FIXED ! - Brymen BM869S rejecting fresh 9V batteries. - Page 1
Forum section: electronics / testgear

author: rob77
author_rank: Super Contributor
timestamp: June 06, 2016, 08:54:22 pm
content: Hi Guys !did anyone experience a problem with fresh 9V batteries in a brymen BM869S ? i just changed a battery - used a same make of a 9v battery and when turned on the meter was beeping and displaying InERR on the display. that should be the case when the battery is drained and the battery goes down below 5V under 20mA load. but my brymen violently beeps with a fresh battery.i tried a expensive varta long life 9V battery - and it does the same. tested the batteries under 20mA load and they're all above 8,5V under load.with the drained battery the meter works (just showing the battery low sign). so i tried to discharge one of the batteries a bit and once the battery is ~8V the meter works just fine, accepts the battery and starts up normally. the readings are spot on - tested DC volts and Ohms.if someone knows what the heck is going on please let me know.

author: retiredcaps
author_rank: Super Contributor
timestamp: June 06, 2016, 09:06:05 pm
content: Just curious, does this problem happen if you use a DC variable power supply set to 9V? If you are doing this test, what is the current draw?

author: rob77
author_rank: Super Contributor
timestamp: June 06, 2016, 09:20:12 pm
content: Quote from: retiredcaps on June 06, 2016, 09:06:05 pmactually a good ideatested it and it's drawing ~30mA at 9V and the meter starts up, as the voltage is lowered the current draw decreases as well - down to approx 18mA at 6V (all tested without backlight - just the meter itself).don't know what such a meter should draw.. but 30mA looks a bit high to me.

author: wraper
author_rank: Unknown
timestamp: June 06, 2016, 09:22:44 pm
content: Have you tried switching it on with leads removed?

author: retiredcaps
author_rank: Super Contributor
timestamp: June 06, 2016, 09:23:34 pm
content: Quote from: rob77 on June 06, 2016, 09:20:12 pmManual says 6.5mA typical. Time to take it apart and post some clear focused pictures?

author: wraper
author_rank: Unknown
timestamp: June 06, 2016, 09:30:07 pm
content: Quote from: rob77 on June 06, 2016, 09:20:12 pmCurrent is high because it's beeping. InERR is shown when leads are inserted into current sockets but range selected is not current.

author: rob77
author_rank: Super Contributor
timestamp: June 06, 2016, 09:42:11 pm
content: Quote from: wraper on June 06, 2016, 09:30:07 pmit draws 30ma when powered from my bench supply actually works fine (except the high current draw). apart from inErr when the leads are misplaced it also shows inerr when the battery is drained out - it wont let you make bad measurement because of a drained battery.

author: retiredcaps
author_rank: Super Contributor
timestamp: June 06, 2016, 09:48:50 pm
content: Martin's video on the 867 (yes 7, but should be similar to the 9) shows around 4.25mA current. With backlight on, it is around 30mA. Start around the 36:50 mark.

author: rob77
author_rank: Super Contributor
timestamp: June 06, 2016, 10:02:03 pm
content: Quote from: retiredcaps on June 06, 2016, 09:48:50 pmthanks a lot , 867 and 869 are basically the same meter, only difference is that 869 has few extra features and a bit better accuracy.so definitely there is something wrong with my meter it draws ~ 30mA at 9V and 50mA with backlight on. took it apart but nothing obvious there. and i'm afraid that without a service manual or at least schematic diagram it's going to be hard. readings are spot on on DC voltage and resistance (haven't checked the others yet), so the main chipset and the reference should be OK.

author: TheSteve
author_rank: Unknown
timestamp: June 06, 2016, 10:05:39 pm
content: Have you measured its input impedance to see if it is still correct?

author: rob77
author_rank: Super Contributor
timestamp: June 06, 2016, 10:40:39 pm
content: my CEM DT-9935 LCR meter says ~13Mohm on volt range and ~40kohm on mV range when measuring the unpowered 869's input. measuring another meter's input yields very similar figures, so should be ok.going to investigate further.... considering to buy a second bm869s meter to have a reference because i doubt i can find the service manual/schematic...

author: retiredcaps
author_rank: Super Contributor
timestamp: June 07, 2016, 05:25:59 am
content: Quote from: rob77 on June 06, 2016, 10:02:03 pmThree comments/suggestions.1) If Dave can't get a schematic for his eevblog branded BM235, it is likely you won't either from Brymen for the 869.2) I don't know how good these thermal cameras are or even if you can detect a 30mA draw with it, but if you have one, maybe it will show a hotspot?3) I emailed Brymen asking for some component values for the 869 as per this thread.https://www.eevblog.com/forum/repair/brymen-bm869-meets-high-voltage-in-real-world/To my utter surprise, within 24 hours, I got a response. You might want to ask them if they have seen this problem and what is the likely candidate. Point them to this thread. If the likely bad component is not proprietary, maybe they can give you a hint?I sent my question above to info@brymen.com

author: rob77
author_rank: Super Contributor
timestamp: June 10, 2016, 02:38:02 pm
content: i managed to find the little bastard responsible for the current leak. it was a small diode - apparently a protection to dissipate peaks or over-voltage into the battery. it's marked as D13 next to the COM jack. had to de-solder the com jack to have access with hot air to remove the diode.apparently that poor little bastard died while doing his job... it's not rare that i measure 300V DC on a mV range or ohm range... or something stupid like that (because i tend to rush things)... so definitely i killed it, i just didn't realize the fault is there until i had to replace the battery and the meter thrown an error. considering the current draw and the lifetime of a 9V battery it had to be few days before when i was repairing a small computer PSU.

author: retiredcaps
author_rank: Super Contributor
timestamp: June 10, 2016, 02:57:03 pm
content: Quote from: rob77 on June 10, 2016, 02:38:02 pmGood job finding it and more importantly documenting this.I doubt I would have been able to solve this problem if it were my meter. I learned something today.

author: rob77
author_rank: Super Contributor
timestamp: June 10, 2016, 03:06:58 pm
content: Quote from: retiredcaps on June 10, 2016, 02:57:03 pmactually wasn't that hard.. i found approx 200ohm resistance between the + rail and the com jack (- of the battery is switched by the selector switch) , so the suspect was the protection circuitry. fortunately it's just a a 2 sided PCB with narrow (higher resistance) traces so it wasn't that hard to trace and find the low resistance point.

author: pascal_sweden
author_rank: Super Contributor
timestamp: June 10, 2016, 03:40:52 pm
content: Brymen kit seems very fragile then! Shouldn't it manage to take over 1000V?

author: rob77
author_rank: Super Contributor
timestamp: June 10, 2016, 03:57:34 pm
content: Quote from: pascal_sweden on June 10, 2016, 03:40:52 pmnot at all, it's a very robust meter, i'm abusing it for a long period of time and this was the first time something noticeable happened. and actually it wasn't the input protection on the input jacks of the meter, it's part of the input protection of the chipset (dissipating spikes/over-voltage into the battery to protect the chipset). don't forget that on mV range you have the input resistor, PTCs, MOVs , few diodes as a last resort protection and then the ADC.... there is no 10meg resistor network in the path like on the volts range.furthermore that psu i was mentioning was killing itself with spikes - the PFC circuit was killing the switcher with spikes, so no wonder it killed that poor diode in the meter while i was accidentally (actually pretty common for me) "measuring" the 300VDC rail on the mV range (or ohms range).

author: pascal_sweden
author_rank: Super Contributor
timestamp: June 10, 2016, 04:06:03 pm
content: Okey fair enough!Is there any official Brymen supplier in Europe?Even better if it is in Benelux or Scandinavia.Any pointers here?

author: rob77
author_rank: Super Contributor
timestamp: June 10, 2016, 04:24:53 pm
content: only source in europe i know of iswww.tme.eu- i bought mine there.

author: marber
author_rank: Regular Contributor
timestamp: June 11, 2016, 08:03:14 am
content: Quote from: pascal_sweden on June 10, 2016, 04:06:03 pmeleshop.nl sells some Brymen meters.

author: Wytnucls
author_rank: Super Contributor
timestamp: June 11, 2016, 10:31:05 am
content: Quote from: rob77 on June 10, 2016, 03:57:34 pmThe meter must be able to handle 1000Vrms on all ranges, so higher spikes must have killed it.

author: rob77
author_rank: Super Contributor
timestamp: June 11, 2016, 11:12:48 am
content: Quote from: Wytnucls on June 11, 2016, 10:31:05 amactually the spikes could have been over 1kV - the PFC was boosting into no capacitance (dried cap)... and the VSB switcher was killed instantly under slight load (TNY268 with 700V breakdown voltage), strangely the main switcher survived (UC3842+ mosfet)or the spikes were under 1KV but the diode was defective... (but the spikes must have been above 700V because they killed the TNY)another point is - the meter basically survived (in terms of features) and the readings were spot-on, it was just leaking a bit of currentas i mentioned, i didn't even realize the fault till battery replacement.

author: Fungus
author_rank: Super Contributor
timestamp: June 11, 2016, 11:18:37 am
content: Quote from: rob77 on June 11, 2016, 11:12:48 amOn joe's testing thread the BM869S survived up to 5.9KV.https://www.eevblog.com/forum/testgear/hear-kitty-kitty-kitty-nope-not-that-kind-of-cat/

author: pascal_sweden
author_rank: Super Contributor
timestamp: June 11, 2016, 11:19:05 am
content: How come that there are not more Brymen dealers in Europe?Aren't there many dealers from Europe reading about Brymen on this forum?It's a weird observation that it does not take up faster in Europe if it is such a great brand.This makes me conclude that there must be other good alternatives next to Fluke and Brymen, that we don't know about yet

author: joeqsmith
author_rank: Super Contributor
timestamp: June 11, 2016, 12:57:56 pm
content: That's correct but this is a 100uS FWHH exponential decaying pulse with a 2 ohm source. Would a 1mS 2KV pulse damage it? Would a 2KV MOT, I think we have that answer.But I have supplied the Brymen (several times now) with 1KV DC and a 1KVp-p square wave with a +/-500V offset with the meter set to the voltage modes. I have also put a 220V 60Hz full rectified signal into it and rotated the switch through all of it's positions. Plus the grill starter..... It's not the most robust meter I have looked at but it's still by far my favorite portable bench meter.Quote from: Fungus on June 11, 2016, 11:18:37 am

author: Hydrawerk
author_rank: Super Contributor
timestamp: June 14, 2016, 12:49:31 am
content: QuoteSo what meter is more robust? Radioshack? Keysight? Fluke?

author: joeqsmith
author_rank: Super Contributor
timestamp: June 14, 2016, 12:56:16 am
content: The spreadsheet is online. You may find it linked to the very first post.https://www.eevblog.com/forum/testgear/hear-kitty-kitty-kitty-nope-not-that-kind-of-cat/Quote from: Hydrawerk on June 14, 2016, 12:49:31 am

author: matalcacer
author_rank: Newbie
timestamp: April 25, 2018, 03:49:57 pm
content: Quote from: rob77 on June 10, 2016, 02:38:02 pmHello rob77 and all eevblog members !!!My name is Matias and I live in Argentina. My english is really bad !!! Please sorry.6 / 8 month ago I bought one Brymen BM869s multimeter. For more or less 2 / 3 weeks I used the multimeter with the low battery icon on the screen.Yesterday I replaced the battery for a new one (Energizer) and now the multimeter screen only show "InErr" and the buzzer give an alarm warning.This problem is in all meter modes EXCEPT in "TEMP" and "A - mA" modes (Where the test leads must be located on the left connection ports and not on the most common used).I think that this is the same problem that rob77 had and now I have it too. The question is if you can provide information about the diode type and it characteristics to try to buy locally the same diode. I know that I will not find here in Argentina the same SMD diode because is really hard to find locally SMD components. I will try but, if not find, I will need to use and standard hole diode adapted.I'm NOT an Electronic technician, I'm just a handyman with many expectations, desire to do things and limited resources ($$). I hope that you can help me.Thanks a lot !!!!Matias.

author: jamesd
author_rank: Newbie
timestamp: December 05, 2018, 10:04:33 am
content: Could you tell me the specification of the diode at D13?..actually a brief update since I posted... I had dirt from a wasp nest in the left 'A' input!I had been in touch with Brymen and they responded to me within 4 hours with a suggestion to clean both inputs. They were quick to help and spot on with their suggestions. I cleaned the inside of the input plug with a cotton bud and solved the issue.Here is their suggested solution in case other users have the same issue:Quote