HP 3478A $40 BIN USA

[GregDunn]

If you're interested in selling any of the repaired meters.....   

[TERRA Operative]

A bit of a long shot maybe, but I have one of these meters I am repairing.
It all works and passes checks, but the AC current and AC voltage functions don't work.
I've traced it to a faulty 1QF7-0067 (U102), so I am trying to track one down.

Does anyone have one of these parts, working or not, that they are willing to sell?

[BradC]

A bit of a long shot maybe, but I have one of these meters I am repairing.
It all works and passes checks, but the AC current and AC voltage functions don't work.
I've traced it to a faulty 1QF7-0067 (U102), so I am trying to track one down.

Does anyone have one of these parts, working or not, that they are willing to sell?

They are as rare as rocking horse shit. I wonder if the same/similar hybrid from the 3457a would work? I've never looked at them that closely, but they are available. I always thought they were identical, but just noted they are different part numbers. Might have to look at the schematics to see if I can pick the difference.

[TERRA Operative]

Yeah, I would even take one from an otherwise dead unit.

I want to strip it down to see if it could be reverse engineered with common parts, but I don't want to potentially sacrifice my otherwise good meter (besideds the AC ranges).

Would be cool to be able to build a replacement addin board from discreet components.

[GreyWoolfe]

I took a couple of pictures of the PCB since I was replacing the RIFA and electrolytics and the battery.  Here is the top and bottom.  You can see how clean it is.  I didn't clean the PCB before I started.  You can also see how bad the RIFA caps are.  I did the electrolytics as I was replacing the RIFA caps anyway and they were the original electrolytics.  They were replaced with proper Nichicon capacitors.  Now, I am waiting for the power buttons from bratster and then it will go to ordinaryman for a basic calibration.  For the record, I used my isolation transformer with my soldering station so as not to short anything out.  The bezel and case cleaned up very well with some simple green

Total cost to date (rounded to nearest dollar):
meter and shipping-----$58
parts and shipping------$27
buttons and shipping---$15
Total so far--------------$100

If I can get away with under $40 shipping both ways to ordinaryman, that would make the total investment in a calibrated meter with new caps and battery for about $140 USD.  I think I have done OK.  They are going on evilBay right now for $100 BIN and up uncalibrated and unknown battery/cap condition.  The 2 listed with calibration are $325 and up.  I will be very happy at the end of the process.  The next pics I post will be the buttons that I receive from bratster.

[bitseeker]

It is nice and clean inside. Glad to hear all went well with the battery change. Those RIFA caps are quite cracked — disasters waiting to happen.

I didn't pay attention earlier, but seeing inside I noticed you have the earlier revision that uses toroid transformers for communicating between the analog and digital sides instead of opto-isolators. I like the enclosures that HP used for those 3478A as they have more metal, less plastic.

In fact, a dead 3478A of similar vintage is on its way to me. Will it be a cinch or a disaster? Only time will tell.

[GreyWoolfe]

Thanks to the Blog and all the horror stories I have read about exploding RIFA caps, that was the first thing I looked for when I opened it up.  Then I measured the battery and it read 70 mV--I think it might have been dead.  I changed the electrolytics as the board looks like it never had any rework outside of a possible battery change in the past.  There was a little flux residue near one of the pins.  Hopefully, the meter will stay happy for years and I hope yours turns out to be as easy as mine has been so far.

[bitseeker]

Yep, will let you know when I get it. Looking forward to seeing your final wrap up after calibration.

[Bratster]

I took a couple of pictures of the PCB since I was replacing the RIFA and electrolytics and the battery.  Here is the top and bottom.  You can see how clean it is.  I didn't clean the PCB before I started.  You can also see how bad the RIFA caps are.  I did the electrolytics as I was replacing the RIFA caps anyway and they were the original electrolytics.  They were replaced with proper Nichicon capacitors.  Now, I am waiting for the power buttons from bratster and then it will go to ordinaryman for a basic calibration.  For the record, I used my isolation transformer with my soldering station so as not to short anything out.  The bezel and case cleaned up very well with some simple green

Total cost to date (rounded to nearest dollar):
meter and shipping-----$58
parts and shipping------$27
buttons and shipping---$15
Total so far--------------$100

If I can get away with under $40 shipping both ways to ordinaryman, that would make the total investment in a calibrated meter with new caps and battery for about $140 USD.  I think I have done OK.  They are going on evilBay right now for $100 BIN and up uncalibrated and unknown battery/cap condition.  The 2 listed with calibration are $325 and up.  I will be very happy at the end of the process.  The next pics I post will be the buttons that I receive from bratster.

Would you mind sharing the part numbers for the replacement capacitors you used?


Sent from my Fi Moto x4 using Tapatalk

[GreyWoolfe]

Would you mind sharing the part numbers for the replacement capacitors you used?
Sent from my Fi Moto x4 using Tapatalk
[/quote]

Bratster, I assume you mean the RIFA caps.  Here are the part numbers:

.022 uF Digi-key part number 399-5413-ND, manufacturer part number PME271Y522MR30
1000 pF Digi-Key part number 399-5409-ND, manufacturer part number PME271Y410MR30
                                                399-7491-1-ND                                                PME271Y410MR19T0

EDIT, Sorry Bratster, I was trying to go from memory.  I found my invoice and have corrected the part numbers for the 1000 pF RIFA cap

[GeorgeOfTheJungle]

but I have lived in Hollywood Beach and Hallandale Beach.

Hallandale! I''ve been there, summer 1979, Motel Sun Aqua :-)

[GreyWoolfe]

but I have lived in Hollywood Beach and Hallandale Beach.

Hallandale! I''ve been there, summer 1979, Motel Sun Aqua :-)

I lived there in the mid 90's.  The apartment wasn't that far from the beach.  Nice little beach with a boardwalk.

[chekhov]

Two more units: https://www.ebay.com/itm/292757399598?, with button  !!!
Well, probably rather good opportunity, especially when don't need to pay x3 price for delivery.

[Mr. Scram]

Two more units: https://www.ebay.com/itm/292757399598?, with button  !!!
Well, probably rather good opportunity, especially when don't need to pay x3 price for delivery.

The nerve of some people. "Good cosmetic condition"  It's hardly the worst I've ever seen, but it's certainly well used.

[PlainName]

Considering the competition going for more and in considerably worse condition, it is actually quite good!

This is what you call cosmetically challenged

[Mr. Scram]

Considering the competition going for more and in considerably worse condition, it is actually quite good!

This is what you call cosmetically challenged

The fact that a turd tastes worse than your cooking doesn't make the latter haute cuisine.

[chekhov]

Neither two of meters above are in really bad conditions from the outside (compare to this https://www.ebay.com/itm/222396890942?). And, what to expect from 29-30 year old gear ?
It goes without saying that you have to disassemble it and wash, at least front panel, buttons - only after that I will feel comfortable to work with such instrument.
The more important are possible scratches (which may mean physical damage) and internals - here is where dust it less wanted.

[GreyWoolfe]

This will probably be the last post.  I received the buttons from Bratster.  Brett, thank you very much.  The buttons look great and are a nice tight fit on the shafts.  I also added a couple of pics of the feet I used.  I have a small quantity of these and they set the meter at a nice height.  More importantly, they were free!!  Now I need to see what I can get rid of to pay for the calibration.

[bitseeker]

That worked out nicely, GW.

[GreyWoolfe]

Considering the competition going for more and in considerably worse condition, it is actually quite good!

This is what you call cosmetically challenged

Believe it or not, I was half tempted just to have the old style label maker sticker that says Electronic Warefare.

That worked out nicely, GW.

Very happy to have no borked power button.

[GreyWoolfe]

UPDATE:  I just got a PM from Ordinaryman1971.  The calibration is done and the meter is on its way back to me.  I can't thank him enough for his kindness.  It took awhile because he's been very busy but I am grateful for his help.  Thanks, again, OM.

[xrunner]

Great!

[bitseeker]

That's great news GW. I bet you can't wait to measure something.

[Haasje93]

Not affiliate with the seller. It seems like it is worth looking at.

 https://www.ebay.com/itm/Lot-Of-2-Hewlett-Packard-3478A-Digital-Multimeter/362481326514?hash=item54659219b2:g:B8UAAOSwS4Vb42mt:rk:1:pf:0

[Ordinaryman1971]

By the way... if anybody needs 5 or 6 digit meter calibrated I'm more than happy to help. I have all the gear... just little time.
So, if you are in a pinch give me a pm and I can do it for you. It's completely free to all eevblog members, you just have to pay for the shipping to Chicago and back. Or if you close-by you can always drop it off.
I also have some parts for those meters, I can print buttons too, lol. Color of your choice... I have black and also... black and if you really insist I have black as well.