EEVblog Electronics Community Forum
Products => Test Equipment => Topic started by: Homer J Simpson on January 18, 2013, 01:11:07 am
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Well I just won the auction on the 3478A.
Looks clean. If it is as accurate at the other ranges as it is pictured on the volts range I will be happy.
I have wanted to get one of these for a while. I have a Fluke 8840A now. This should compliment it well.
I ended up getting it for $150 shipped.
Any tips or advice from any one who already has this meter?
Will post again once I receive and check out.
KT
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Check the date code and voltage of the backup lithium battery.
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Is that a standard 2/3 A 3v lithium battery?
Thanks
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Is that a standard 2/3 A 3v lithium battery?
Thanks
http://www.ebay.co.uk/itm/1420-0278-Agilent-HP-Lithium-Battery-3V-95A-for-3478A-/350546682442?pt=LH_DefaultDomain_0&hash=item519e35e24a (http://www.ebay.co.uk/itm/1420-0278-Agilent-HP-Lithium-Battery-3V-95A-for-3478A-/350546682442?pt=LH_DefaultDomain_0&hash=item519e35e24a)
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Is that a standard 2/3 A 3v lithium battery?
Thanks
http://www.ebay.co.uk/itm/1420-0278-Agilent-HP-Lithium-Battery-3V-95A-for-3478A-/350546682442?pt=LH_DefaultDomain_0&hash=item519e35e24a (http://www.ebay.co.uk/itm/1420-0278-Agilent-HP-Lithium-Battery-3V-95A-for-3478A-/350546682442?pt=LH_DefaultDomain_0&hash=item519e35e24a)
And it's a used one...
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20$ for that cell ? Bloody hell ! Thats a 3$ part... Need one ?
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I wonder if the CR123A cell is the same size as the backup battery? I wonder if its possible to buy a battery holder and solder it into the existing footprint to allow easy replacement of the battery.
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CR123A cells have a slightly larger diameter, but you should be able to make it fit. If not using a battery holder, you want one with solder wires/tabs, unless you have access to spot welding equipment. A battery holder should work, as long as you can make it fit. The reliability when exposed to vibration will be worse, which is most likely why HP opted for soldering. It's not like you have to change it every few months.
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That is what I had thought.
A standard CR123A 2/3 a 3v lithium will work ok.
I might do the setup with the battery holder.
Will have the meter next week and will take a look.
Has any one done the battery swap with the CR123A?
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Found this.
Battery Holder Case Box For CR123
http://www.ebay.com/itm/Battery-Holder-Case-Box-For-CR123-CR123A-Photo-Lithium-Battery-/150849186477?pt=US_Battery_Converters&hash=item231f4feaad (http://www.ebay.com/itm/Battery-Holder-Case-Box-For-CR123-CR123A-Photo-Lithium-Battery-/150849186477?pt=US_Battery_Converters&hash=item231f4feaad)
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I used this a few years ago, they stock fresh cells
http://shopping.microbattery.com/Panasonic-BR2-3AE-2SP-Lithium-with-PINS-3V-1200-mAh (http://shopping.microbattery.com/Panasonic-BR2-3AE-2SP-Lithium-with-PINS-3V-1200-mAh)
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I considered doing the holder swap on my 3478A, but it seems like the battery has been changed somewhat recently and the battery reads over 3.2 Volts
Regarding vibration resistance, its probably possible to loop a zip tie underneath the battery holder to keep the cell in place
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I received today and have started to check it out.
I have downloaded the user manual but wanted to ask a quick question for the group. Are sure many of you have this meter.
On my fluke 8840 I can short the test leads and press the "offset" button and it will zero out the resistance of the test leads.
Does this 3478 have the same function? At first glace I am not seeing it.
Thanks
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Be sure to keep the unit powered on (or at least keep the 3V voltage via a secondary battery) when changing the onboard battery. Otherwise the calibration information stored in RAM will be lost! Some people claim that if you swap out the battery really quickly you are OK, but I'd rather be safe then sorry...
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No offset/null feature as far as I'm aware. An odd omission, since competing models did offer it.
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Be sure to keep the unit powered on (or at least keep the 3V voltage via a secondary battery) when changing the onboard battery. Otherwise the calibration information stored in RAM will be lost! Some people claim that if you swap out the battery really quickly you are OK, but I'd rather be safe then sorry...
What if the soldering iron is connected to the ground? Wound't that cause any problem when soldering on a live circuit? (I am sure this is a stupid question for most of you, sorry).
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Be sure to keep the unit powered on (or at least keep the 3V voltage via a secondary battery) when changing the onboard battery. Otherwise the calibration information stored in RAM will be lost! Some people claim that if you swap out the battery really quickly you are OK, but I'd rather be safe then sorry...
What if the soldering iron is connected to the ground? Wound't that cause any problem when soldering on a live circuit? (I am sure this is a stupid question for most of you, sorry).
Well, if the tip is grounded, you will can do it one of many ways:
1. unplug the iron when soldering the positive side. or
2. use a butane soldering iron
3. use the back up battery method (hook up one in parallel temporarily)
If you are unsure, I would recommend using the last approach as it is safer when the rest of the circuit is powered off. When soldering a live circuit, you need to have very steady hand and don't want to accidentally short out anything.
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Well I have been doing some quick checks this evening on this meter.
When I bought my 8840 it was sold as calibrated. I thought it was pretty close but I don't have a voltage standard yet to check.
I guess the 8840 was calibrated after all.
I do miss the offset feature on the HP though.
Resistance measurement are on also but on the HP you have to read the resistance of the leads first then subtract them from your measurement.
I like the HP and it is nice to have 2 meters to check accuracy but if I could only have one I would go with the Fluke. IMO
KT
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Be sure to keep the unit powered on (or at least keep the 3V voltage via a secondary battery) when changing the onboard battery. Otherwise the calibration information stored in RAM will be lost! Some people claim that if you swap out the battery really quickly you are OK, but I'd rather be safe then sorry...
What if the soldering iron is connected to the ground? Wound't that cause any problem when soldering on a live circuit? (I am sure this is a stupid question for most of you, sorry).
Well, if the tip is grounded, you will can do it one of many ways:
1. unplug the iron when soldering the positive side. or
2. use a butane soldering iron
3. use the back up battery method (hook up one in parallel temporarily)
If you are unsure, I would recommend using the last approach as it is safer when the rest of the circuit is powered off. When soldering a live circuit, you need to have very steady hand and don't want to accidentally short out anything.
Ok thanks. The option 1 seems difficult as the iron temperature would drop as soon as you unplug the iron. Or use an isolation transformer to power the iron?
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Put the isolation transformer on the meter instead, it uses less power.
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Put the isolation transformer on the meter instead, it uses less power.
Yep, also some soldering stations will not work if they don't have proper connection to ground.
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Resistance measurement are on also but on the HP you have to read the resistance of the leads first then subtract them from your measurement.
You can also use 4-wire resistance measurement to compensate for lead resistance.
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What reading do you get when you short out the leads on AC current or AC volts on your 3478A? Mine reads at 0.480mV AC and 0.6802mA AC. I'm not quite sure if thats normal for this meter because the service manual does not appear to list this spec for AC current or Volts
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What reading do you get when you short out the leads on AC current or AC volts on your 3478A?...
I have two units. With shorting plug: first unit 0.433mVac and 0.565mAac, second unit 0.473mVac and 0.592mAac. Neither one really ever settled on one value, they were bobbling up and down a couple of counts.
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True RMS meters rarely read zero when shorted. See for example this Keithley document (http://www.keithley.com/support/data?asset=11635). The True RMS converter is non-linear near zero, so accuracy at larger inputs would be compromised if it was calibrated to read 0 with its inputs shorted. True RMS meters are usually specified from 5% or so of full scale in AC ranges. At these values the contribution of the offset is negligible, as the Keithley document shows.
The accuracy specs are listed in the manual. Its allowed about 1% + 163 counts in AC current mode for sinusoidal inputs at least 10% of full scale, so when applying a 30 mA 1 kHz input, it should read between 29.621 mA and 30.379 mA. Anything below 10% of full scale is unspecified, so a 30 A reading with shorted inputs would be in spec.
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What's the best way to replace the battery in the 3478A? The service manual doesn't seem to go in much detail. The battery in my unit reads 3.054V but I would like to replace it as I do not know it's age and it looks original.
Would it be OK to hook up a bench power supply set to 3.0Vdc in parallel while removing the old battery? I have a Weller Pyropen so the grounded tip is not an issue for me.
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I would just leave the unit powered on, that will keep power to the memory. Just be careful of the high voltage area, put some tape over where the IEC plug is soldered to the PCB
To make desoldering easier, break the spots welds on the battery and remove it. Then you have less of a thermal mass to heat up and you can remove the pins by heating up the joint and removing it with a pair of pliers.
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While this thread is old... it deserves a warning... The - pole of the battery IS connected to AC ground. IF you use a grounded soldering iron on the plus pole, you just shorted out the battery backup and lost the cal constants!
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So, should I get a 3478 or a 8840. Both are around the same, generally affordable price point...
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AC measurements and GPIB are optional on the 8840A. If you want them be sure the options are installed. Check that the VFD is not worn out.
I have a 8840A but not a 3478A. I see following advantages of the 8840A:
VFD vs. LCD
Can take shrouded banana plugs
Has a offset (null/delta) function
High impedance input up to 20V vs. 3V
1000V vs. 300V max voltage range
Calibration data in EEPROM (no battery)
Advantages for the 3478A:
303100 counts vs. 200000
lower rages: 30mV, 30 ohm, 300mA
Read the manuals from both and decide yourself.
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Well I just won the auction on the 3478A.
Looks clean. If it is as accurate at the other ranges as it is pictured on the volts range I will be happy.
I have wanted to get one of these for a while. I have a Fluke 8840A now. This should compliment it well.
I ended up getting it for $150 shipped.
Any tips or advice from any one who already has this meter?
Will post again once I receive and check out.
KT
If you scrap it I will buy the front plate, mine arrived with a cracked front plate due to shipping/packing :-DD
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Sorry for digging up this ancient thread... I have just acquired one myself, however, I would like to perform a battery swap when I receive it. Since I have a floating power supply, couldn't I just parallel that and use my soldering iron to swap out the battery?
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Sorry for digging up this ancient thread... I have just acquired one myself, however, I would like to perform a battery swap when I receive it. Since I have a floating power supply, couldn't I just parallel that and use my soldering iron to swap out the battery?
https://www.eevblog.com/forum/beginners/changing-battery-in-a-hp-3478a-can-i-use-a-3v-lithium/ (https://www.eevblog.com/forum/beginners/changing-battery-in-a-hp-3478a-can-i-use-a-3v-lithium/)
/Bingo