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Products => Test Equipment => Topic started by: gryffinwings on April 18, 2020, 01:03:20 am

Title: Newly acquired HP 3478a! Tips and advice?
Post by: gryffinwings on April 18, 2020, 01:03:20 am
Hi guys, I've finally received my first bench multimeter, an HP 3478a, that I got for a decent price. As far as I know, it currently still functions, and that I need to replace the battery.

Any recommendations on a battery?

Any other recommendations on anything else I need to do maintenance wise?



Sidenote:  Sorry for the orientation of the photos, they weren't originally like that, the forum seems to do weird things, so if anyone knows what's up, then let me know.
Title: Re: Newly acquired HP 3478a! Tips and advice?
Post by: Tj138waterboy on April 18, 2020, 02:29:26 am
I replaced my battery with SAFT LS14250_AX 1/2AA Battery Axial 3.6V 1200mAh from amazon. You will probably find that the mains input rifa caps are cracked so I would probably recommend getting both sets before replacing the battery. There are other post on the forum about what value and size with links to mouser. Biggest concern would be when you remove the old battery if not done properly you will lose calibration data. Again methods of how to do this are on forum and youtube.
Title: Re: Newly acquired HP 3478a! Tips and advice?
Post by: Miti on April 18, 2020, 12:24:44 pm
Here are some useful links related to HP3478A. I would start with saving the calibration constants, then changing the battery.

Adapter:
https://www.eevblog.com/forum/projects/ar488-arduino-based-gpib-adapter/ (https://www.eevblog.com/forum/projects/ar488-arduino-based-gpib-adapter/)

Adapter with bonuses :
https://www.eevblog.com/forum/projects/project-extending-hp3478a-functionality/ (https://www.eevblog.com/forum/projects/project-extending-hp3478a-functionality/)

Free software :
https://www.eevblog.com/forum/testgear/free-hp3478a-multimeter-control-program/ (https://www.eevblog.com/forum/testgear/free-hp3478a-multimeter-control-program/)

You can also use the SW to “tune” the calibration if you need  and you have precision reference gear.

Bonus - backlight :
https://www.eevblog.com/forum/testgear/hp3478a-backlight-my-version/msg1506655/#msg1506655 (https://www.eevblog.com/forum/testgear/hp3478a-backlight-my-version/msg1506655/#msg1506655)

Title: Re: Newly acquired HP 3478a! Tips and advice?
Post by: Gandalf_Sr on April 18, 2020, 12:31:51 pm
Just a tip on the photos, if you're using an iPhone, orient the phone in landscape so the volume buttons are facing the floor and then the raw pictures will be right way up. Or... you can open them in Paint (on a PC), do a mild crop on them, and save them and, again, they will come out the right way up here on EEVBlog.
Title: Re: Newly acquired HP 3478a! Tips and advice?
Post by: GreyWoolfe on April 18, 2020, 01:47:25 pm
Just a tip on the photos, if you're using an iPhone, orient the phone in landscape so the volume buttons are facing the floor and then the raw pictures will be right way up. Or... you can open them in Paint (on a PC), do a mild crop on them, and save them and, again, they will come out the right way up here on EEVBlog.

Irfanview can fix that and resize for the blog and it's free.
Title: Re: Newly acquired HP 3478a! Tips and advice?
Post by: rsjsouza on April 18, 2020, 02:04:43 pm
Just a tip on the photos, if you're using an iPhone, orient the phone in landscape so the volume buttons are facing the floor and then the raw pictures will be right way up. Or... you can open them in Paint (on a PC), do a mild crop on them, and save them and, again, they will come out the right way up here on EEVBlog.

Irfanview can fix that and resize for the blog and it's free.
Funny you say that... I absolutely love Irfanview and, after some time using it for free, I gave money to the developer. Excellent and well supported software - among many features, my favourite one is the JPEG lossless operations (rotate, etc).

This was a hard awakening after I saw Microsoft's Photo Editor (or photo viewer) re-compressing the jpg files after a rotate operation.  :rant:

Oh well... Carry on with the main topic.

I have two 3478As that are quite excellent to use. Sure, they don't have some of the bells and whistles of more modern equipment but are incredibly accurate. The display is a bit of letdown, but you get used to it
Title: Re: Newly acquired HP 3478a! Tips and advice?
Post by: gryffinwings on April 18, 2020, 04:35:57 pm
So here's a photo I took with my DSLR, just trying to provide as much detail as clearly as possible. The Rifa caps, don't look terrible, but I plan on replacing them anyways as this HP 3478a seems to have been manufactured in 1985:

https://www.digikey.ca/product-detail/en/kemet/PME271Y410MR19T0/399-7491-1-ND/3459465 (https://www.digikey.ca/product-detail/en/kemet/PME271Y410MR19T0/399-7491-1-ND/3459465)

https://www.digikey.ca/product-detail/en/kemet/PME271Y522MR30/399-5413-ND/1927358 (https://www.digikey.ca/product-detail/en/kemet/PME271Y522MR30/399-5413-ND/1927358)

These are Y2 rated, the capacitor on the board just has a "Y". Will this capacitor be suitable?

The battery I plan to use is a Panasonic battery, I understand these are pretty good:

https://www.digikey.com/product-detail/en/panasonic-bsg/BR-2-3AE5SPN/P226-ND/61161 (https://www.digikey.com/product-detail/en/panasonic-bsg/BR-2-3AE5SPN/P226-ND/61161)

Title: Re: Newly acquired HP 3478a! Tips and advice?
Post by: rsjsouza on April 18, 2020, 05:02:43 pm
The capacitors look alright. The Y2 rating would be ok as well.

For additional lower cost part numbers, check:
https://www.eevblog.com/forum/repair/hp-3478a-rifa-capacitor-replacement/ (https://www.eevblog.com/forum/repair/hp-3478a-rifa-capacitor-replacement/)
Title: Re: Newly acquired HP 3478a! Tips and advice?
Post by: gryffinwings on April 18, 2020, 05:48:30 pm
The capacitors look alright. The Y2 rating would be ok as well.

For additional lower cost part numbers, check:
https://www.eevblog.com/forum/repair/hp-3478a-rifa-capacitor-replacement/ (https://www.eevblog.com/forum/repair/hp-3478a-rifa-capacitor-replacement/)

I was just looking at those, I have a feeling that the dielectric material of the lower cost caps would actually be more durable, Polypropylene (PP), Metallized than the others which are just Paper, Metallized. The lower cost option also has a higher voltage ratings which I like the idea of.

https://www.digikey.com/product-detail/en/epcos-tdk/B32022A3223M000/495-3794-ND/1648111 (https://www.digikey.com/product-detail/en/epcos-tdk/B32022A3223M000/495-3794-ND/1648111)

https://www.digikey.com/product-detail/en/epcos-tdk/B32021A3102K000/495-4781-ND/3489458 (https://www.digikey.com/product-detail/en/epcos-tdk/B32021A3102K000/495-4781-ND/3489458)