Ether Dongle Over Heats

[kevinpickett]

Just got 2 Etherdongles in from the latest coop, built the both at the same time.  One works great the other one does not work.  No led light.  The 117v33 gets hot as soon as the unit is plugged in. 

Any place to start looking?  I have double checked my solder joints no cross connects or solder splatter, and correct placement of critical components (pos & neg position).

Pickit finds 32mx chip but will not program it.

Thanks
kevin

[tbone321]

Make sure that none of your chips are in backwards and check the caps as well.  A hot 3.3V reg indicates excessive current draw and could still be a short.  From what coop did you get these boards? 

[kevinpickett]

the board was just purchased of the latest coop. 

It is a short somewhere in the 3.3v circuit or a bad voltage regulator.  Is there a way to test the regulator.  When I removed the regulator my input voltage jumped back up the 8-9v as opposed to the 5-7v that I was getting, so there is a short on the 3.3v side.

[tbone321]

You may want to post a few pics of the board (front and back).  Make sure that they are closups and clear.  Take the shot at a slight angle to minimize glare from the flash.

[Dennis Cherry]

Look real close for any solder shorts. if in doubt put some close up pictures of your board in this thread.

[deplanche]

Double check the voltage regulators too (and post pics of them where you can read the numbers).  If these are installed in the wrong location or you are using the wrong ones it can cause problems, as well as the overheating.

If you have a digital volt meter, you can check the power going into and out of each of them, to see if it is what you are expecting.

[caretaker]

the board was just purchased of the latest coop. 

It is a short somewhere in the 3.3v circuit or a bad voltage regulator.  Is there a way to test the regulator.  When I removed the regulator my input voltage jumped back up the 8-9v as opposed to the 5-7v that I was getting, so there is a short on the 3.3v side.

Yes, with the regulator removed find out the pin out for it (mouser will have it) and apply 5 or 12 volts DC to the input and ground OF the regulator (with it out of the circuit) and see what the voltage is on the output. 

[kevinpickett]

with the regulator installed I get 5.73v at the DC Plug voltage in.  At the 3.3v regulator I get 5.16, 5.15, 2.19volts on the regulator legs.  The regulator gets too hot to touch within 5 secs of plugging the unit in.

With the regulator removed I get 8.5+ volts at the DC Plugin voltage.

kevin

[tbone321]

The regulator appears to be working properly but it won't for long getting that hot. 

[kevinpickett]

Just re soldered all the connections to ensure no cold solder joints, and to verify no bridges.  no change. 

[tbone321]

A cold solder joint will not cause this.  Polarized components in backwards, bridged connections, and components in the wrong location can.  At this point, I believe that except for guesses, there is little more that we can do without some clear closeup pictures of both sides of the board so that fresh eyes can take a look to see if something is wrong.  Sometimes it's really like looking fr a lost set of keys that someone else just walks in and picks right up.  The problem may be obvious but you are just not looking there and it happens to all of us at one time or another.

[kevinpickett]

Photos of front and back of the board that is overheating

[kevinpickett]

Will post better pictures tomorrow.

My luck is running out, the ED that I had working (ED #2) now will not see data coming into it via the magjack (no connection "green" light or "Amber" transmit).  It was working, but than started to act strange and now not at all. When I hook up a friends ED it works fine,  so I know the issue is in the ED,s them self.  It appears to be the pic32MX SMD.  I hold it up to the light and I see some legs connecting with each other cant tell if its in the board itself or what, but it doesn't look like a solder bridge, looks more like a trace bridge.  I tried to clean up with some flux remover, but that didn't seem to help at all.

I guess I'll have to send ED#2 with the bad SMD connection to RJ or someone with more knowledge than I have to look at it. and probably end up having to send ED#1 with the overheating problem as well, unless someone sees an issue that I overlooked.

What is the procedure for this?  Is there a repair procedure?

Thanks
Kevin

[tbone321]

The problem is that you and others really have to read all the posts in these thread or to ask before attempting to make repairs to these boards.  Many of the things that you may find have already been found and resolved which can make solving the issue for you much easier.  Multiple people reporting the same issue is also a good indicator that there may be an issue with either the board or the manual that may need to be corrected in the next release.  In the case of the bridge that you saw, it may be the one that is supposed to be there and attempting to remove it can damage or destroy the board.  The first step is better pictures so that we can really see what is going on. 

[dpitts]

The problem is that you and others really have to read all the posts in these thread or to ask before attempting to make repairs to these boards.

I was at Kevin's house while he read posts for several hours, so not quite sure how you know he has not read posts. The good news is he is pretty clever and is willing to try different things to troubleshoot his problem.