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Topic: New YwRobot MB102 power module overheats (Read 6730 times) previous topic - next topic

louarnold

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.

MarkT

Can you post a link to the datasheet or info on this module?  Can you explain exactly how you are testing it?
[ I won't respond to messages, use the forum please ]

louarnold


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.

MarkT



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?
[ I won't respond to messages, use the forum please ]

louarnold

#4
Feb 05, 2013, 10:50 pm Last Edit: Feb 05, 2013, 11:37 pm by louarnold Reason: 1

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.

modellights


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..




louarnold


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.

Yakuzza

#7
May 24, 2013, 08:13 pm Last Edit: May 24, 2013, 08:43 pm by Yakuzza Reason: 1
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

sonnyyu

#8
May 25, 2013, 08:38 am Last Edit: May 25, 2013, 08:40 am by sonnyyu Reason: 1
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.

skippyV



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..





Old thread I know.
According to this site: http://www.petervis.com/Raspberry_PI/Breadboard_Power_Supply/YwRobot_Power_Supply.html the USB connector is an input and he tested it as such.  But I have it hooked up to the barrel supply and have a Mega 2560 receiving its power from the YwRobot USB connector. So apparently it works both ways - as an input power supply and an output power supply!

RadioBob

You stated the inside of the barrel was -ve. The post inside the barrel should be +. I think you have the input power reversed in polarity! That would account for a hot 5V regulator and no heat on the 3.3 volt regulator (as there would be no 5V output from the 5 volt regulator.

RadioBob

Zapro

PLEASE note, that the USB connector is connected in parallel with the DC barrel jack, whick is by the way, Center positive.

If you put 12V DC into the Barrel Jack, you will have 12V in the USB plug - plugging anything USB-related into this will destroy it IMMEDIATELY.

Please take care - almost all those China-boards is made by people that know absolutely nothing about electronics.

// Per.

hshoe007

Gents, I had experienced the same overheating of the 5V regulator, including complete failure.
After reading the spec sheet I noted a comment that the chip is prone to fail if the input voltage
greater than the output voltage .That is the case when the unit is powered by the 3-pin connector.
I soldered a 1N2002 from the output of the 5V regulator to the input of that regulator (anode on
the output).  Have modified four of these modules with no failures or overheating.  Give it a try
if you have a unit lying around.

Zapro


Gents, I had experienced the same overheating of the 5V regulator, including complete failure.
After reading the spec sheet I noted a comment that the chip is prone to fail if the input voltage
greater than the output voltage .That is the case when the unit is powered by the 3-pin connector.
I soldered a 1N2002 from the output of the 5V regulator to the input of that regulator (anode on
the output).  Have modified four of these modules with no failures or overheating.  Give it a try
if you have a unit lying around.


I think you meant the other way around :D

Practically all regulators cannot tolerate their output is more than 0,3V higher than the input, as it reverse-biases the unit, and will surely hurt it.

// Per.

Cactusface

Hi All,
                I have a couple of these breadboard PSU's if you can call them that!!  but I find mine work fine, in the picture attached. I power it from my Uno when at the PC programming, etc via the USB port of course. But then I power it from my bench PSU when doing other things, like testing my project, etc and it powers the Uno!!

I have often reverse powered or connected things the wrong way around!   I  beleive most components are tougher then we think? or is it just LUCK!

Hope it helps, Regards

Mel.
Open your mind! But not too far, your brains might fall out.
Also like Photography, model building and my 300+ Cacti and Succs.

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