multimeter Tenma 72-2605 any video tutorial-operating manual

It looks like this multimeter is a rebadged UNI-T UT61A. Here is operating manual for this multimeter:

www.soselectronic.com/a_info/resource/l/UT61English.pdf

This should help.

Thank you very much.Indeed it looks like UT61A. The values of capacitances measured with Tenma doesn't fit at all with the values written on capacitors. I hope UT61A is better than this. Anyway I like its design and is a good product except capacitance.I was especially interested in capacitance and I was dissapointed..Sorry but I have to return it.

What capacitors have you tried and what results did you get - generally a low cost multi meter won't give good results in circuit or with low (< 100pF) caps.

You need to make sure that your fingers don't touch the leads.

Electrolytic and high value ceramic caps can have very large tolerances.

MK

I tested the multimeter by measuring the capacitors directly from a computer video board, so I didn't touch with the fingers.It was electrolytic 470uF and 1000nF,1500nF.The values that I've got it with multimeter was far away different from these.

This is not uncommon. I have seen dried electrolytic capacitors removed from old power supplies with nominal capacity 200uF that measured 100nF.

Were the caps still soldered to the board ?

MK

Ok but the video card is a good one and fully functionally. Also I tried with new capacitors and I cannot estimate from results if there are good.

Can you recommend me a better multimeter?In my new repair centre I need to measure a lot of capacitances with good precision.

Generally speaking you can't measure capacitors in circuit with low cost tools - it can be done for production designs where the cost of test gear is not a problem and there is enough information to set the tools up.

Measuring decoupling capacitors in circuit is very difficult - they are usually in parallel with many other capacitors and shunted by semiconductor parasitic effects.

I'm not sure why you need to measure caps accurately  - for repair work I would expect a DMM to be quite good enough. Why not buy a few polyester caps in the 10nF to 1uF range and check them (5% parts should be available) but if you have some 1% resistors, a sine wave generator and an AC meter (DMM should do) you can calibrate the caps.

MK

Low cost tool means something like this?:http://eu.banggood.com/Wholesale-Warehouse-DIY-M12864-Graphics-Version-Transistor-Tester-Kit-LCR-ESR-PWM-wp-Eu-986954.ht…

For repair, Tenma 72-2605 cannot give me any clue if a capacitor is good or bad. I am not asking big accuracy but to can understand which is good and which not.

I am afraid I don't understand how can a cap be calibrate, but I'll looking for tis on youtube.

No - a low cost (about £140)  tool looks like this:

 

Click To Zoom

Image is for illustrative purposes only. Please refer to product description.

 

 

 

• Manufacturer: KEYSIGHT TECHNOLOGIES
• Order Code: 1780328
• Manufacturer Part No U1701B

•  

• Technical Data Sheet (194.86KB) EN

 

 

A good one is more like the Keysight E4980AL - Keysight blurb below:

 

The E4980AL precision LCR meter is an industry standard LCR meter that provides the best combination of accuracy, speed, and versatility for a wide range of component measurements. The frequency upgrades provide a solid investment option and asset utilization.

Offering fast measurement speed and outstanding performance at both low and high impedance ranges, the E4980AL is the basic tool for general R&D and manufacturing test of components and materials. LAN, USB and GPIB PC connectivity enhances your design and test productivity.

E4980AL supports a variety of accessories suitable for many applications. They are designed to make measurements simple and reliable. Check out the large selection of accessories

Do you doubt if the E4980AL is the best? Check out Low Cost LCR Meter Competitive Comparisons.

For frequency range up to 2 MHz, see E4980A Precision LCR Meter 20 Hz to 2 MHz.

Note: The E4980AL precision LCR meter is available from distribution partners in the world.

 

It's about £3000 but still can't measure one cap accurately if its in parallel with another !

 

MK