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[on:]

I purchased a YWRobot M102B Power Module, and received it only a few days ago. While testing it, I immediately learned that the 5V regulator is, within seconds, too hot to touch. And this was without any load whatsoever. I used the same power adapter as I use for the Arduino UNO whose 5v regulator doesn't get hot at all. I assume then that the module must have some wiring error in it - such that a strong load is created. As the PCB is multi-layer, I doubt that I'll be able to fix the problem. Any suggestions - outside of returning it or discarding it?

Note: The USB connector is female and, of course it should have had a male connector.
The UNO regulator (ON 117-5) and that of the power module (ASM-1117-5) appear to be the same although different brands. The Max input voltage is 15 V, and the power adapter is under that.

[Reply #1 on:]

Can you post a link to the datasheet or info on this module?  Can you explain exactly how you are testing it?

[Reply #2 on:]

Can you post a link to the datasheet or info on this module?  Can you explain exactly how you are testing it?

I have attached a photo and what I think is the schematic for this version of the board. That's all I have.
To test it, all I did was to insert the power adapter plug into the black socket on the board. I did not connect anything to the supplies, and in fact jumpered both sources to an off position. The 5 v regulator heats to untouchable in 2-3 seconds.

[Reply #3 on:]

Can you post a link to the datasheet or info on this module?  Can you explain exactly how you are testing it?

I have attached a photo and what I think is the schematic for this version of the board. That's all I have.
To test it, all I did was to insert the power adapter plug into the black socket on the board. I did not connect anything to the supplies, and in fact jumpered both sources to an off position. The 5 v regulator heats to untouchable in 2-3 seconds.

So what "power adapter plug" - what polarity, what voltage? - and is there a manual / datasheet for this module? 
Is the polarity of the barrel jack socket marked / indicated (believe it or not these things are not standardised).

It does sound like a short circuit at the 5V side of things - do you have a multimeter?

[Reply #4 on:]

So what "power adapter plug" - what polarity, what voltage? - and is there a manual / datasheet for this module?  
Is the polarity of the barrel jack socket marked / indicated (believe it or not these things are not standardised).
It does sound like a short circuit at the 5V side of things - do you have a multimeter?

There is no manual or datasheet for the product and no other info. Its from China; need I say more?
The adapter is an over the counter unit with an nominal output of 9 VDC at 800ma. The open circuit voltage is 13.5 V. I use the same adapter as the supply for the Arduino UNO board. The interior of the barrel is positive.
The 5v regulator is designated as ASM1117-5 whose datasheet I have attached.
I have followed the circuit on the schematic from the input adapter plug. The socket's center goes to the 1117-5 input pin 3; pin 1 is connected to ground and pin 2 is (at least) connected to the green LED. For a green LED voltage drop is typically 2.2v. So for a 5V supply the current through the resistor is (5-2.2)/470 = ~ 6 mA. So it must be something else.

I've traced through the rest of the connections and they all appear to be OK, but there is about 180 ohms between the 5V rail (1117-5 pin 2) to ground as measured with an ohmmeter. Reversing meter leads produces the same results. I can't think of what might cause that, but it would draw only 27 mA from the regulator whose max current is ~1 A.

There is no similar resistance between the 1117-3 regulator output and ground. Removing jumpers does not eliminate the 5V, 180 ohm shunt, nor does changing the DPDT switch.

[Reply #5 on:]

Note: The USB connector is female and, of course it should have had a male connector.

Actually I think not, and almost everyone on the net has assumed the function of this connector backwards.  It isn't an input to power the breadboard, it's an output to power something like an off breadboard Nano with a USB cable from the 5v regulator.  The only power in is the coaxial jack..

[Reply #6 on:]

Actually I think not, and almost everyone on the net has assumed the function of this connector backwards.  It isn't an input to power the breadboard, it's an output to power something like an off breadboard Nano with a USB cable from the 5v regulator.  The only power in is the coaxial jack..

Yes, you are very likely correct. I didn't realize that until a few days ago. The female connector always bothered me. How could someone make such an obvious mistake?? Of course,its not a mistake. Now I'm gonna be stuck with a maleA-to-maleA adapter. Hahaha!

Its very very good that you spoke up. Thank you.

[Reply #7 on:]

i also experience an overheatingissue with a 9v adaptor, as you describe the regulator is untouchable within a few seconds, any further information on that subject till now ?

i do have on the AMS1117 5.0

GND->Vout = 86 Ohm
GND->Vin = 57 Ohm
Vin->Vout = 126 Ohm

as an example of the 3.3V regulator (not overheating one)

GND->Vout = 1080 Ohm
GND->Vin = 86Ohm
Vin->Vout  = 1165 Ohm

[Reply #8 on:]

OK, same AMS1117 5.0 at Shenzhen market could cost  0.05 USD or 0.15 USD at qty, go figure yourself why. I did not say anything.

if I were you, buy one LM1117 5.0 from digikey for 1.10 USD, then replace the AMS1117 5.0 and move on.