Test Equipment Anonymous (TEA) group therapy thread

[factory]

Check air gap between surge protector and red capacitor near front/rear switch.
High voltage can jump and burn a hole to capacitor.

That is not a capacitor, it's the reed relay I mentioned.

See here...

Ok the blue surge protector are quite close to the switch, not heard about that before, but the red part is still a relay, capacitor is tan colour.

David

[wkb]

The two white cilindrical parts next to the red Coto relay are also surge protectors

[TERRA Operative]

Hi
The  latest addition to my electronic test equipment collection..
An Agilent 33120A 15MHz Function / Arbitrary Waveform Generator.  Probably the youngest member of my  collection.

Never used one before.
Never needed one before.
Never owned one before. 
Now I have one.

Is it practical to DIY retrofit the options and populate the empty BNC ports?

I had a few of these, the 10MHz input does improve the accuracy a lot. I'd definitely look into it.

[factory]

The two white cilindrical parts next to the red Coto relay are also surge protectors

Yes the gas discharge tubes, couldn't remember the full name of these parts earlier. Those were very close to the metal shield of the red reed relay in mine.

I'm sure there was a thread on here (found it, link below), where someone found damage caused by the input arcing to the relay shield, there was a mention the component positions changed slightly in later revisions.

https://www.eevblog.com/forum/testgear/check-your-34401a-multimeter/

David

[m k]

That is not a capacitor, it's the reed relay I mentioned.

Yes, my bad.

Somewhere around here is a picture of the hole.

[FPSychotic]

Well, they still are sold by $500,£400 in ebay.

I got one from Japan in great condition and a keithley in good condition, no as good, but cheaper.
You have a good friend.hehe

[FPSychotic]

Good couple weeks, got R&S FSL18 as new and got all the SW upgrades, x2 EPM-P calibrates meters, E9327A  Peak sensor, 8481h,8482a,2x 8484a with cal attenuator, Tektronix P6150 9Ghz Zo low impedance RF probe, Agilent 34401A,Keithley  2000 ,Calkit HP 85033D, 10 standars Anritsu 26Ghz ,everything like new or new. Ohh, and also a 8684D Generator

[wkb]

That sure is a good score altogether! 

[squadchannel]

I also picked up a 34401A for $20 a few months ago and fixed it up.
I'll post about it soon.

[wkb]

$20.... I hate that 

[m k]

Rip off.

I'm sure there was a thread on here (found it, link below),

I also found it.

[squadchannel]

https://www.eevblog.com/forum/testgear/$20-hp-34401a-repair-log/
 

[Vince]

..
Oh, got extremely lucky for a change, unbelievably lucky.

A friend just sent me a FREE HP 34401A bench DMM !
...

What is the revision(Menu->SYS->Revision)?

It's 03-01-01 , is that bad ?

[Vince]

@Vince, here's where I buy my bumpers and handles, bought a good number over time and always a good product:
https://www.ebay.com/itm/177760378635

Thanks for that  ! Fresh new rubber, at an affordable price at that ! 
Straight from china but if you say they are good quality, I trust you.
Worth a shot at any rate. Sadly the Ebay ad appears to be american, which means importation fees, making it uneconomical.
But since it's from china, hopefully there have ads for these things in the Euro zone as well, will search...

Or if you prefer the older type handle:
https://www.ebay.com/itm/267623997465

If you find anyone selling the older bumpers and handle as a set, let me know.

Well I won't be much help as I am totally clueless when it comes to these instruments : before you mentioned it, I didn't even know there were to models of handles ! 

Also, if you decide to replace the VFD, go buy one of these, they are really good:
https://www.eevblog.com/forum/testgear/hp-agilent-34401a-vfd-to-led-display-conversion/msg6097949/#msg6097949

Oh wow, the guy who sells them was well motivated ! Looks like a polished solution, got a custom display made by a display company, fancy ! 
Too bad he could not reproduce the cyan colour of the VFD display... his is blue and I hate blue with a passion words can't even begin to describe ! 
Looks anachronistic too, in these instruments. However he says his modules can be set to at will to to either blue or white. White might please me.
Still, here again it's a US seller so once imported it's not economical at all.
I still prefer old school VFD displays, I find them sexy like Niksee tubes... but it's good to know there is an option if my VFD degrades and becomes frustrating....
If he could get a display company to make a brand new LED products, wouldn't it be possible to make a brand new... VFD ! Sounds more logical...
Oh, I see in the comments in the EEVblog video the sellers linked to on his website, that there does exist VFD reproductions... but that they are no good sadly   

[m k]

..
Oh, got extremely lucky for a change, unbelievably lucky.

A friend just sent me a FREE HP 34401A bench DMM !
...

What is the revision(Menu->SYS->Revision)?

It's 03-01-01 , is that bad ?

No, just old.

-01 Means it has an old VFD.

https://www.eevblog.com/forum/testgear/agilent-34401a-revisions/

[squadchannel]

You're really lucky to be able to get a 34401A in good condition for free.

[Vince]

The other thing I did was add some insulation, between the reed relay and spark gaps on the front end, they can flash over on the older ones, due to limited the clearance & the reed relay having a painted metal cover.

David

Thanks. I checked the link / topic you posted a bit further down, interesting for sure.
Well I checked my unit and the spark gaps are intact and so is the relay 
I tried to shove a piece of Kapton tape but even that was too thick, there is just zero clearance 
I see on the pictures there, that later designed used spark gaps with a smaller diameter in order to create clearance, saves from an expensive respin of the PCB I guess...

Well not much I can do about it then. Luckily I don't plan on ever measuring THT with this instrument so that's OK. I will keep this limitation in mind.
For HV / CRT stuff I have my HV probe, helps.

[Vince]

You're really lucky to be able to get a 34401A in good condition for free.

Yeah I still can't believe it myself, good luck indeed.
To bring some context to this instrument, the friend who gave it to me actually just got it for free himself (he passed it on to me) from an old HAM in Paris who himself got it from an auction / lot of TE that some lab / company disposed of. That guy actually (nor my friend) never ever even powered up this meter. It basically came to me in 100% unknown condition. Of course since it was free it was worth it ! It's just pot luck that it turned out to be a good unit ! 

[factory]

Also, if you decide to replace the VFD, go buy one of these, they are really good:
https://www.eevblog.com/forum/testgear/hp-agilent-34401a-vfd-to-led-display-conversion/msg6097949/#msg6097949

Oh wow, the guy who sells them was well motivated ! Looks like a polished solution, got a custom display made by a display company, fancy ! 
Too bad he could not reproduce the cyan colour of the VFD display... his is blue and I hate blue with a passion words can't even begin to describe ! 
Looks anachronistic too, in these instruments. However he says his modules can be set to at will to to either blue or white. White might please me.
Still, here again it's a US seller so once imported it's not economical at all.
I still prefer old school VFD displays, I find them sexy like Niksee tubes... but it's good to know there is an option if my VFD degrades and becomes frustrating....
If he could get a display company to make a brand new LED products, wouldn't it be possible to make a brand new... VFD ! Sounds more logical...
Oh, I see in the comments in the EEVblog video the sellers linked to on his website, that there does exist VFD reproductions... but that they are no good sadly   

I absolutely hate blue LEDs and over bright LEDs of any color myself, if I was unhappy with either of my 34401A (which I'm not) I would stay with the VFD replacements.

Those LED replacements seem to be cyan for the starburst segments & white for the annunciators.
I'm sure cyan & white are only available as blue LEDs with a phosphor layer for the color, these will degrade over time. And from experience with 1980s & 90s equipment (from trains) that was powered continuously, single color LEDs also degrade with time.

Of course none of this probably matters, as neither of us are likely to leave our 34401As running 24/7 and for the one thing here that is running 24/7 with a VFD, the segments that are used all the time (for the time & channel number) were only noticeably dimmer after 10+ years.

As for comments about the clone VFD being no good, I would rather see some unbiased opinions from elsewhere, not from a video advertising LED versions.

Edit, for those that might prefer a TFT display replacement, Ian Scott Johnson has a project here;
https://www.ianjohnston.com/index.php/conversions/video-blog-181-34401a

David

[TERRA Operative]

Here's a direct comparison using the VFD LED replacement on my 53132A, comparing the LED against a brand new VFD. It doesn't have white, but it is the newer cyan colour instead of the intense blue of the first revision.

[Zoli]

It's 03-01-01 , is that bad ?

No, as long the display is OK; I would say it has well aged reference.

[Hydron]

You do miss the chance to enable some hidden features they added later (iirc FW 7 and up). Not a big worry for a free unit though!

[dazz1]

Hi
The  latest addition to my electronic test equipment collection..
An Agilent 33120A 15MHz Function / Arbitrary Waveform Generator.  Probably the youngest member of my  collection.

Never used one before.
Never needed one before.
Never owned one before. 
Now I have one.

Is it practical to DIY retrofit the options and populate the empty BNC ports?

I had a few of these, the 10MHz input does improve the accuracy a lot. I'd definitely look into it.

Yeah I'd then have justification for getting a 10MHz frequency standard.   
I found some new old kits on ebay.  Quite spendy though.  More than I paid for the AWG.

[flash2b]

Get this one: https://www.eevblog.com/forum/testgear/10mhz-gpsdo-by-bh3sap/msg5598659/#msg5598659

And update the firmware to enable all the additions that have been made to this unit !

[factory]

Here's a direct comparison using the VFD LED replacement on my 53132A, comparing the LED against a brand new VFD. It doesn't have white, but it is the newer cyan colour instead of the intense blue of the first revision.

I still prefer the colour of the original one.
At least it's different enough for me to avoid buying any units that have this replacement, not that I actually want any counters from this range.

David