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Topic: Anyone know where to buy this part: MBR4045WT (Read 973 times) previous topic - next topic

TheDanishViking

Dec 07, 2015, 08:37 pm Last Edit: Dec 07, 2015, 08:43 pm by TheDanishViking
My parents caravan's transformer was beginning to say a strange noise and when i looked at it I found this part fried. I've tried to search the Internet but with no luck,I was hoping that someone out there knew where to get one.

I've attached a picture of it, it would have three legs but this one is broken.

Thanks

Paul_KD7HB

You have obviously never used Google to source an electronic component. I found quite a few sources for the device as well as data sheets.

Generally when solid state devices overheat, they are not the cause of the problem, but the result. Just replacing this device without determining the cause of the failure and fixing that will result in another fried part.

Paul

Wawa

It's a double diode with common cathodes.
Two 20A/45volt schottky diodes in one case.
Should be able to get from the big part suppliers.
I use RS components for most of my parts.
Leo..

TheDanishViking

Generally when solid state devices overheat, they are not the cause of the problem, but the result. Just replacing this device without determining the cause of the failure and fixing that will result in another fried part.

Paul
What could be the cause?

It's a double diode with common cathodes.
Two 20A/45volt schottky diodes in one case.
Should be able to get from the big part suppliers.
I use RS components for most of my parts.
Leo..
Where can i buy one, or just another part with the same capabilities?

Thanks

Paul_KD7HB

#4
Dec 07, 2015, 09:19 pm Last Edit: Dec 07, 2015, 10:08 pm by Paul_KD7HB
I see now that none of the obvious sources have any in stock. The device is obsolete, so you will have to match it's specifications to another device, or make a replacement using two individual diodes.

If your "transformer" is what we call call a "converter" used to convert the mains AC voltage to 12 volts to charge a battery and power the lights, etc. in your caravan, my 5th wheel trailer, then you will find it cheaper to just replace the "transformer". I have had to buy three replacement converters for my trailer before I got one that ran for more that a few months. They are all made in China, no schematics available. No way to get factory repair for less than a new unit.

Paul

DrAzzy

What could be the cause?

Where can i buy one, or just another part with the same capabilities?

Thanks
Look for schottky diodes, rated at least 20A and at least 45V, two of them - or for a package with two diodes in one package. You will have a great many options.

I usually use the Digikey catalog for finding parts by criteria like that - they've got excellent filtering options. Mouser also does.
ATTinyCore for x4/x5/x61/x7/x8/x41/1634/828/x313 megaTinyCore for the megaavr ATtinies - Board Manager:
http://drazzy.com/package_drazzy.com_index.json
ATtiny breakouts, mosfets, awesome prototyping board in my store http://tindie.com/stores/DrAzzy

Wawa

First hit (of the many).
http://nz.rs-online.com/web/p/rectifier-schottky-diodes/0301259/
Leo..


Paul_KD7HB

I failed to reply to the OP about why the dead dual diode device is not the failure, but is the result.

Solid state devices fail because the junction cannot dissipate the heat generated in the junction. Sometime that is immediate and sometimes it takes a while. The junction in the silicon, or other material is Very, very small. Your diode device shows melted and burned plastic. It was very hot for an extended time. Then the junction opened up and the device died.

The cause of the heat was excessive current through the device caused by another component. That component may be directly attached to the diode via the circuit board, or may be a component further away, causing a cascade of failure.  So, at least one other device on the board is dead.

Without a schematic to follow the paths to and from the diode, you cannot possible repair the "transformer", unless you replace all devices on the circuit board.

Wawa

Not so long ago I replaced a diode like that in a switch-mode battery charger.
It had failed from overheating, because the battery it was connected to was bad.
After replacing the diode, the supply worked as normal.
Leo..

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