HP 3478A $40 BIN USA

[Ordinaryman1971]

Correct, you may end up with a "free" meter if they decide not to get it returned. I can calibrate it for you, the problem is that you would have to ship it to Chicago... or just use it uncalibrated. The message disappears after few seconds and the meter should be fine, even without the calibration present.

[GreyWoolfe]

As a sometimes buyer of very inexpensive ebay deals I have a question. After putting in the battery, would you be likely to know if there are any other faults that would make calibration impossible without repair? If you send it off to the cal lab and they tell you this is the case after getting into it, are you still liable for the $75 fee? I am curious if this is a situation where you just keep getting in deeper dollar wise and still wind up without a working meter. Thanks, your neighbor to the south

I don't know as I have never had anything calibrated before.  The meter works, it's just off.  The uncalibrated message seems to mean a dead battery as the general consensus suggests.  The battery is cheap, under $6.  Not that I ever do anything needing a NIST calibrated meter but it would be cool to have.  I have decided to suck it up, keep the meter, replace the battery and work on the cash for the calibration.  Time to see what I can get rid of.

[GreyWoolfe]

Correct, you may end up with a "free" meter if they decide not to get it returned. I can calibrate it for you, the problem is that you would have to ship it to Chicago... or just use it uncalibrated. The message disappears after few seconds and the meter should be fine, even without the calibration present.

PM sent.

[GreyWoolfe]

I opened the meter to take a peek inside and found 4 RIFA capacitors, 2 .022uF Y and 2, 1000 pF Y caps.  The housings all have cracks running through them so I need to replace them when I replace the battery.  If I am reading correctly, these are metalized film capacitors.  Would this from KEMET as an example, be a good substitution?

https://www.digikey.com/product-detail/en/kemet/R76PI22204030J/399-12594-ND/5731085

If not, what would I want to buy?

I also plan to replace the 5 electrolytic caps.  They appear to be original and the PCB is dated 9th month 1985

[bitseeker]

If those RIFA caps go across the mains (I don't recall which do in that meter), then that KEMET series is not rated for that purpose. Check the datasheets. Also, I recall seeing these replacements being discussed on the forum before. A search may get you some component recommendations.

[GreyWoolfe]

If those RIFA caps go across the mains (I don't recall which do in that meter), then that KEMET series is not rated for that purpose. Check the datasheets. Also, I recall seeing these replacements being discussed on the forum before. A search may get you some component recommendations.

I did a bit more digging and have the proper replacements, the battery and electros coming from Digi-key.  After that, calibration.  Now to find a replacement power button.  So far, the part number doesn't turn up anything.  I will keep practicing my GoogleFu.

[bitseeker]

I recall some putty-like stuff that hardens after molding and can be sanded, painted, etc. Unfortunately, I don't remember what it's called. It could be a quick fix to add the missing tip to the power switch arm.

[GreyWoolfe]

I recall some putty-like stuff that hardens after molding and can be sanded, painted, etc. Unfortunately, I don't remember what it's called. It could be a quick fix to add the missing tip to the power switch arm.

Many years ago when I was into military modeling, I used a product called squadron green putty to add dirt and mud build up around and under tank bogeys and fenders.  That stuff dried hard.  I will have to see if it is still available.  Maybe someone else could chime in on a usable product.

[Old Printer]

At work (a sign shop) we use 2 part epoxy putty J-B Weld called SteelStick. It's good stuff, about six bucks at Depot. So much for your $40 meter huh?    Been there enough myself, just the way it goes sometimes.

[GreyWoolfe]

At work (a sign shop) we use 2 part epoxy putty J-B Weld called SteelStick. It's good stuff, about six bucks at Depot. So much for your $40 meter huh?    Been there enough myself, just the way it goes sometimes.

No kidding.  $40 plus the shipping.  $25 for the battery and replacement caps with shipping.  A few bucks for some sort of solution for the button, though I can still power it up the way it is.  I am also thinking Delrin/plastic bar stock from the local hobby shop shaped and epoxyed onto the end might be a solution.  Then the shipping both ways to ordinaryman for the calibration.  Still a steal.

[Bratster]

For the button, a member on here designed a 3D model that I have printed and works great to replace the power and input buttons on mine.

I will go find that post/thread and Link it back here in a moment.



Sent from my Fi Moto x4 using Tapatalk

[bitseeker]

Thanks, Bratster. Thingiverse has some test equipment parts, but not for this meter the last time I checked. Looking forward to seeing the one you tried.

[Bratster]

Here is the thread.

https://www.eevblog.com/forum/repair/where-to-find-a-new-power-switch-for-a-hp3478a/

Sent from my Fi Moto x4 using Tapatalk

[GreyWoolfe]

For the button, a member on here designed a 3D model that I have printed and works great to replace the power and input buttons on mine.

I will go find that post/thread and Link it back here in a moment.



Sent from my Fi Moto x4 using Tapatalk

Thanks for posting the the link.  I don't have a 3D printer.  Would you possibly be able to print a couple and I would happily relinquish coin of the realm for time/materials and postage?

[Bratster]

For the button, a member on here designed a 3D model that I have printed and works great to replace the power and input buttons on mine.

I will go find that post/thread and Link it back here in a moment.



Sent from my Fi Moto x4 using Tapatalk

Thanks for posting the the link.  I don't have a 3D printer.  Would you possibly be able to print a couple and I would happily relinquish coin of the realm for time/materials and postage?

You would get a higher quality part if you order it through shapeways or one of those other 3D printing services.

The member that designed it did mention in that other thread that he was going to adjust the model slightly since I had to modify the physical print to make it fit.

 You may want to ask them if they can print it for you.



If you don't want to go that route I would be open to printing some, just PM me your ZIP code so I can figure out what shipping would be.



Sent from my Fi Moto x4 using Tapatalk

[SeanB]

Otherwise Sugru is the stuff you are thinking of, though I would typically just use a big blob of 2 pack Pratley putty, and mix it together, mould roughly to shape, press onto the shaft to get the interior shape correct after making a rough large outer, then finish it off after 24 hours when it has cured, and then finally when finished cure at 60C for a day to get fully hard, and then spray it appropriately.

[GreyWoolfe]

For the button, a member on here designed a 3D model that I have printed and works great to replace the power and input buttons on mine.

I will go find that post/thread and Link it back here in a moment.



Sent from my Fi Moto x4 using Tapatalk

Thanks for posting the the link.  I don't have a 3D printer.  Would you possibly be able to print a couple and I would happily relinquish coin of the realm for time/materials and postage?

You would get a higher quality part if you order it through shapeways or one of those other 3D printing services.

The member that designed it did mention in that other thread that he was going to adjust the model slightly since I had to modify the physical print to make it fit.

 You may want to ask them if they can print it for you.



If you don't want to go that route I would be open to printing some, just PM me your ZIP code so I can figure out what shipping would be.



Sent from my Fi Moto x4 using Tapatalk

I sent an email to shapeways and see where that goes.  I will also PM my zip code.

[bitseeker]

Yeah, I think Sugru was it. Thanks, Sean.

[coromonadalix]

I know its a long shot, but you could / can find old defective hp mainframes modules who could give you the switchs knobs needed in the future ??

[PaulAm]

They always seem to be missing the button you need.  Power buttons seem to be a particular favorite to go missing.  I have a couple pieces waiting for a new power button.

I've used 2 part auto body filler to make up stuff on occasion.  In the US there's a product called Duraglass which is epoxy filler with fiberglass, although I'm sure similar products are available elsewhere.  It's waterproof, durable and does not crack.  Once it gets partially set you can sculpt it with a sharp knife (if you're fast).

You could also make a mold of a different button and use liquid fiberglass resin to mold one.

Lately, I'm leaning toward the 3d printer route.

[xrunner]

I sent an email to shapeways and see where that goes.  I will also PM my zip code.

Here it is -

https://www.ebay.com/i/183300958427?chn=ps

 

[GreyWoolfe]

I sent an email to shapeways and see where that goes.  I will also PM my zip code.

Here it is -

https://www.ebay.com/i/183300958427?chn=ps

 

You da MAN, X!!

[xrunner]

You da MAN, X!!

I try, I try. 

[bitseeker]

Amazing! I wasn't expecting that.

[ArthurDent]

Several weeks ago I was looking through the electronics for sale section on CraigsList and found someone who was selling a lot of used test equipment, every piece with some problem. Along with many other pieces of test equipment I ended up with about seven HP3478A, one with a very defective display that became a parts donor for the rest. Two or three had dead batteries and gave the ‘uncalibrated’ message on power up, and a couple of missing or blown input fuses, a broken power switch, and a missing power button cap. There was one that had been dropped and although there wasn’t any physical damage the connector between the main board and the front panel was broken and that took some time to repair. 

I have some stable power supplies and resistance standards and I also have an HP 3457A 6.5 digit meter that I have great confidence in. After I repaired the problem(s) with each meter I could use my voltage standard (EDC 330, 7 digits) to set zero and all the multiples of 3 for each D.C. voltage calibration point. If there was any small disagreement between the EDC reference and the HP 3457A, I adjusted the reference to agree with the HP 3457A, and that was the method I relied on to set the calibration points on all the HP 3478A meters. I followed the same procedure for resistance using an ESI 6 decade box and a couple of very high value resistors to calibrate all the resistance ranges, always using the HP 3457A as the final word. I used the same procedure for A.C. and D.C. amps. After running through all the calibration steps I could exit the calibration mode and every repaired meter passed self test and worked properly. Checks at random points of other references and standard resistors indicated that the meters were within specs. Although it isn't exactly a true calibration I am quite confident in the results. 

I was pretty please that I got all but one of them working and that they were within driving distance, and they were only $20 each.