Laptop Blown fuse replacement - Page 1
Forum section: electronics / repair

author: chegueva01
author_rank: Contributor
timestamp: July 12, 2020, 12:14:13 pm
content: Hello guys.I have a sony Vaio that has a backlight issue , i found a fuse ( polyswitch 1A / 32V ) on the motherboard side being blown , so i used a wire to jumper to see if it would work and it did. ( there was a short in the lcd screen)So my question now :Do i need exact replacement for this fuse or can i use another normal fuse or even resistor ( low ohms like 5 or something) ?LOoking forward to your answers. Cheerz

author: wraper
author_rank: Unknown
timestamp: July 12, 2020, 12:29:48 pm
content: You can use usual fuse instead of polyfuse. If you try to use 5 ohm resistor, you will have burned resistor and burned PCB.

author: chegueva01
author_rank: Contributor
timestamp: July 12, 2020, 12:33:29 pm
content: Quote from: wraper on July 12, 2020, 12:29:48 pmI was watching a guy on youtube replacing a fuse with resistor ( 5 ohm) , that's why am asking if that's possibleThe youtuber is Sorin ( Electronics repair school) .https://youtu.be/wnVsuZQfJDI

author: Haenk
author_rank: Super Contributor
timestamp: July 12, 2020, 12:38:29 pm
content: A fuse is there for a reason - so always replace with a fuse.

author: wraper
author_rank: Unknown
timestamp: July 12, 2020, 12:46:39 pm
content: Quote from: chegueva01 on July 12, 2020, 12:33:29 pmIt's dumb. If there is say 0.5A current, it's 1.25W dissipated from this resistor. If current rises to 1A, it becomes 5W. Also instead of simply breaking the circuit, it will overheat and burn the PCB, pads will delaminate.

author: chegueva01
author_rank: Contributor
timestamp: July 12, 2020, 12:49:43 pm
content: Quote from: wraper on July 12, 2020, 12:46:39 pmYe makes sense , he probably used that Resistor then as a wire cause it has low ohms. and still that's a bad idea i reckon. so i'll get myself a normal fuse from a broken screen with same parameters.

author: wraper
author_rank: Unknown
timestamp: July 12, 2020, 12:56:03 pm
content: Quote from: chegueva01 on July 12, 2020, 12:49:43 pm4.7 ohm is has way higher resistance than 1A polyfuse. Not to say in that video it was a usual fuse, not polyfuse and had resistance in range of tens of milliohms maximum.

author: chegueva01
author_rank: Contributor
timestamp: July 12, 2020, 01:11:52 pm
content: Quote from: wraper on July 12, 2020, 12:56:03 pmMaybe it was a 1.5A or 2A Fuse , it's not a polyswitch one. cause it's a different laptop than mine.

author: wraper
author_rank: Unknown
timestamp: July 12, 2020, 01:27:01 pm
content: Quote from: chegueva01 on July 12, 2020, 01:11:52 pmThen it's even worse substitute.

author: chegueva01
author_rank: Contributor
timestamp: July 12, 2020, 01:30:12 pm
content: Quote from: wraper on July 12, 2020, 01:27:01 pmI said maybe so i have actually no idea lol. i'll just grab me a normal fuse cause i can't get my hands on polyswitch one and that's it. no resistor.Thanks mate , i appreciate your help

author: wraper
author_rank: Unknown
timestamp: July 12, 2020, 01:43:48 pm
content: Quote from: chegueva01 on July 12, 2020, 01:30:12 pmIf it had 1206 size, then N marking usually means 2A current rating.

author: aqibi2000
author_rank: Regular Contributor
timestamp: July 12, 2020, 10:14:37 pm
content: Near thE LVDS socket on the LCD panel’s driver board there is also a fuse therefore technically you could leave your jumper intact so long as your ribbon cable’s integrity is not at risk

author: fzabkar
author_rank: Super Contributor
timestamp: July 12, 2020, 11:55:08 pm
content: If you have an old scrap motherboard, you will usually find a 1A, or greater, polyswitch near the USB connectors.

author: wraper
author_rank: Unknown
timestamp: July 13, 2020, 12:18:37 am
content: Quote from: fzabkar on July 12, 2020, 11:55:08 pmYou should not use those. They are rated for 6V or 9V in the best case.

author: chegueva01
author_rank: Contributor
timestamp: July 13, 2020, 12:03:39 pm
content: Quote from: aqibi2000 on July 12, 2020, 10:14:37 pmThat's true , there is another fuse int the lcd screen. so i should just leave it like this then.

author: flolic
author_rank: Frequent Contributor
timestamp: July 13, 2020, 03:24:45 pm
content: Yes, and if your laptop eventually burn down the house because of short in the display cable, remember this thread.

author: wraper
author_rank: Unknown
timestamp: July 13, 2020, 03:31:16 pm
content: Quote from: flolic on July 13, 2020, 03:24:45 pmI doubt this will burn down the house but PCB may receive some irreparable damage.

author: chegueva01
author_rank: Contributor
timestamp: July 13, 2020, 05:21:35 pm
content: Quote from: flolic on July 13, 2020, 03:24:45 pmwhy ? isn't the fuse job to avoid something like that from happening?

author: chegueva01
author_rank: Contributor
timestamp: July 13, 2020, 05:26:37 pm
content: Just to update: the ribbon cable is fine cause i tried another screeen and backlight is back and it worked without any issues.

author: wraper
author_rank: Unknown
timestamp: July 13, 2020, 05:46:00 pm
content: Quote from: chegueva01 on July 13, 2020, 05:26:37 pmIt's fine now but may short later. Or say some moisture may get onto display connector on motherboard (happens quite often).

author: chegueva01
author_rank: Contributor
timestamp: July 13, 2020, 07:04:00 pm
content: Quote from: wraper on July 13, 2020, 05:46:00 pmYe makes sense. i'll just follow your advice and replace the fuse, its no rocket science i guess .