AD584LH Transparent Acrylic Finished Precision Voltage Reference Malfunction - Page 1
Forum section: electronics / projects

author: diyaudio
author_rank: Frequent Contributor
timestamp: January 15, 2015, 12:12:36 pm
content: I bought a precession voltage reference never used until now recently, it worked for a few days, tested with my fluke 87 all reference measurements passed.problem is I left it over night, connected with the power "on" to the input of my ADC board im busy prototyping, now the device is completely useless, all reference measurements are out.2.500 are now +/- 6.00, 5.00 now +/-11.81, 7.500 now +/-12.41 and 10.000 now 12.80wtf what happened ? anyone know how to fix this unit, repair it ? I need it for my ADC circuit as I have no precession voltage reference to work from.checked the battery, works 3.7Vcheck loose connections.checked everything except the reference itself i figure some thing must have pumped voltage back into the circuit and blown the reference chip killing it softly.help comments always appreciated.

author: dannyf
author_rank: Super Contributor
timestamp: January 15, 2015, 12:29:59 pm
content: QuoteFried by transits on the power supply? Overheating? It is a PoS? Your cat pee'd on it? ...I would figure out its schematic and probe it to see what might have gone wrong.

author: diyaudio
author_rank: Frequent Contributor
timestamp: January 15, 2015, 12:30:04 pm
content: The alarming part is the AD584LH cost $13,08 freaking hell.http://za.rs-online.com/web/p/products/7590844P/

author: diyaudio
author_rank: Frequent Contributor
timestamp: January 15, 2015, 12:31:55 pm
content: Quote from: dannyf on January 15, 2015, 12:29:59 pmCant say for sure, surely not the cat!

author: mij59
author_rank: Frequent Contributor
timestamp: January 15, 2015, 12:47:50 pm
content: Check the supply voltage of the AD584.Maybe there's a problem with the feedback, probably done with mosfets.Remove the AD584 and test it.

author: dannyf
author_rank: Super Contributor
timestamp: January 15, 2015, 01:20:50 pm
content: QuoteThe neighbor's cat then?The point is that there is an endless list of how this thing could have gone wrong.Unless you do some investigation, no one is going to tell you with any level of certainty what exactly went wrong.

author: diyaudio
author_rank: Frequent Contributor
timestamp: January 15, 2015, 03:28:31 pm
content: Quote from: dannyf on January 15, 2015, 01:20:50 pm@dannyfThe point is this, vie seen lots of these units floating on the forum, also with various issues, I just took a leap of faith and asked for help maybe someone here had similar issues, keep your arrogance to yourself next time, if you have nothing useful to say, say nothing you not doing me a favour.@mij59Anyway, im busy de-soldering the voltage reference will stub a test rig on my breadboard, the datasheet says a maximum of 40V. the small boost converter measures from 3.7V to 12V so all the rails are present as per the datasheet, maybe the unit is using a fake reference who knows.

author: SeanB
author_rank: Super Contributor
timestamp: January 15, 2015, 04:05:09 pm
content: Pull battery connection, leave off for a half hour then connect battery, then plug in the USB. It should restart fine.

author: diyaudio
author_rank: Frequent Contributor
timestamp: January 15, 2015, 04:39:36 pm
content: Quote from: SeanB on January 15, 2015, 04:05:09 pmNope, looks like the ic is shot, just de-soldered the ic and applied voltages to the relevant pins. i even opened the can, looks legit. im ordering a new ic from rs components.

author: SeanB
author_rank: Super Contributor
timestamp: January 15, 2015, 05:20:59 pm
content: My one has been powered pretty much since I got it, aside from a few instances where the internal battery went flat from Eishkom taking a holiday. Still as good as when I got it, the drift figure is more likely the DMM used to measure than the reference drifting.So your one died an early death then.

author: Conrad Hoffman
author_rank: Super Contributor
timestamp: January 15, 2015, 07:20:49 pm
content: No idea what your climate is, but here in the winter I'd never put a precision anything in an uncoated plastic case. With low humidity you get static discharges every time you handle something, even if you don't feel it. Search ESD and "walking wounded". It's common for ESD damaged parts to work for a while, then fail. I can't say if the plastic caused the problem, but it's not a good choice.

author: diyaudio
author_rank: Frequent Contributor
timestamp: January 15, 2015, 07:53:58 pm
content: Quote from: SeanB on January 15, 2015, 05:20:59 pmHopefully it shall be fixed in a few days time, R130 for the bugger, locally Mantech Electronics Cape Town yields zero.@Conrad HoffmanClimate? well its summer here in Cape Town, good point it was rather hot yesterday when it died, but ah don't care Im fixing the bugger.