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10 years, 4 months ago.
I have a problem with my mbed.
I unfortunately destroyed my mbed by bringing +5V voltage to pin(p24) that was set as output. In that moment LEDs turned off and my MBED stopped working. When I connect it to PC mbed is not recognized.
I have questions: Is broken only LPC1768 chip? or Could be destroyed more components on mbed?
Can I repair it by soldering new LPC1768 chip? Will it work?
I know it is really hard work to solder that chip, but if it is possible to repair it that way I want to try it.
Please for ideas.
Vojtěch Kolomazník
4 Answers
10 years, 4 months ago.
I am surprised it damaged it in the first place: the LPC1768 can survive a short circuit (as long as you don't do it with too many pins and go over the thermal limitations). Granted it is specified for tying a low output to 3.3V, but considering it is 5V tolerant I wouldn't expect it to die, let alone do it directly.
Could you repair it by soldering a new LPC1768 on it? If that is the issue: yes. It uses a regular LPC1768 without special code on it, so soldering a replacement on it should work, if that is indeed the broken part. But at the same time it shouldn't prevent the mbed from being recognized, unless it is now a short circuit for its power supply.
Something to do first: Remove USB power, hold reset. Keep holding reset. Plug it in your PC. Keep holding reset. Does it now show the mbed drive again? If yes, upload something like a blinking led program.
10 years, 4 months ago.
I removed USB cable, and holding reset i plugged it it my PC, but PC does not show the mbed drive.
Can PC recognizes mbed drive when LPC1768 chip is broken? or, there is another component broken and that is the reason why pc does not recognize mbed??
Before i solder new LPC1768 chip.. Can i send it back to shop, for reclamation?..
(really sorry for bad english)
10 years, 4 months ago.
You said the LEDs turned off when you caused the short. Is the power LED (the one closest to reset button) still working ? When that LED does not work you wont be able to connect with the interface chip and mbed wont be recognised by the PC anyway.The 3V3 voltage regulator for the LPC1768 and interface chip may have been blown. Are you able to measure and check voltage on 5V and 3V3 pins of the regulators?
No, power LED (near RESET) is not working.. But you have a great idea to measure that :) . I will measure that on Thursday and write results as soon as possible. If the 3V3 voltage regulator is damaged - no problem. But in case of damaged interface chip.. I think I would not be able to only find which one have been blown... thanks for great ideas :)
posted by 07 Jan 2014