Multifunction tester

[Gaber Mohamed Boraey]

Hello
Please see this photo as I've just purchase this tester and I don't think it's like my expectations before I buy

Anyway, I bought and need your opinion about it

It came without manual, so I don't know the range at which this device work, as I've noticed that it work fine with some components and not with others
As you see at the pboto6, I test IGBT and it only read doide, I test Thyristor and it only read resistor
While I measure mosfet 20N60, it read right
How you think?, is it a bad component which give fault readings?, or the device can not recognize?
As that IGBT I just purchase from local supplier and I already installed in the machine and it does its job, so why device give wrong read?

 

[stenzer]

Have yo tried a google search with "t7 multi function tester manual"?

 

[danadakk]

These are low end testers. so they do not check anything that is or requires high voltage.
Like breakdown V in the 100's of volts. They are simply very gross testers.

https://www.joy-it.net/files/files/Produkte/JT-LCR-T7/JT-LCR-T7_Manual_2023-09-21.pdf

As you can see in the manual they dont even tell you what I and V they test at. User enters no part info, like
part number, specs. Very gross tests. Systems that truly test a parts specs in the $100's of thousands.

Its not a Mercedes, it is a scooter missing the wheels and handlebar.

Regards, Dana.

 

[pjmelect]

These little testers are very useful devices, although it is true they don’t test the full range of parameters of the device under test they do give a simple good or bad indication of the device and are very useful in fault finding. They do have problems with some types of MOSFETS or similar devices. The main problem in using them is ensuring that you have made a good connection with the leads.

 

[Gaber Mohamed Boraey]

These little testers are very useful devices, although it is true they don’t test the full range of parameters of the device under test they do give a simple good or bad indication of the device and are very useful in fault finding. They do have problems with some types of MOSFETS or similar devices. The main problem in using them is ensuring that you have made a good connection with the leads.

You mean if fault readings maybe because bad. Contact between the mosfet and the device?

 

[betwixt]

You have to consider they use a small MCU (mine uses an ATMEGA328P) which runs on low voltage. Basically they try different combinations of connection to find out what the device is but can only apply a small voltage to see what combinations appear bidirectional (capacitor, inductor, resistor) and which only conduct on one direction (diode, scr, bipolar and mosfet). Repeating the measurement after a short delay will differentiate between resistors/semiconductors and reactive components.
Anything needing more than about 3V to make it conduct will read as an unrecognized component. They are excellent little gadgets for quick tests as long as you acknowledge their limitations.

For more comprehensive checks you have to use the test model in the components data sheet.

Brian.

 

[danadakk]

They can do Zeners to 30V, otherwise everything is low V.

Knight.

 

[pjmelect]

You mean if fault readings maybe because bad. Contact between the mosfet and the device?

Maybe, try swapping over the test leads to the device under test. Test the tester by shorting out any two of the leads and them another two of the leads.

 

[dpaul]

It came without manual, so I don't know the range at which this device work, as I've noticed that it work fine with some components and not with others

For good quality measurement work, I would never buy such cheap s**** stuff.
Return it back if you not missed the deadline.

 

[Gaber Mohamed Boraey]

Maybe, try swapping over the test leads to the device under test. Test the tester by shorting out any two of the leads and them another two of the leads.

I think it's connected good, I think it's the limits of the tester just can not reach the component values and then give only what parameter he see in the component

 

[ebhvw]

Hello
Please see this photo as I've just purchase this tester and I don't think it's like my expectations before I buy

Anyway, I bought and need your opinion about it

It came without manual, so I don't know the range at which this device work, as I've noticed that it work fine with some components and not with others
As you see at the pboto6, I test IGBT and it only read doide, I test Thyristor and it only read resistor
While I measure mosfet 20N60, it read right
How you think?, is it a bad component which give fault readings?, or the device can not recognize?
As that IGBT I just purchase from local supplier and I already installed in the machine and it does its job, so why device give wrong read?

View attachment 193212

 

[ebhvw]

How about this?

 

[betwixt]

They are good as go/no-go testers but all they do is place a small voltage across the pins in different combinations to see which ways it conducts. For capacitors it times how long they take to charge, for inductors the time for a determined current to flow and for resistors a simple ADC reading in a potential divider. The maximum voltage they can apply in any direction is about 5V so any device needing more than that to start conducting will not show properly. In the case of an IGBT, it probably doesn't understand the current paths through it so comes to the wrong conclusion it is a diode.

Brian.

 

[Gaber Mohamed Boraey]

They are good as go/no-go testers but all they do is place a small voltage across the pins in different combinations to see which ways it conducts. For capacitors it times how long they take to charge, for inductors the time for a determined current to flow and for resistors a simple ADC reading in a potential divider. The maximum voltage they can apply in any direction is about 5V so any device needing more than that to start conducting will not show properly. In the case of an IGBT, it probably doesn't understand the current paths through it so comes to the wrong conclusion it is a diode.

Brian.

Yes out of range for the tester