Xantrax truecharge 2 60 repair help

[sup8pdct]

Have above that doesn't charge. I figure processor is ok as it displays the last settings when turned on.
There is damage to components on an area on the board that i need help in IDing.
1st pic shows a parallel pair of resistors of which i assume is a very low value.  Maybe 1 or.1?
2nd pic shows a another resistor which has 1 digit damaged. I cannot tell if it is a 0 or an 8. ie 20 or 28 ohm?
Also did up a schematic of the area which i hope will help.
No joy from xantrax re schematic.  They want unit + $$$$ to fix it

Any help or suggestions are welcome.

James

[Armadillo]

unknown resistor = 1v/60A = 0.0333333 ohm X 2 [in parallel]

for the 20 or 28, can't you ohm meter it.? But there is no 28 ohm in 5% type resistors.

Attached reference but check your footprint.

[sup8pdct]

Tried to ohm meter it. Is burnt so is now open circuit.

I thought numbers on parallel resistors were a 0 or 1 .would never thought of a 393 .   Thank you

James

[Armadillo]

393 is just the smd marking by Vishay, other manufacturer may have their own marking... like TE marking is 3002 as attached.

If your footprint allows, maybe you can opt for bigger watt resistor instead of sticking to 1W.

Enquire the parts by value, watt, footprint.... their parts numbers are different.

What causes the sense resistors to burn? I trust you have those answered!

[sup8pdct]

I believe the 2sk mosfet is shorted. I was told a dead gecko came out when fuse cover was removed. I cannot see how a gecko can get in. unit.

james

[sup8pdct]

I had another look at unknown resistor with different lighting and it looks like a 1R0.
What does everyone else think?
This circuit is a secondary power supply for (I am guessing) the control side of unit.
Another problem is finding a 2SK2608. This cross reference i found http://noel.feld.cvut.cz/hw/st/3650.pdf lists another one that i cannot find either from digikey. 

James

[Armadillo]

I had another look at unknown resistor with different lighting and it looks like a 1R0.
What does everyone else think?
This circuit is a secondary power supply for (I am guessing) the control side of unit.
Another problem is finding a 2SK2608. This cross reference i found http://noel.feld.cvut.cz/hw/st/3650.pdf lists another one that i cannot find either from digikey. 

James

Man! the pads looks like it had suffered immense torture. Are you using a Auto Repair soldering iron? The pads need to be clean up properly.
 
The charger is 60A so it CANNOT be 1R0.
Since you got 3 slots, you can use 0.05 ohm X 3 [in parallel] @ 1 watts each or higher watts depending on your pad footprint. If you use 1R0 X 3, I bet your charger will limit the current at 3A only. [Well, unless the charger is a fake].

There are so many sellers in ebay for the 2SK2608 Toshiba mosfet. Why do you need cross-reference?

[sup8pdct]

To clarify. Here is a pic of whole charger. Area i am trying to fix is the small section circled in red. There is no way this small section can supply 60A, maybe closer to 1A.

So would a parallel pair of resistors at this location be conceivably be 1ohm given such small supply current, small transformer and small heatsink for main switching transistor? I want to try and get them right. Don't want to blow up the processor which i believe this part powers.

I don't wish to touch ebay for components. So many fake parts around.

James

[pubo]

I know this is an old thread, just wondering if you've managed to get this working?

I have one of this unit here with some charred components as well, 60Amp version but the board seem to have slightly different layout.

If anyone would be so kind to share some images, it'll be greatly appreciated. 

[sup8pdct]

No. I dont have any SMD tools. Also dont know resistor value. so it will be a guess'

James

[pubo]

Oh okay. Cheers for the reply. I'm surprised how much changes they've made between the revisions.

Here are some images of mine. I'm guessing the busted IC would be a TOP258PN from its weird 7 pin layout.

Fingers crossed this will fix mine

Maybe it'll be of some help to you.