Fair price for a 34401a with non-working ACV and ACI measurements - Page 1
Forum section: electronics / testgear

author: dsharp02
author_rank: Contributor
timestamp: March 04, 2016, 03:52:54 am
content: I'm a newbie just getting into learning electronics. My day job is software development, but I got bit by the 3D printing bug, and now I'm wanting to learn to make my own circuit boards.Anyhow, I recently purchased a 34401a from eBay that was advertised to be fully functional. After testing with my DMMCheck, everything seems to work except AC volts, and AC current. The 5v AC from the DMMCheck reads as >5.21v. AC current reads as approx 15uA before connecting the 1ma source of the DMMCheck. Connecting the DMMCheck drops the reading to 1-3uA. I contacted the seller for an exchange with a fully functional unit or partial refund ( I really do like the meter). They don't have another unit to exchange, so what would be a fair price for the meter? I paid $390 for the meter. Would $300 ($90 partial refund) be fair? Should I ask for a bigger discount? I don't want to rip the seller off, but I don't want to feel like I got ripped off either. Could this just be a calibration issue?ThanksDave

author: Performa01
author_rank: Super Contributor
timestamp: March 04, 2016, 09:39:10 am
content: From what you tell, it might just be a calibration issue on ACV, albeit a major one. ACI doesn't seem to work at all.All in all, it looks more like a serious problem with the rms converter.You'd need to do some more testing with different voltages/currents, but even without that, I'd say the meter is unusable for AC and this is not just a problem with the calibration.Regarding the price reduction, it is quite simple. How much need do you have for the AC measurements? There have been other meters from Keithley and Fluke, where AC measurements were optional, consequently there are quite some units out there without ACV/ACI, as many tasks don't require it.If you don't need AC measurements, then you can keep the meter for $90 refund, that sounds reasonable.If you do need it, then return the meter and get a fully functional one instead from elsewhere.All that said, I'd have an uneasy feeling with a meter that's only partially working. Since you don't seem to have the means to thoroughly test the unit, who guarantees you that the other ranges are actually working like they should? Obvious problems like you've encountered already would make me rather suspicious...

author: HighVoltage
author_rank: Super Contributor
timestamp: March 04, 2016, 09:48:54 am
content: I have bought many of these 34401A meters also in broken state.https://www.eevblog.com/forum/repair/agilent-34410a-repair-attempt-of-2-dead-meters/msg874162/#msg874162As soon as something is wrong, the price drops by at least 1/2A fully working unit goes for about $ 400 these days or more, depending on the condition.A broken unit is usually below $ 200

author: hendorog
author_rank: Super Contributor
timestamp: March 04, 2016, 09:58:51 am
content: Quote from: HighVoltage on March 04, 2016, 09:48:54 amJust a general comment that those amounts don't consider the fact that 34401a's have been in production a very long time and there are different hardware revisions which vary in repairability. e.g. I got a really old one for $70 and an old one for $200 (within the last few months).I agree with 1/2 price as my uneducated guess is that it is more serious than just calibration. Could you attempt to calibrate it to confirm that - given you have a DMMCheck?

author: Dr. Frank
author_rank: Super Contributor
timestamp: March 04, 2016, 11:04:13 am
content: Quote from: dsharp02 on March 04, 2016, 03:52:54 amI assume, you have a DMMCheck Plus? The simple DMMCheck has no ACV and ACI output.Then, did you apply the 5VAC correctly, which ACV range, are you using, and is your DMMCheck PLUS ok?(These questions may sound silly, but I would trust the 34401A more, than this circuit)For ACI, do you use the 1A AC range?Then 1mA is much too low, the instrument will not display anything below about 1/100 of range!It is not specified for readings < 1/100 of range in ACI, and will even clip to exactly zero below about 1/250 of range!The 34401A can be configured over the bus to have an additional 10mA AC range, which is normally hidden, see application note on the net.Please check, if this has been done by the previous owner. For sure you can activate on your own, as your are a SW guy!So at the moment, I have to assume that your instrument is working correctly.FrankPS: The command is: DIAG:POKE 25,0,1http://www.keysight.com/main/editorial.jspx?cc=DE&lc=ger&ckey=1000001267:epsg:faq&nid=-536902435.536880933&id=1000001267:epsg:faq

author: dsharp02
author_rank: Contributor
timestamp: March 04, 2016, 07:16:13 pm
content: Hi. Thanks for your suggestions. I rechecked my dmm check with my handheld and I get the readings I expect. The AC current testing I did on the 34401a was done on the 10mA range.

author: markone
author_rank: Frequent Contributor
timestamp: March 04, 2016, 09:03:33 pm
content: Quote from: dsharp02 on March 04, 2016, 03:52:54 amTo put it at easy, you have just been ripped off, send back that expensive paper weight and ask for a full refund.

author: zed65
author_rank: Contributor
timestamp: March 04, 2016, 09:31:47 pm
content: I paid $111 for my unit. (Broken)https://www.eevblog.com/forum/testgear/got-me-a-agilent-34401a-(repair-needed)/

author: smgvbest
author_rank: Unknown
timestamp: March 04, 2016, 10:12:11 pm
content: Quote from: dsharp02 on March 04, 2016, 07:16:13 pmI had same thing with my 34401A and DMMCheckPlus on the AC Current. Once I did the DIAG:POKE 25,0,1 to enable the lower ACI range mine read fine. So if you haven't done that you might try it. You can rig up the serial port I believe to do it over that I understand if you don't want to invest in a GPIB interface.

author: dsharp02
author_rank: Contributor
timestamp: March 05, 2016, 03:59:00 pm
content: Before you did the DIAG:POKE 25,0,1 were you able to select the 10ma ACI range? If you were and it just didn't work, then there may be hope for this meter yet. Hopefully I can get to this sometime this weekend. I have to get to it soon if I want to return the meter.Thanks for your help.Dave

author: markone
author_rank: Frequent Contributor
timestamp: March 05, 2016, 05:32:17 pm
content: Quote from: dsharp02 on March 05, 2016, 03:59:00 pmThis anyway wouldn't explain "The 5v AC from the DMMCheck reads as >5.21v", that implies you have something else screwed up inside the DMM.

author: smgvbest
author_rank: Unknown
timestamp: March 05, 2016, 05:48:57 pm
content: Quote from: dsharp02 on March 05, 2016, 03:59:00 pmNo I was not able to select 10mA ACI range before the poke.Once I did I read 1.00mA from the DMMCheckplus oh don't forget to change your HI(Red) lead to the I plug below the common.I've seen it done where someone forgets to do that on a Amp reading (just incase)

author: dsharp02
author_rank: Contributor
timestamp: March 05, 2016, 09:31:36 pm
content: I've decided to return the meter. I may just purchase a new 5.5 digit meter from Rigol or Siglent. I'd lose a digit but hopefully everything would be functional. I'd love to get a brand new Agilent but can't justify the price.Thanks everyone for your time.

author: markone
author_rank: Frequent Contributor
timestamp: March 05, 2016, 11:16:25 pm
content: Quote from: dsharp02 on March 05, 2016, 09:31:36 pmIf you are a VFD display lover (like me) you can also consider GW-Instek GDM-8351, faster reading rate for 415USD @ TE.http://www.gwinstek.com/en-US/products/Digital_Meters/Benchtop_Digital_Multimeters/GDM-8351

author: HighVoltage
author_rank: Super Contributor
timestamp: March 06, 2016, 10:50:07 am
content: For the price you paid, you can definitely get a good working 34401A. I would just keep looking.

author: tautech
author_rank: Super Contributor
timestamp: March 06, 2016, 12:32:01 pm
content: Quote from: markone on March 05, 2016, 11:16:25 pmInterestingly the specs are very similar between the SDS3055 and GDM-8351 however IMO the Siglent's got it for the display. The SDM3055 does have better capacitance ranges 2nF - 10 k uF and more/better I/O's including LAN and front USB.Saelig's got them in special ATM for $419 and they also do an EEVblog discount.http://www.saelig.com/DMM/M00110009.htm

author: dsharp02
author_rank: Contributor
timestamp: March 06, 2016, 07:25:42 pm
content: Hi Tautech, how would I get the EEVBlog discount from Saelig? I notice TEquipment seems to have dropped Siglent entirely. They had the SDM3055 for $397ish for a couple of weeks, then boom everything Siglent vanished.Thanks,Dave

author: tautech
author_rank: Super Contributor
timestamp: March 06, 2016, 08:07:42 pm
content: Quote from: dsharp02 on March 06, 2016, 07:25:42 pmYep, there was much discussion on that a few weeks ago, dealers do change for whatever reason.In this thread, reply #10, Rick can sort you out or contact Saelig direct.https://www.eevblog.com/forum/testgear/equipment-discounts-from-saelig/You could even contact Alan Lowne the CEO, his email and PM details are at the top of the thread.So if and when you get a discount code, they are not to be made public, but by all means offer them via PM or email.

author: rickv14623
author_rank: Frequent Contributor
timestamp: March 07, 2016, 02:41:21 pm
content: Quote from: dsharp02 on March 06, 2016, 07:25:42 pmDave,Just sent you a PMRick