This is from a crane cams ignition my cousin gave me.
Can this be fixed?

 

If any of the chips themselves are damaged, then no.

If its just the wire trace on the PCB, and its only a single or dual layer board, then you can remove the insulation on both sides of the burn, and solder in a wire to bridge it. Depending on what components are on each side of the line, the length and size of the wire could have adverse effects on operation.

So, its really anyone's best guess as to whether or not it can be fixed. Try it and find out is about all I can say.

 

Advice above is right on target. Scrape, tin, solder bridge wire. I do it all the time... We've even fixed some flight boards that way, then covered it with "non clear" conformal coating... but don't tell the QA guys...

The real question is you made a fuse, you will need to know why...

 

Does this repair look even half way right?

 

I would run a wire across that instead of just solder.

 

Yeah I tried it like that with just the solder but it still doesn't work so something on the other side is fried as well.Is there any way to test each piece.Visually it all looks good no signs of heat at all.

Here is a pic of after i sanded it clean and soldered in a wire like you said.I may hook it up and try in one more time.with the wire in.
whoa I need to resize this pic.here it is.


here is a pic of the other side



Modified by Dmc1 at 3:38 PM 2/21/2006

 

Try and figure out what that wire connects to.

If it goes to an IC tell me the pin number and IC info.

Maybe take a picture of the top of the board and point to the general area of the burnt trace.

 

I don't know how I missed this.I took it to radio shack to aske the guy what the name of the black thing that looks like a ignition coil from a car.The radio shack guy said it's actually called a power transformer and mine happens to be burnt to a crisp.If anybody can help me find somewhere to order a new on I'd appriciate it.
the part number on the side of it is 10499E




I bought a desoldering iron to.I'm gonna practice on a old circuit board first until I get comfortable then I'll try my hand at fixing this thing.

 

Magnetics are typically an OEM only item. I have never been able to get replacements for most commercial board magnetics. If you can, rewind it, but good luck with the task.

Care, precision, and patience. Match the gage of wire number of turns, and interlayer insulation.

However if the primary magnetics are fried, usually the silicon power switch went first. That is the transistor, FET or IGBT that controls the power flow (switching) to that power transformer.

 

Ok thanks for the help Big Moose. I'll try to find one because I know I won't be able to rewind it right. and i'll check the switch to.I may just buy a new one.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Dmc1 &raquo;</TD></TR><TR><TD CLASS="quote">Ok thanks for the help Big Moose. I'll try to find one because I know I won't be able to rewind it right. and i'll check the switch to.I may just buy a new one.</TD></TR></TABLE>
Why wouldn't you be able to rewind it? They even sell the wire at radioshack. Just count the number of turns that it takes to remove the wire.

Its hard to tell but how do you know the inductor is burnt? From your picture that looks like a black coating over the wires. What burns inductors is DC current. Maybe the IC controlling the switching is putting out a DC voltage, or one of those transistors is stuck high. You can test most of this with a voltmeter. Can you get the numbers off the transistors. One of those I bet is a diode.

Depending on the switching device the actual inductance value may be insignificant. So if your off a little it might not be so bad.

 

I found somthing else thats burnt as well.I don't know what it is though.I have no experiance working with circuit boards.It looks like it connects neg power to the transformer.



what could have caused this?

 

That's a 70 amp MOSFET. RFP70N06 is the #. Try http://www.mouser.com or http://www.digikey.com for a replacement. You might have a short elsewhere, or a localized component failure.

 

Your "transformer" is being used as an inductor. There are only two connections all the rest are shorted. Which if you can figure out the value makes it easier to replace if its burnt.

Are you sure your inductor is burnt?

My suggestion would be to replace that transistor. Then limit the current the crane ignition is able to draw. Then us a DMM set Hz, then check the gate of the transistor to see if it is switching. The gate is the real small trace going to the transistor.

This is a boost convertor google it if you want to see the basic operation.

 

No I'm not 100% sure the inductor is burnt.It just looks like it's got hot.but none the leads coming from it to the circuit board look burnt though.

So it may be fine.Could that switch have went bad and stuck open? and then cause the short on the board&gt;

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Dmc1 &raquo;</TD></TR><TR><TD CLASS="quote">what could have caused this?</TD></TR></TABLE>

Classic failure when the FET looses its ability to dissipate heat. Likely due to age and the degradation of the heat sink. That degradation is due to the heat sink grease drying out, dust, dirt and lint in cooling fins (if you have a finned system.) Also not to be neglected is the design could have been playing close to the SOA or safe operating area of the FET. Just plain age. Silicon power devices can go bad due to the just a little bit of overshoot with each cycle. Thou it is not 100% a correct analogy, think of it as a high cycle fatigue stress fracture of a fastener in a mechanical system with vibration.

Also there could be a failure anywhere in the control circuit of your switched mode power supply. If the FET is left ON past the saturation time of the inductor, it's impedance goes to zip and you have an effective direct short. If I was betting, first the FET just bit the farm, then the control circuit hiccuped.

Your transformer is really just an inductor, as the gent said above. That increases your chances of a successful rewind if the turns are shorted.

Good luck, keep at it!

 

Thanks again man.I'm staying with it this is good experiance for me even if I don't manage to fix it.I'd like to learn how to chip ecu's so this is good soldering on a board that I don't have much to lose with.

 

I have also seen the IC controling the switch stop working. This puts a contant dc voltage to the gate. Which in turn leaves the transistor on. Which then usually burns the inductor and transistor.

Replace the transistor and check to see if its switching.

 

ok I had to order a new transistor so after I get it and replace it I'll test it out.
What is an IC?

 

IC= Integrated Circuit

An IC has many circuits contained in one chip. Follow the small trace back it probably goes to a resistor and then to an IC.