Multimeter repair brymen 786

[redwire]

Re: Multimeter repair brymen 786

I find it's all Brymen fanboys over there, any complaint everyone ignores and goes on how great they are and how Fluke needs to run and hide lol. Dave and others are in a conflict of interest selling them for profit.
I'm unimpressed by Brymens and think they're disposable- black-topped IC's, no schematics, no North American parts source for them etc.

This DC power switch, P-ch mosfet Q18 and NPN BJT Q19 with MCU turning on Q19. You can force (override) it on with a say 10k (to +3V) touching Q19 base, see if it powers up. The start-up pulse, not sure what makes that pulse.

In early builds, the rotary switch was defective. No idea what was changed or was fixed by Brymen. Power would cut out. Like in the video I linked to.

[CapLeaker]

Re: Multimeter repair brymen 786

He's already got a repair thread on eevblog with no help. See

https://www.eevblog.com/forum/repair/repair-brymen-786/

Oh! That sux… I would have thought it would generate some interest.

[stj]

Re: Multimeter repair brymen 786

does the mcu have a crystal or resonator?

[ss45]

Re: Multimeter repair brymen 786

Yeah... It was really surprising that I received no reply at all in eevblog.....

Badcaps forum rocks !

[ss45]

Re: Multimeter repair brymen 786

I find it's all Brymen fanboys over there, any complaint everyone ignores and goes on how great they are and how Fluke needs to run and hide lol. Dave and others are in a conflict of interest selling them for profit.
I'm unimpressed by Brymens and think they're disposable- black-topped IC's, no schematics, no North American parts source for them etc.

This DC power switch, P-ch mosfet Q18 and NPN BJT Q19 with MCU turning on Q19. You can force (override) it on with a say 10k (to +3V) touching Q19 base, see if it powers up. The start-up pulse, not sure what makes that pulse.

In early builds, the rotary switch was defective. No idea what was changed or was fixed by Brymen. Power would cut out. Like in the video I linked to.

Thanks for the suggestion
I have tried that. Blank screen

[ss45]

Re: Multimeter repair brymen 786

does the mcu have a crystal or resonator?

There is crystal on the front side of board,
Opposite of side where what assumed to be main mcu is soldered on

[redwire]

Re: Multimeter repair brymen 786

With Q19 forced on, I would check if the MCU has power (at 0R R150 pin 3?) and power appearing across big C86 and C59 (other side of board) 33uF 16V tantalum. Next to look at is the clock.
The DMM IC (BTC M200 034K-0000) has a 4.9152MHz crystal, but I don't see one for the MCU. The crystal region has not so great PC board design, make sure it's clean and no bad connections to it because it's hand-soldered along with the big film cap. The buzzer is also in the way.

I don't see how the MCU gets it's clock, could be RC or it has a feed from the DMM IC to MCU pin 1 or 2, tricky pcb layout.

[ss45]

Re: Multimeter repair brymen 786

Could be... I don't have any interest to pursue it down the rabbit hole.
So I decided to chuck it into junk box.
Not going to touch it anymore.
Thanks for all the suggestions and inputs

[q2q3]

Re: Multimeter repair brymen 786

Hello, you can post the contents of the 24cs04 microcircuit here. It is on a board with buttons.

[JeffreyOG]

I've noticed the same trend with Brymen fans. Any critique tends to get overshadowed by praise, and it does seem like there's a bit of a conflict with sellers promoting them.

[redwire]

Did you try buy a Brymen multimeter in Canada? As soon as you have a problem, toss it in the garbage - return shipping is too expensive.
They are locked out of North American distribution channels. They OEM for Fluke and a few others so I say they are contractually locked out.

[stj]

eevblog is packed with assholes,
you get the same fanboy shit with Fluke even though in the miiltimeter tests the 87 got smoked by the piezo-ignitor instantly and the uni-trend stuff survived it

also they (dickheads) complained that a uni-trend clamp meter wasnt safe because it had no fuses!
i had to explain to those geniuses that the fuses are only on a meter's current range - THAT DOESNT EXIST ON CLAMP METERS. 🤦♂️

[redwire]

I considered buying a Brymen multimeter- but instead bought a used Fluke 87.
The Brymen's have a fair number of problems and I needed reliability as #1. All my Taiwan multimeters (bench/handheld) are shit - either they blow up easy or some issue with the mechanical, display etc. They just aren't good enough.
Having no support in North America is the deciding factor - any repair, calibration, firmware update - ain't gonna happen just bin it.

It was work to tear the Fluke apart and clean it up but the thing works rock solid. Piezo-ignitor won't blow one, most Uni-T, ANENG etc. have no MOV's cheap bastards.
Thing is both Brymen and Uni-T can OEM build really good stuff - but they don't under their own brand name. It's cheapened on purpose, which is kind of sad. Literally $1 to take them up there but they will not spend.

I did not watch the EEV video bashing Fluke and tooting Brymen, in a conflict of interest way. Of course Fluke are grossly overpriced for some time now, a cash cow for Fortive- but they are King of the Hill in a few ways. At least their rotary switch isn't cheap shit.

[stj]

all my ANENG/Zotek have mov's

[redwire]

Not the PTC - is that what you mean? Cheapest DMM's don't use any MOV's. None of ANENG have them AN8008, 870, 301, V8, etc. - no MOV's or proper PCB spacings- so a BBQ lighter kills them easy.
But I find the (real) time a DMM gets hit with a many kV spike is from ESD when you walk around with one and the leads touch something, static discharge in winter.
Working with HV (over 1kV) these cheap meters are off my bench.

UT-61E leaves them out except for Germany, UT-61E+ has three so they finally look decent.

Brymen does have tough input protection and safety certs, matching Fluke.

Multimeter (DMM) information and reviews

[JeffreyOG]

I think Brymen multimeters have their flaws – like those black-topped ICs and lack of schematics. Plus, finding parts in North America is a hassle. Regarding the repair, the DC power switch issue with the P-ch MOSFET (Q18) and NPN BJT (Q19) controlled by the MCU is tricky. You can try forcing it on with a 10k resistor to +3V at Q19's base to see if it powers up. The startup pulse is another mystery – not sure what triggers it. I had issues with early builds too, especially with the rotary switch causing power cuts. Brymen claimed to fix it, but who knows? For those still on the hunt for reliable multimeters (found some info here https://www.cef.co.uk/catalogue/cate...nt-multimeters), it's essential to weigh these factors carefully.

[redwire]

In Toronto but linking to UK CEF website? What's with that.

[CapLeaker]

I am not aware that Brymen has a Canadian nor American dealer. Usually only some Brymen products were available here as a rebranded Greenlee… The Brymen I got, I bought from the EEVblog store. So far so good, I am happy with my Brymen.