DMM Brymen BM869s

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This is the top Brymen meter with very high precision and PC connection (Must be bought separately).

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The meter arrived in a cardboard box that is used for the two top models, on the back is a table comparing them.

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The box included the meter, two probes, a thermocoupler (Meter supports two) and the manual (It can also be downloaded).

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Probes are branded with B.T.C. and has removable tip covers.
The probes are rated for up to CAT IV 1000V like the meter.

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The plug is fully shrouded and standard probe plug size.

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A standard thermocoupler with a standard dual banana connector.

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The meter is heavy and the tilting bale can hold it while the range switch is used or the buttons is pressed.

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The PC connection is here with an optical link.

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The tilting bale can be moved a bit and then be used to hand the meter on.

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The rubber sleeve must be removed to replace the battery




Display

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The above picture shows all the segments on the display.
There is a 4 digit, a 6 digit display and a bargraph. Only 5 of the 6 digits are usual used, in DCV it is possible to activate the last digit. The small display and the bargraph will only be used in some ranges, see end of this chapter.

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Normal DC voltage with voltage and bargraph.

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In some AC modes the small display will supplement the large display.

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With this display the meter could not maintain the bargraph.
The bargraph will not be show when the secondary display shows voltage or current.

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Current with a 4-20mA percent supplement.
Dual and single display functions (After / is small display):
VAC VFD: VAC/Hz, Hz/VAC
VAC: VAC/Hz, dBm/Hz, Hz/VAC
VDC: VDC, VDC/VAC, DC+AC/VAC
mVDC: mVDC, mVDC/mVAC, mDC+mAC/mVAC, Hz, Duty Cycle
mVAC: mVAC/Hz, dBm/Hz, Hz/mVAC
Temp: T1, T2, T1/T2, T1-T2/T2 (Use RANGE to select)
mA: mADC/%4-20mA, mADC/mAAC, mDC+mAC/mAAC, mAAC/Hz
A: ADC, ADC/AAC, DC+AC/AAC, AAC/Hz
uA: uADC, uADC/uAAC, uDC+uAC/uAAC, uAAC/Hz



Functions

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Buttons (Range selection and a few other are remembered): Rotary switch: dB reference impedance: 4, 8, 16, 32, 50, 75, 93, 110, 125, 135, 150, 200, 250, 300, 500, 600, 800, 900, 1000, 1200



Input

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Measurements 1uF

A look at the capacity measurement waveform.

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Frequency input resistance, this is similar to mV

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Software

The software must be bought separately.

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The box only includes a cable and a CD. The CD contains software for many different meters and also files describing the data format (It is the display segments, not digits that is transmitted).

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The opto adapter has two leds and some mechanic to lock it securely in place.

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Here it is mounted on the meter.

1s

The software is one top bar and initially four independent windows.

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Here I am connected to the meter and read data.
The data can be saved from the chart window in either an internal format or exported to a image or CSV file.

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The different windows in the meter software can be closed and moved independent, except the title and command bar.

3

Here is the export dialog. There is another menu to adjust the logging interval.

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The CSV file is fairly easy to read.

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And if the meter is using the dual display it will log two sets of data for each line.



Tear down

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4 screws and the front could be removed (This time it was not the back). The screws do not fall out, but stays in the holes.

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There are pads for 8 buttons, but the meter only has 6 buttons? There is also space for an extra chip.

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On this image it is possible to see that the missing buttons are marked UP and DOWN

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To get the electronic out I had to remove one more screws (There are holes for two).

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The back of meter is shielded and the buzzer is mounted outside the shield.

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On this side there are a couple of springs for connection to the shield and buzzer and also two leds for the computer link.

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I had to remove four screws around the range switch to take the two circuit boards apart.

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Around the center fuse (0.44A) is four diodes for protection of the mA and uA shunts, there is also the input terminal sense resistors (R6abcdef: 6x2Mohm). The ones for the 10A range is below the 10A fuse.
The voltage input has two paths with resistors (R1 & R2 and R3 & R4) each followed by a ptc (PTC3 & PTC?) and clamped to minus by some MOVS (SPG1 & SPG2 + SPG3). There is also 3 pairs of transistors (Q3 & Q4, Q5 & Q6, Q7 & Q8) that can be switched in.
The voltage divider and multimeter chip is below the shield, that is soldered to the circuit board. The big capacitor (C1) is the AC input capacitor.
Some interesting chips are the reference (U4: REF43G), a analog switch (U11: 74HC4053D), a voltage converter (U7: HT7660), a OpAmp (U14 & U15: MCP602I), rms to dc converter (U12: AD636JHZ).

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Two screws more and I could pull the display off.

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On this board is the main processor and a EEPROM to store calibration (U5: S24CS04A)

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Only the connectors and the range switch on this side. The range switch is a bit interesting, it has 8 circles of contact points, but in the range switch there is only switches to cover 4 circles?

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Conclusion

This meter has a lot of protection and mounted the right way, it do also have very large fuses.
All the common ranges are present and also a lot of extra functions like Peak, Average, Dual-display, AC+DC. This makes it a very universal high end meter with just about any desired function. In the volt ranges the range switch is a bit overloaded (All 5 volt ranges can measure AC) and it may take some time to get it straighten out what range to use for what with AC, all other ranges are logical enough.
The meter is not really specialized for electrician, industrial, HVAC, audio or electronic, but is mostly perfect for all of it (The missing Low-Z mode may give a minus point for some areas).



Notes

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