How to read SM fuses.

[Nigel Goodwin]

I've got a Sony 30 inch LCD TV for repair, and there's a surface mount fuse blown on the inverter board - it's marked '15' on it's body, and placing an ammeter across it reads about 70mA with the set working. There's also 8 more SM fuses (one for each tube inverter), and these are marked '40'.

Does anyone know what values these are? - a quick google didn't find any with similar numbers, only letters or the actual value in amps.

As the inverter is part of the LCD panel there's nothing in the manual, and Sony wouldn't be able to help, you're supposed to replace the entire LCD screen.

 

[Hero999]

I hate unlabelled SMT parts, especially those little ceramic capacitors, more often than not you can guess the value but there are occasions when it's not that simple.

Sorry, I can't help you here, you should probably replace it with a 100mA fuse but I'm aware you already know that.

 

[transistor495]

Try this pdf file if you can sort it out. It tells that 15 means 15A!

So 40 should be a 40A fuse!

 

[Nigel Goodwin]

Try this pdf file if you can sort it out. It tells that 15 means 15A!

So 40 should be a 40A fuse!

Thanks for the try, but it's obviously not that - as I said the '15' one has 70mA flowing through it during use, and the eight '40' ones share the current (at 24V) for the backlight inverters (and it doesn't need 320A).

 

[transistor495]

Oops!..I was thinking what kind of panel it was

Normally it won't go more than 2A right(sm fuses in LCD panels)?

 

[Hero999]

The fuses marked 15 are more likely to be 150mA and the ones marked 40, 400mA but without the schematic or datasheet it's just guesswork.

 

[Nigel Goodwin]

The fuses marked 15 are more likely to be 150mA and the ones marked 40, 400mA but without the schematic or datasheet it's just guesswork.

That's one thing I was wondering - but (like you) it's pure guess work.

I've got more confidence in the numbering system used on small soldered in fuses (circuit protectors, the ones that look like small two legged transistors)

F10 or N10 400mA
F15 or N15 600mA
F20 or N20 800mA

and so on.

I was hoping someone could confirm this?.

 

[Hero999]

I've got more confidence in the numbering system used on small soldered in fuses (circuit protectors, the ones that look like small two legged transistors)

F10 or N10 400mA
F15 or N15 600mA
F20 or N20 800mA

and so on.

I didn't know about that convention.

It sounds like a very silly way of labelling fuses, the resistor/capacitor convention of using the last digit as a multiplier would make more sense.

 

[Nigel Goodwin]

I didn't know about that convention.

It sounds like a very silly way of labelling fuses, the resistor/capacitor convention of using the last digit as a multiplier would make more sense.

It took me a LONG time to find out what the numbers actually meant on circuit protectors - we used to just change them for one the same, with no idea what the values were.