New YwRobot MB102 power module overheats

louarnold:

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?

MarkT:
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.

ams1117.pdf (71.5 KB)

louarnold: 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..

modellights: 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.

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

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.

modellights:

louarnold: 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!

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

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.

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.

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.

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.

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.

I had a bad experience with this YwRobot MB102 power module too. I accidentally shorted the 5V output for a few minutes and then the regulator got so hot that the top of the AMS1117 blew off with a little bit of white smoke and a lot of bad smell. According to the datasheet of the AMS1117 this could not have happened because the regulator has temperature protection which should have shut down the 5V output. So I bought a (couple of) new AMS1117 on Ebay and repaired the MB102.

To clarify mis-conceptions: The USB jack is reversible - it works as input and output. Plus the female port makes sense, according to USB specs. If you want to power it thru USB, and you don't have a USB male-male cable, but a (more commonly used) USB A-type male to micro-usb male, use an adapter like this:

USB to micro-usb adapter

Hi people, beware of the versions of this board…as I see in the pics, it’s exactly the same as MB V2 (code: 545043) but in the V2 the pdf datasheet mention that the USB is output, not input. “USB connector is for powering external device. Do not attempt to use it to power the MB-V2"”

Which has logic having in mind that the regulator can’t operate with at least 1.5 volts more that the regulation needed.

If it needs at least 6.5 volts, it can’t never operate using the USB port with 5V as input.

I made a test a few minutes ago with 7.5v input, and the USB gives 5v.
The +V of the USB connector is directly the 5V output of the board, NOT the same as the DC IN.
Pins +5V and +V in USB are connected (tested with the multimeter), not the same with the DC IN.

Check it with a multimeter before apply DC to the USB port.

Here I attach the datasheet of the board.

Greetings!

KAOS

electronicsguy:
To clarify mis-conceptions: The USB jack is reversible - it works as input and output. Plus the female port makes sense, according to USB specs. If you want to power it thru USB, and you don’t have a USB male-male cable, but a (more commonly used) USB A-type male to micro-usb male, use an adapter like this:

USB to micro-usb adapter

mb-v2 datasheet.pdf (1.02 MB)

Without load my YuRobot Power MB V2 works fine :D https://youtu.be/sF5Jk7-HpUM

Regarding the overheating AMS1117 chips, it could possibly be due to the properties of unregulated 9V power supplies. I grabbed a random 9V 500mA unregulated supply out of my junk box and got the following measurements under load.

Open circuit 14.21 VDC; 13.7V @ 9mA; 13.2V @ 32mA; 12.3V @ 110mA; 11.3V @ 230mA; 10.35V @ 350mA; 9.00V @ 530mA.

A 9V 500mA unregulated supply is just that. It will give 9V with a 500mA load.

The absolute maximum input voltage for a genuine Advanced Monolithic Systems AMS1117 is 15V. The Chinese version of the 1117 may not be that generous.

The AMS1117 also seems to be happiest when V-in minus V-out is just above 1.5V.
The issue here is the maximum power dissipation capacity of the surface mount chip which is only 1.2W. Power dissipation is determined by the input/output differential and the output current.

In other words if you have 14 Volts going in and 5 volts going out, 1.2 watts divided by the 9 volt differential equals a maximum current of 133 mA before overheating.

However, if you have 7 volts going in and 5 out, 1.2 watts works out to a maximum current of 600 mA.

My advice is to use a small regulated supply of 12V or lower.

The attached graph (if it shows up) shows the digital voltage and current measurements I got on the unregulated supply.

Zapro:
PLEASE note, that the USB connector is connected in parallel with the DC barrel jack

Of course it is not. The USB is connected to 5V output of the regulator and it can be used as both input and output. When USB is used as input then input voltage should be 5V and barrel connector should be disconnected not to power the 5V regulator. Here is another schematics where the connection is more clear.

Addicore YwRobot Breadboard Power Supply.pdf (152 KB)

chupo_cro:
Of course it is not. The USB is connected to 5V output of the regulator and it can be used as both input and output. When USB is used as input then input voltage should be 5V and barrel connector should be disconnected not to power the 5V regulator. Here is another schematics where the connection is more clear.

Well the one i had, it was in parallel. The switch didn’t disconnect the USB-plug. When i put in 9V in the DC-jack it had 9V in the USB-plug.

Zapro: Well the one i had, it was in parallel. The switch didn't disconnect the USB-plug. When i put in 9V in the DC-jack it had 9V in the USB-plug.

Strange. It probably was some badly designed model. On the other hand, I might have such (bad) modules too :-) I didn't check all of them and I order a few now and then from different sources. I burnt one of them just a few days ago, 5V regulator didn't survive accidentally shorted output although it lasted just for a moment. But that wasn't a surprise because I used 12V input.

Regards