R3 damage due to wrong power suppy

Jammmy_22 · Post by **Jammmy_22** » Sat Sep 15, 2012 7:57 pm

I have (very stupidly) managed to put the wrong power supply into my R£ and now it will not turn on.
The power cable I used was a 19v ac laptop charger, and I am hoping all that is damaged is a few resistors. I have had a look at the PCB and there are no obviously damaged components, although worryingly, there is no protective fuse or resistor set up. Any help with this situation would be much appreciated

kc2ine · Post by **kc2ine** » Sat Sep 15, 2012 8:55 pm

so there is no fuse inside R3? bummer...
can you post a pic from inside? does power supply inlet
sits on separate board or all is on one?

Jammmy_22 · Post by **Jammmy_22** » Sun Sep 16, 2012 9:16 am

<img src="http://i.imgur.com/ioL3o.jpg?1"></img>

the board you see is the main PCB unfortunately. The power input has three pins and each seems to go through a small resistor ( although I cannot find the value of them) The black box with "200 Murata written on it has 4 pins and a loose casing on the top( although I haven't removed this for fear of damaging it) As far as I can tell, this is a current sensing transformer.[/img]

axxim · Post by **axxim** » Sun Sep 16, 2012 2:09 pm

Hi Jammmy,

as far as I can see, there may be one fuse marked F1 (8 pin SOIC-8 at the lower left corner). At least its designator and the way it is routed lead me to think it could be a fuse. Unfortunately the marking of this component is unreadable to me. Even if it is a fuse and it is blown, you have to be aware that also other components may be damaged depending on how the circuit is build and what protections was taken by its designers.
The actual position for that "fuse" is a little unclear for me, but without schematics and without having that PCB in my hands (are there components placed on the bottom side?) it is very hard to make a diagnostic.
Blown components (if thermically overstressed due overcurrent or overvoltage) are usually easy to detect for someone with experience in electronics due their penetrant smell or looking at the surface of the PCB for changes of the flux coating near the solder pads, but unfortunately not all components ever die with this symptoms.

alfredokiwi · Post by **alfredokiwi** » Wed Oct 31, 2012 11:01 pm

The main problem is to find the damaged componet because the R3 don´t use a linear power supply. Is a switching type and because active devices are in use is difficult to repair it. Different scenario would be a conventional one with rectifiers and linear regulators, but due the switching components I recommend to sent it to a technician.

ElektroNoiser · Post by **ElektroNoiser** » Mon Feb 02, 2015 1:43 pm

Hi there, I have the same problem

please somebody help me!

in this video shou the problem:

[youtube]http://www.youtube.com/watch?v=2Xv7zKfc ... tube_gdata[/youtube]

https://www.youtube.com/watch?v=2Xv7zKfcL6M

Thanks![/url]

voip · Post by **voip** » Wed Apr 01, 2015 5:17 pm

A couple of thoughts.

Is the laptop psu plug different from the R3 connector and could it have damaged the connector such that the stock R3 power supply plug no longer makes a proper connection with the socket on the R3?

The muRata part is a choke not a current transformer and there's a possibility it's gone open circuit if excessive current has flowed.

The component marked F1 is actually a switching FET used in the 3.3V supply.

If you have a multimeter handy, then it might be instructive to measure voltages at various points, e.g. C77 and C75 should have 12V across them. Across C113 there should be 3.3V. C67 and C103 should be at 5V. C272 (chip capacitor near the bottom left of the image) should have 0V across it.

.