It is depressing how often the obvious answer is given and ignored on this forum.

Yeah. Post #2.

 

I would appreciate if you would show more self control. I often sort through regulators that way and with good success.
Most people here can pick up a multimeter and a voltage regulator and find the IN, Out and Ground. on the diode selection.
Either you are incapable of making it work or you need a new multimeter but insist on knit picking.
It may not be as common knowledge as I thought but I get things done quickly by using that method using Zoyi ZT219T
Using the select mode click click click I am done I have the numbers I need.
Now I just lost time explaining to someone making belittling remarks, also recall you made false statements about me on another thread,
kindly mind yourself. If you remind yourself more often that you are not superior and need to recognize boundries.


Makes no sense... DMM diode test is used to measure Vf of a PN junction using DMM as power source. It works by providing low voltage (typically up to 3V or so) and current on the order of few mA.
Measuring voltage across input or output of the voltage regulator requires DMM to be set to DCV mode. In this case DMM is not supplying any power and current through DMM is in nA. That is several orders of magnitude different.

The TI data sheet shows this internal circuit of the old LM7805. I choose a quick multimeter check method on this.
I do not claim to be a voltage regulator expert. I agree, the AMS will do that and possibly add a source follower as needed.
It is about supporting his contribution to improve the ESP supply, glad to see the website. It represents effort.
At 2 minets Chip Gracey talks about using his apple II to commadore 64 he was age 14

View attachment 335592


Panic Mode's criticism is not worth believing it is a very poor excuse for his compulsion to be irritating and nosey.

Hi,

Not sure what you guys were talking about, but using a diode test function on a multimeter to test anything but a diode constitutes only a sort of sanity check which measures the simplest thing only and can not provide us with a definitive test for a more complicated device. Even using a diode test for a regular NPN transistor is not a definitive test, it just gives a rough idea if the device 'might' still work or not. The only conclusion would be if it failed the diode test then the device is bad, but if it passes the diode test then it is still not clear if the device is working right or not as a more sophisticated test would be required.
You'll note that the better DMM's have a 'transistor test' socket to test the approximate beta of a transistor, which was added along with the regular simpler diode test. The reason was that the diode test isn't enough even for a regular bipolar transistor (NPN or PNP).

It's not too hard to test a regulator chip you just need an input source and load, and be sure everything is connected properly.

 

I would appreciate if you would show more self control. I often sort through regulators that way and with good success.
Most people here can pick up a multimeter and a voltage regulator and find the IN, Out and Ground. on the diode selection.
Either you are incapable of making it work or you need a new multimeter but insist on knit picking.
It may not be as common knowledge as I thought but I get things done quickly by using that method using Zoyi ZT219T
Using the select mode click click click I am done I have the numbers I need.
Now I just lost time explaining to someone making belittling remarks, also recall you made false statements about me on another thread,
kindly mind yourself. If you remind yourself more often that you are not superior and need to recognize boundries.


Makes no sense... DMM diode test is used to measure Vf of a PN junction using DMM as power source. It works by providing low voltage (typically up to 3V or so) and current on the order of few mA.
Measuring voltage across input or output of the voltage regulator requires DMM to be set to DCV mode. In this case DMM is not supplying any power and current through DMM is in nA. That is several orders of magnitude different.

The TI data sheet shows this internal circuit of the old LM7805. I choose a quick multimeter check method on this.
I do not claim to be a voltage regulator expert. I agree, the AMS will do that and possibly add a source follower as needed.
It is about supporting his contribution to improve the ESP supply, glad to see the website. It represents effort.
At 2 minets Chip Gracey talks about using his apple II to commadore 64 he was age 14

View attachment 335592


Panic Mode's criticism is not worth believing it is a very poor excuse for his compulsion to be irritating and nosey.

Panic Mode's explanation of why doing a check the way you described is largely pointless was quite relevant.

Look at the circuit you posted. As you described your connections, what you are measuring is dominated by the voltage drop across D1, R1, and then probably Q1, Q15, Q16, R16. I'm making an inference here based on the assumed characteristics of Q11. But, if correct, that would result in an expected voltage drop of about 2 V to 2.4 , which agrees with what you are seeing.

But that "test" tells you little to nothing about whether the device is good. It "might" let you make some educated guesses as to which pin is which, or at least which functions a pin can't be, but that's about it.

The meaningfulness of this "test" also relies on the schematic in the datasheet accurately reflecting the circuitry on the chip, which is often not the case (the schematics are often simplified to some degree). Furthermore, it assumes that your "test" is not interacting with the I/O protection circuits, which is seldom a good assumption.

 

I have never heard of using a multimeter diode check to verify a regulators specs or pinout. It could tell you if it's shorted and ready for the garbage bin but that's about it.

 

I am sorry for assuming panic modes intention was bad.

The LM7805 was described and L7805 in the context of being less favorable. TS stated AMS1117-5 and 3.3 was considered as replacement.
Because the voltage going IN may not have been sufficient Bob commented it should be at least 7.6 That sounded good, check if the regulator in and out were correct. In the context of what was said before. I use a multimeter diode selection the numbers tell me if I have the pin right.
I expected that the TS would try that before trashing the circuit. Use the numbers make sure there is adequate voltage. Sorry if the conversation
is taken to mean I am analyzing the LM7805 with a diode checker. The paragraph quote left out what was above. The comment about why diode check might work was explained. People came and said some funny things. We all make mistakes. Why not take a few different regulators and try it.