Owon B35T Bluetooth Multimeter teardown - Page 1
Forum section: electronics / testgear

author: mubes
author_rank: Regular Contributor
timestamp: June 03, 2015, 10:19:59 pm
content: Folks,I have taken a look at the guts of the Owon B35T and posted a few photographs here;https://flic.kr/s/aHskcEJ9Yf.I also did a little bit of testing which is considerably less than exhaustive and certainly not tracable to any kinds of standards. It might be useful to someone but take it all with a pinch of salt...its really just a quick looksee and I reserve the right to backpeddle on anything I've written here! If anyone wants any specific tests carrying out, or a little more certainty, and I've got the kit to do it then drop me a note and I'll see what I can do.Note that I've not tried the Bluetooth functionality yet. In the past some have suggested that it could interfere with readings, but that will take quite some investigation.Leads read 0.4 Ohms on resistance range. Quality is OK but certainly no Fluke.Resistance reading settling time is around 2 secondsPlastics are medium quality. Not great, but certainly not terrible. I don't think the stand on the back will put up with a huge amount of abuse, but it will be fine for home use. The blue 'soft touch' surround is fine. In comparison with UT61e I would say the quality feels slightly less, but there's not much in it.Switch knob is positive, but not quite as smooth as the UT61e.Screen size is really nice.I like the external fuse in the battery compartment. Internal ceramic fuse is rated at 20A/250V.Backlight is great while its on, but useless because it switches off after 10 seconds :-(When abusing the meter with a high frequency square wave it seemed to 'crash' and wouldn't update the display until I switched to another range and back again. I wasn't able to reproduce the problem despite a fair bit of trying.On Ohms, tested against Picotest 3500A, Calib 31 Aug 2012;10 Ohm nominal resisistor reads 10.1 Ohms, Picotest reads 9.886 Ohms.120 Ohm nominal resistor reads 118.7 Ohms, Picotest reads 118.700 Ohms.10K Ohm nominal resistor reads 984 Ohms, Picotest reads 980.27 Ohms.[Ranges are 600.0/6.000k/60.00k/600.0k/6.000M/10.00M/60.00M Ohms, Spec is+/- 0.8%+2Dig except on 60MOhm range where its 3Dig]On DC Volts, against calibration source (calibrated against Agilent 34401A) and Picotest as above;2.50002V source reads 2.494V, 2.5000V on Picotest.5.00114V source reads 4.988V, 5.0011V on Picotest.7.50002V source reads 7.51V, 7.4999V on Picotest.10.0052V source reads 10.01V, 10.0004V on Picotest.Ranges are 60.00mV/600.0mV/6.000V/60.00V/600.0V/1000V. Spec is +/- 0.8%+2Dig.Frequency, square wave, 50% cycle, uncalibrated Rigol DG1022;1Khz source, 0.999KHz indicated2KHz source, 1.999KHz indicated10KHz source, 99.98KHz indicated500KHz source, 499.8KHz indicated1MHz source, 999.7MHz indicated5MHz source, 4.998Mhz indicatedSine wave (the source I had to hand will only do 5MHz square wave);10MHz, 9.997MHz indicated20MHz, 19.99MHz indicated (Note, manual only claims operation to 10MHz).Ranges are 9.999/90.99/999.9/9.999k/99.99k/999.9k9.999M Hz, Spec is +/- 0.8%+2Dig.Duty cycle (1MHz square wave);50% source, 50.1-50.3% indicated20% source, 33% indicated30% source, 39% indicated70% source, 62% indicatedDuty cycle (10KHz square wave);20% source, 20.2% indicated70% source, 69.6% indicatedDuty cycle (1 KHz square wave);20% source, 19.9% indicated80% source, 79.9% indicatedSpec is 0.1-99.9%, +/- 1.2%+3Dig for <1kHz, +/-2.5%+3Dig for >1kHz.Temperature;Reads my body temp as 36 DegC. Not dead yet then.Range is -50DegC to 400DegC, 1Deg resolution +/- 2.5%+3Dig.Edits;4 Jun: Addition of spec/range information.

author: nidlaX
author_rank: Frequent Contributor
timestamp: August 14, 2015, 11:05:07 pm
content: Is it just me, or does this thing have diddly squat in terms of input protection?

author: retiredcaps
author_rank: Super Contributor
timestamp: August 14, 2015, 11:30:02 pm
content: The orange component above the volt/ohm jack labelled RT1 is probably a PTC. PTC is likely only rated to 250V as per manual below.Unfortunately, there are no shots of the other side of the pcb. There may be a MOV on the other side?Note the 36V limit for the Hz function. An oops moment if someone tries to measure the mains AC expecting to see 50 or 60Hz. Much like Martin's UT90C (at around 14:30 mark) ...

author: retiredcaps
author_rank: Super Contributor
timestamp: August 15, 2015, 05:11:44 am
content: I found this video showing how to take apart the B35T in 720p. At 2:13you can see the other side of the pcb. There is no other input protection on this side.

author: Lightages
author_rank: Unknown
timestamp: August 15, 2015, 05:51:32 am
content: It is hard to see any problems with clearances. Without seeing a schematic and doing a real full analysis it is difficult to say for 100% certainty that this would not pass the 1000V CATIII rating tests, but I will stick my neck out and say it couldn't. Under the previous revision of the IEC standards it was allowed to use fuses rated lower than the CAT rating. The latest revision does not allow this. The fuse clips also have to be marked for the type of fuse to be used. It might actually survive over voltage, but who knows?Is it a good meter for bench use? That still remains to be seen in a proper review. Would I buy it for anything else other than low energy electronics use? NO!

author: nachbelichtet
author_rank: Newbie
timestamp: January 10, 2016, 02:47:35 pm
content: Hi there!I'm courious how long the battery of the Owon will last in BT-Mode with a mobile device connected (BT 4.0).Thank you!Markus

author: classical
author_rank: Regular Contributor
timestamp: February 18, 2016, 09:35:42 pm
content: Quote from: Lightages on August 15, 2015, 05:51:32 amIn Germany the meter is sold rated as 250V CAT III. Unfortunately the seller's website is not available in English but you can watch the pictures, the rating is printed on the fronthttp://www.pollin.de/shop/dt/OTUyOTYxOTk-/Messtechnik/Messtechnik/Multimeter/True_RMS_Bluetooth_Multimeter_OWON_B35T.htmlThe German manual also shows 250V CAT III, see page picture page 1, table page 2+3, drawing page 3http://www.pollin.de/shop/downloads/D830740B.PDF

author: ebastler
author_rank: Super Contributor
timestamp: March 17, 2017, 07:25:47 am
content: Considering to buy one of these; they are suprisingly cheap for the feature set. Does anybody know whether the "beep" for continuity testing comes on more or less instantaneous, or whether there is a delay? (In the latter case I would be less interested; hate that in a general purpose meter...)?Thanks!EDIT: This video answers my question (around 3:15 -- beep seems nice and fast):https://youtu.be/iHYxd1OJV9o

author: Wytnucls
author_rank: Super Contributor
timestamp: March 17, 2017, 01:58:17 pm
content: Quote from: classical on February 18, 2016, 09:35:42 pmThey only photoshopped the first two pictures, the others still show 1000V.There is no such thing as 250V CAT III, only 150, 300, 600 or 1000V, with specified impulse voltage tests to meet EN61010 3rd edition regulations.http://www.ni.com/white-paper/5019/en/

author: EEVblog
author_rank: Unknown
timestamp: June 02, 2017, 12:50:09 am
content: What Bluetooth module does this use?It is actual full Bluetooth (capable of serial protocol interface), or BLE?EDIT: Found it, full bluetooth:https://cdn.sparkfun.com/datasheets/Wireless/Bluetooth/CSR-BC417-datasheet.pdf

author: mubes
author_rank: Regular Contributor
timestamp: June 02, 2017, 12:23:17 pm
content: I've given the thing away now but it was deffo full BT...SPP IIRC.Dave

author: savageautomate
author_rank: Unknown
timestamp: November 09, 2017, 01:05:04 pm
content: Quote from: EEVblog on June 02, 2017, 12:50:09 amI believe there is an older revision of this meter ("Bluetooth 2.0 version") that is full Bluetooth and a newer version ("Bluetooth 4.0 version") that is BLE only.I just received a brand new B35T unit and can confirm that it is BLE and not full Bluetooth with SPP.Reference:http://www.owon.com.hk/products_info.asp?ParentID=85&SortID=86&ProID=181

author: Germo7
author_rank: Newbie
timestamp: December 25, 2017, 12:29:38 pm
content: Hej..Intresting is that newer Owon B35T manual is saying for the Hz% measuremant 250 VAC or Equivalent voltage RMS..http://files.owon.com.cn/probook/OWON_35-Series&B41T(+)_Digital_Multimeter_USER_MANUAL.pdfon page 11.