I ordered an interesting looking ESR meter recently. I already own a very nice Mastech MS5803, but this unit looked interesting
I ordered mine from here:
http://www.ebay.co.uk/itm/360643330408?var=630113916367&ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649The ESR meter is named the MESR-100 V2 and is made by Jingyan. This is the second Revision of this meter. It incorporates enhancements over its predecessor, the MESR-100 V1 and is built into a more attractive case.
The units details are listed below (from an e*ay sellers page) :
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JINGYAN MESR-100 V2 Auto-ranging capacitor ESR and Low Ohm Meter
Measuring range from 0.001 to 100.0R, support IN CIRCUIT Testing.
Using true 100 KHz sine wave to measure the ESR value, which is equal to the testing method of capacitor manufacturer.
In the market, there is some technique using short pulse method to testing, but the value will be varying vs the capacitance and sometimes reading is different from the manufacturer's value.
What is ESR of capacitor?
There is a series resistor inside capacitor, using 100kHz to remove the impedance 1/(2*pi*F*C), the impedance become small, and we can then measure the true series resistor value.
A bad E-capacitor will have larger ESR and create large ripple rather than filtering noise. Normally, a big capacitor is larger than 3 ohm.
Using this theory, we can measure the capacitor is bad/ damaged or good in condition.
Because our ESR meter only applies less than 15mV DC or peak to peak on a good capacitor, as a result we can use it as in circuit test. Because this low testing voltage, it cannot turn on the semiconductor inside a circuit under testing.
During repairing TV, LCD, Audio board, etc. we can in circuit testing the capacitor is good or not.
*Dual terminal, for fast and easy inspect general capacitor or resistor, a printed ESR table for fast check
Compare MESR100 old V1 and new V2 Improvement:
1) Change square wave to sine wave 100 KHz, reduce square wave’s high frequency component, and affect the reading passing the test leads and capacitor.
2) Higher Resolution up to 0.001 ohm.
3) 128X64 dot matrix LCD, with more larger value display and information
4) Embedded 25V capacitor table at LCD, auto display the capacitor is good or bad reference to common 25V electrolytic capacitor.
5) New plastic case, curve design for hand carrying. New stand for 60 degree stand on desk.
6) Use 2X AA battery, more convenience and longer battery life than 9V battery.
7) Support external USB power, using standard micro-USB port.
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My unit arrived this morning and was promptly dismantled to see what Chinese cleverness lurked inside
On first inspection the MESR-100 V2 looks to be a decent quality plastic case with rear bale for angled desk use. The immediate 'crap factor' that I noted was that the battery cover is retained in place with a small self tapping screw....a screw that cannot easily be accessed without removing the rear bale or bending it up ! A minor annoyance, but an annoyance all the same.
The unit came with two AA cells fitted (poor quality 'heavy duty' cells). These were changed to Kodak Alkaline cells to reduce the chances of leakage damage in the months ahead.
The unit has a nice large LCD display and three large rubber buttons. At the side of the unit there is a mini USB connector for powering the unit from 5V. A nice feature if the unit is to be used on the bench. I have no idea whether the batteries need to be removed when an external supply is used and the manual makes no mention of it. On the front panel there is a table that provides some guidance on expected ESR values for different values of capacitors and working voltages. This is in addition to the units internal electronic database of values for a 25V capacitor.
Upon pressing and holding the on/off power button the user is rewarded with a white on blue start-up screen, then the operational display that contains all the information you need. Mode (Auto range or Manual), Selected Range, Present ESR Reading, Text recommendation on capacitor serviceability based on the measured Capacitance and ESR values. There is a 'Zero' button that starts the units self calibration routine. The leads or test socket are shorted and the unit zero's its display. The test frequency is 100kHz. Any short test leads terminated in 4mm un-shrouded plugs may be used, or leaded components may be connected to the front panel test socket that is located just below the 4mm sockets.
The case is opened by removing four corner mounted self tapping screws. The PCB is secured to the rear case half with four more self tapping screws.
The PCB quality and SMT soldering is of acceptable quality. There is some very average soldering of the interconnect leads from the 4mm sockets to the PCB but these may be reworked easily by the user if required. The PCB appears to have been designed for front panel mounting using the 4mm sockets as there are two large holes for such in the PCB. Interestingly the interconnect wires to the sockets have been soldered directly to the threaded 4mm tubes and not to the solder tabs. This is to reduce the contact resistance that the tabs would introduce into the measurement chain.... nice work ! I was impressed to find that the LCD is a COG type that is secured in place on its own custom mount rather than just 'hot glued' to the PCB as can sometimes be found in cheap Chinese test kit. One electrolytic capacitor has been 'laid down' on the PCB in order to meet the maximum height requirements of the case. Not great but no serious problem in such a piece of test kit. The manual states that the unit does incorporate double diode input protection, but that capacitors should be discharged before testing. At least some effort was put into input protection. The fact that diodes are used across the input does prevent this unit from being used to test battery internal resistance though so do not try using it for that application !
There are unused component positions on the PCB that suggest that the unit may have an enhanced 'brother' in the pipeline or maybe it was just an option that the manufacturer has decided not to pursue ? On first glance it would appear that a USB data output may have been envisaged but not implemented on this unit. The missing chip and crystal would be a USB interface controller.
Having looked at the internal parts, I am of the opinion that this unit is of decent build quality for the price. It has yet to be tested fully but initial indications are that it will do what it claims, and measure ESR. The additionally provided Go/No-Go ESR guidance on the display is novel but of limited use as it is based on generic 25 V capacitors ESR values only. A novel idea though
I personally use a nice large ESR value paper chart as a reference when manufacturer data sheets are not available.
Pictures below:
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