no network activity leds

[tbone321]

Make sure that when you cleared the bridge that you didn''t completely open the connection as well.  A solder sucker can do that pretty easily if all of the contitions are right.

[RJ]

Yes solder suckers are not a good idea on SMD. Wick is the prefered way since it is hard to pull all of solder out of a joint with it.

Look for any "dry" pads to pin areas now.

RJ

[Dennis Cherry]

• get better light and magnifying glass
• use flux and braid to do thorough check around the SMT chips
• reflow all of the connections --  add more solder with sufficient heat to get it to come through to the other side of the board
• clean up solder spatter
• check voltages:
  
  • crystal voltages (Xtal should read 3.3 volts between pins 4 and 8 and 1.6 volts (approx) between pins 4 and 5 )
  
  Did you verify the Pic chip is programmed with the correct code?
  
  • 5V regulator (7805): 7.98V on pin 1, 0V on pin 2 and 5.00V on pin 3
  • 3.3V regulator (117v33): 0V on pin 1, 3.29V on pin 2 and 5.00V on pin 3

 

There did seem to be some bridging on the PIC.  I used flux and then the solder sucker and it now looks good.
I tested the regulator and 50 xtal voltages described above -- and they are good.

So, I've run out of ideas.  it still doesn't work.

To summarize -- I have 3 units that show life on the magjack, but unit #4 does not.
I know that the cable is good (because of the success of units 1-3).
The power LED on units 1-4 ALL come on.
voltages on 50 xtal, and each regulator all match the numbers aboe.

Other tests to try out?

[caretaker]

I am in the same boat as Steve, I finished putting together my second ED and after programming the PIC successfully I plugged power into the ED and the green light came on right away which I new was not right. I then tried plugging an ethernet cable into the MAGjack and no lights lit on the MAG jack and there was no connectivity on my switch.  I checked the voltage regulators and get 4.99 off the 7805 and 3.35 off the 117v33.  The Xtals check out fine at 3.3 on the inputs and 1.67 on pins 4 and 5.  I went around the board and retouched everything. I also went around the edge of the Network chip with flux and solder braid and well lests say I won't be doing that again, I did seem to get all the bridges that formed on the one side cleaned up but I am not happy with the results.  Needless to say when I plugged the ED back into power I got the same results, Green LED comes on right away and nothing on the MAGjack when plugged into the switch. (Yes the cable and switch are good as my other ED works just fine).  Attached are pictures

[RJ]

If the pic is programmed you should have got the green led. This was not incorrect it sounds like it was fine. This could be a cable issue or something simple like that. But you will have to be careful you have not added a solder issue on the chips now. I see a lot of solder laying around near the smd chips.

Some of the solder joints look a little blob like. And there seems to be a lot of flux all over the pcb bottom.

I would clean the pcb with 91% alcohol (get it at walmart/walgreens, ect) and a brush and then turn you iron up another 10 deg and then use a little tiny bit of flux from a pen on the joint if you have one and then reheat the joint till it flows clean and shiny like mercury(under 3 sconds if all is correct) do not add any more solder there is more than enough there to use. Then move to the next joint and do the same.

For everyone if your pcb came from the scond batch you should have a very good reason before you mess with the solder on the chips. They were check very well and were placed by machine and reflowed in  temp controlled oven. There should be little issue with those pcbs. I just dealt with two of these the users believed was the smd and it turned out it was their solder jobs and they both had redone them and were sure the smd was the problem.

There is a better chance if your pcb was in the first batch of a smd issue but should be very little on the second batch.

RJ

[caretaker]

I cleaned the PCB off with Alcohol and noticed then pin 15 is bent into pin 14 on the Network chip, is it supposed to be like that? I will put a fine type in my solder station and try reworking the joints that are blob like and try to clean up the mess I made on the network chip. The cable I used is good because I plug my good etherdongle into it and it worked.

[RJ]

Yes this can happen pretty easy using solder wick on the small pins. if the wick at the ends away from where you are heating cools too much when you move the wick the pin is stuck to the wick and does that. It is a real delicate trick but can be mastered with patience and steady hands.

RJ

[caretaker]

UPDATE: Straightened the bent pin and retouch all solder joints using a flux pen, also retouched pins on net the one side of network chip where pin was bent and tested without success. So as of this point I am throwing it into the broken box and moving on to other things as I am at the end of my capabilities with this board.