Electronic Liquid Display board repair!

[crised]

Hello,

I have an electronic display of a plastic machine that does turns on. The screen consists of two SHARP boards, LJ51AU27 and a smaller one placed on top PS515.

The problem apparently is on the PS515. Both fuses were blown. I replace the fuses with thin wires, but two "transistors" K138 (similar than the one in the pictures), gets really hots.

I can't replace the transistors, since there is no information about then!. There is no information about anything on this card. If any please help!

 

[Sceadwian]

If you can't find it via Google or from supplier requests then there is likely little that the users here can do unless they've used the exactly model and serial number of unit you have.

 

[crised]

I understand. But I imagine that this circuit for an electronic liquid display may be similar with other ones. I believe those "transistors" are used in order to make the little transformer work, making a frecuency.

 

[Sceadwian]

Designs for even similar devices can vary dramatically between makers. Also there may be nothing wrong with those transistors, it could be something else damaged elsewhere in the circuit that's causing them to overheat. The transistors may also under normal operation get that hot. Without a schematic of the board you really don't have anything to work with, especially considering that the fuses were blown there is practically no way to tell what else was damaged, also replacing a fuse with a piece of wire is a really bad idea you should always replace them with fuses of the same type. If they continue to blow then the device is damaged.

 

[crised]

The schematics? Where can I get them? No results in google...

I will have the same board new, will that help to repair this one?

 

[crised]

Could those transistors be darlington?

 

[Sceadwian]

Could be. Might not even be a transistor, could be an SCR, could be a diode array. Without a schematic you'll have to reverse engineer the circuit to figure out what it is.

 

[crised]

Will the attached datasheet help? I got it from Sharp.

 

[Sceadwian]

Nope, no help at all.