V3 Development Board not working

[Sidney]

Hi, My board which I have had for 2 or 3 years now and has worked satisfactorily until today when it reported that it could not ID the onboard chip. On closer inspection I notice that the power indicator LED is not illuminated. Can this be easily repaired?
Regards, Sidney

[DavidA]

Hi Sidney,

Please make sure you are powering the device with the correct voltage and that the jumpers are in the correct position. Has it been working recently? Can you recall any incidents which may have caused a problem?

[Sidney]

Hi David, Thanks for responding. The board is supplied with 13.5V and worked successfully on Monday with a PIC16F877. When I tried on Tuesday with a PIC16F819 it failed. At first I thought it might have been the PIC and I replaced it with another which again failed. It was then that I noticed the power LED on the board was not indicating. A check on Pin 14 on the PIC with a multimeter shows a voltage regularly varying between 1V and 560mV.

Regards, Sidney

[Benj]

Hello Sidney,

Is it possible to check the voltage coming out of your power supply using a multimeter to ensure this is working ok. I would also check the voltage coming out of the 5V regulator with and without a microcontroller chip inserted into the board. Could it be that you have shorted the 5V or +14V signals to anything on the board? If any of the SMD devices have been damaged then a repair is likely out of the question as these are very hard to remove and replace by hand.

[dazz]

As typing this reply in notepad before benj replied,If your board is under warranty disregard my post, if its out of warranty then try it. before breaking out the multimeter, set the board to be powered from usb the led should light(according to the manual) if it lights then start the checks benj mentioned firstly check the following
1 power supply for the correct voltage do this off the board, if this is ok
2 then check for DC voltage at j27(the one labeled 14v on the board) if your getting the correct voltage at this point
3 measure the output at the 5v (j27) connection
If test 1 fails swap the power supply and see if its now ok

if test 2 fails then check for a dry joint on the power connector and at the bridge rectifier

if test 3 fails then do another test j29 pin 1 if this is ok then its likely the voltage regulator is ok
Also check j29 pin2 for a dry joint

if you check that way in conjunction with the circuit diagram you should be able to isolate the fault hth

[Sidney]

Hi Ben and Dazz, Whilst checking the voltage out of the regulator, which was correct, the power LED began to indicate. As far as I am aware I did nothing other than connect the multimeter probes. The regulator appears to be properly attached with good soldered joints. I am sorry for bothering you but thank you for your efforts. I have since downloaded a program to the PIC.

Regards, Sidney

[dazz]

Glad yer up and running, if it does it again poke around the reg with one meter probe and if it springs into life(and its out of warranty) then rewet the regulator joints with solder, but only do this if the problem reappears hth