Macbook A1466 bad backlight fuse, keeps blowing

[Blacktek]

Anyone knows why this fuse keeps blowing? i dont have the boardview/schematic for this model 820-3447-A

[BCConnectionLLC]

Re: Macbook A1466 bad backlight fuse, keeps blowing

Well could be a few things. Without you checking anything the most common issue is LVDS cable gets internally shorted.
You should probably check both pads on the Fuse and look for a GND Short.

Was this a water damaged board?

[Blacktek]

Re: Macbook A1466 bad backlight fuse, keeps blowing

Well could be a few things. Without you checking anything the most common issue is LVDS cable gets internally shorted.
You should probably check both pads on the Fuse and look for a GND Short.

Was this a water damaged board?

Well LVDS cable seems fine, i get no continuity to ground on both pads on the fuse, in diode mode it works its way up to OL. by any chance do you have this schematic and brdview? its hard without it.

[stj]

Re: Macbook A1466 bad backlight fuse, keeps blowing

is it led, or ccfl backlit?

[Blacktek]

Re: Macbook A1466 bad backlight fuse, keeps blowing

is it led, or ccfl backlit?

led

[stj]

Re: Macbook A1466 bad backlight fuse, keeps blowing

could be a blown controller on the panel.

they usually use a single chip containing the led controller and a bunch of fets to drive the led strip.

[Blacktek]

Re: Macbook A1466 bad backlight fuse, keeps blowing

It could be but again without a schematic its like a needle in a haystack...Do you have the schematics?

[Blacktek]

Re: Macbook A1466 bad backlight fuse, keeps blowing

could be a blown controller on the panel.

they usually use a single chip containing the led controller and a bunch of fets to drive the led strip.

It could be but again without a schematic its like a needle in a haystack...Do you have the schematics?

[stj]

Re: Macbook A1466 bad backlight fuse, keeps blowing

no, i dont think panel schematics exist.
look at the board on the back of the panel, if the chip is bad it will probably have a burn-mark on it.
look for a small square chip near the led cable.

[BCConnectionLLC]

Re: Macbook A1466 bad backlight fuse, keeps blowing

So with the panel connected at the LVDS do you get any GND continuty on the LED BKLT pins? Usually its 2 pin that share a fairly large pad towards one end of the LVDS connector.

You may not have a short on the other side of the LED Driver chip but possibly after the chip that shorts it when it turns on and draws too much power.

Here is the schematic. Dont have the BRD view currently

[BCConnectionLLC]

Re: Macbook A1466 bad backlight fuse, keeps blowing

So yes looking at the schematic there is a FET that closes when the LCD panel is off or the computer isnt on so measuring for a short at the fuse becomes useless.

Need to meter it at the LVDS connector

[Blacktek]

Re: Macbook A1466 bad backlight fuse, keeps blowing

So with the panel connected at the LVDS do you get any GND continuty on the LED BKLT pins? Usually its 2 pin that share a fairly large pad towards one end of the LVDS connector.

You may not have a short on the other side of the LED Driver chip but possibly after the chip that shorts it when it turns on and draws too much power.

Here is the schematic. Dont have the BRD view currently

thanks guys for the help, i ended up buying another board. would be nice if you could repost the file, missed it. for future reference

[dellxps15]

Re: Macbook A1466 bad backlight fuse, keeps blowing

new board for a fuse blown?

remove fuse and check if is from the lvds connector side (99.9% is that way)

then remove lvds cable and lvds ic and see if still shorted.

[BCConnectionLLC]

Re: Macbook A1466 bad backlight fuse, keeps blowing



I agree though. This is a simple fix. No need to buy a new board.

[mmmilo]

Re: Macbook A1466 bad backlight fuse, keeps blowing

Though its an old thread i dont want to open a new one.

I got the same problem with my 820-3209, replaced the fuse ad it blew again, checked lcd bklt en and it is 0 volts. smc_lid is 3.4 volt.

My LVDS looks bad, would u replace it first or keep troubleshooting? And if u keep troubleshoot, than where do i continue? without the fuse i cant mesure voltage right?
Its prety hard to finda sjhort to ground, checked the whole section on the top of my board, where the lvds connector is located.

I`m new in this , watched and read mostly from the famous luis rossman, but still have to say it looks easier as it is- i mean trouble shooting.

ty