lab itself, so it would be rather pity to lose calibration, innit?

[Wigo]

 I will meassure the battery voltage ,but i think it os dead already as i get tha low battery warning.

I have to think how i will replace it. I have a few replacent batteries in transit, i found some at farnell, and i have the option to go for the 2032 battery holder or as mentioned above with some other type of battery.

Thanks for the input and answers. I will keep you upt to date.


Edit:
Should this traces be this "thic"? Or is it noise or just false settings?
 

[EHT]

All,

I was wondering the same. I found this post which ends with a question asking for clarification about whether it is necessary to ensure the data is retained either by means of a dump & load or ensuring the memory is powered up all the time. However, no answer...

I also found this thread on the Keysight forum which says:

You are also correct in [saying it is only necessary to] setting the time and date plus the user self cal.

So this person was quite confident that you can replace the battery without retaining any data by any means and then just re-run the User-Cal (an automated procedure as per section 4-7 of the service manual). Can anyone confirm?

BTW I added a second battery + diode in parallel for my 3457A DMM. I was rather hoping this fiddle was not required for the 54622D. I dont have warning message yet.. touch wood!

thanks!

[wn1fju]

I will be the first to say that I could be wrong, but my experience with the similar HP 54610B and HP 54522A scopes is that the user is supposed to
periodically calibrate these things.  So there is no notion of keeping some original, outdated factory calibration, and thus it doesn't require one to
parallel in another voltage source while changing the battery.  And the calibration procedure really is simply to follow the instructions on the screen and
connect the internally generated reference signals.  There are adjustments to the power supply, but the tolerances are pretty wide and I would expect the
voltages to stay in spec for decades.  There is also a CRT adjustment for size, linearity, focus, etc. in case you are truly a perfectionist.

There are plenty of HP/Agilent/Keysight (and others) pieces that do retain calibration constants (for instance, a lot of DMMs), and you would have to
be careful not to lose these unless you had access to a calibration lab.  But IMO, these scopes aren't in that category.

[Wigo]

I found the paragraph in the service manual. In short: you should perform a user calibration every 6 months and a hardware calibration should be done every 12 months.

Funny that you can find no hint, or instructions on replacing the battery in the service manual.

Attached is the page from the service manual.

Btw can someone tell me how i can attach the images within the text? Is there a html command to link the attachment that i am missing?

[Wigo]

So a few days have passed and i got a few parts.

First i replaced the CR2354 - GUN (the soldered battery) with a CR-2354 battery holder. Unfortunatly i have not found one with the right spacing or with three pins so i had to tweak the holder a little bit. But after 10 minutes of de soldering the old dead battery (0,1V) and soldering in the holder and inserting a battery the time of truth has come.
I assambled the scope, reseted it at the startup and after a warm up phase performed a user calibration.
It seems to work fine. Unfortunatly i do not have a suitable frequenzy generator or other pieces of TE to test it in depth.

The next thing i repaired was the broken handle. But this was an easy fix with a little help of 5min epoxy, glaspearls, and a little bit of silikon tape to support the fixed parts.

I will provide pictures once i get the good camera from my wife.

Now all that is left is to give the scope a good cleaning and look out for a battery holder with the right pins and the right spacing of the pins.

Till than,
Happy tinkering