Acer AL1916 PSU Repair. - Page 1
Forum section: electronics / repair

author: B3nny11
author_rank: Newbie
timestamp: January 26, 2015, 10:57:43 pm
content: Soo, i am quite curious if the psu for this LCD could be repaired. Take a look at the pictures what is going on.At first a thought that a cap blew. But that's not the problem I think. All the caps look good.Any suggestions?Thanks up in advance.BenEdit: Yes when I plug the monitor in a wall socket it gives no life at all.Edit2: The serial for the board is: 715G1492-2Is there a easy way to test the caps? Perhaps with a multimeter?

author: Phaedrus
author_rank: Frequent Contributor
timestamp: January 26, 2015, 11:47:02 pm
content: I used to have an AL1916. Decent monitor.What are the failure symptoms? It's quite possible that the power supply caps have failed without visibly bulging/leaking. Replace them all. Also, get some 90% isopropyl and clean all that dust off.

author: B3nny11
author_rank: Newbie
timestamp: January 27, 2015, 12:30:17 am
content: Welp. No idea as said in the edited post, it just wont turn on.The caps, is there a simple way to test them somehow? None of them have visible damage.Fuse is ok. Cleaned the dust (most of it) with compressed air.

author: Phaedrus
author_rank: Frequent Contributor
timestamp: January 27, 2015, 12:35:05 am
content: An ESR meter. Low-ESR PSU filter caps should have 0.1-0.3mOhms ESR, if they read >0.6mOhms they're probably bad.But caps are cheap. Should be able to get Panasonic/Rubycon/NCC replacements for less than $5; there aren't that many on there. Make sure to get ones with a good ripple current rating and 105C temperature rating.

author: Rasz
author_rank: Super Contributor
timestamp: January 27, 2015, 09:38:56 am
content: no life at all = start with fuse, measure all semiconductors (mosfets, diodes) for shorts

author: wraper
author_rank: Unknown
timestamp: January 27, 2015, 01:02:46 pm
content: Did you measure the voltages on the output BTW. Nothing at all?Check if there is voltage on the big capacitor when connected to the mains. If there is check another things on the picture.

author: B3nny11
author_rank: Newbie
timestamp: January 27, 2015, 10:37:44 pm
content: Ou key, will do. Had no time today for it.Will keep you posted.

author: DmitryL
author_rank: Regular Contributor
timestamp: January 27, 2015, 11:26:05 pm
content: Quote from: B3nny11 on January 26, 2015, 10:57:43 pmat first glance capacitirs look ok. Difficult to say without measuring their ESR. It was already suggested that you may need to check if PSU woks at all.Another possible reason: degraded CCFL backlight lamps. Backlight invertor can't deal with it and shutdowns PSU. You can try disconnecting CCFL lamps connectors and see if PSU starts. If PSU works then, you can use external light source (flashlight for example) to shed some light onto the screen and see if there is a picture. It is very difficult to see it without backlight.... replacing CCFL lamps in display module is a torture

author: obiwanjacobi
author_rank: Super Contributor
timestamp: January 28, 2015, 03:43:23 pm
content: Did you unhook the connector to the other board? So are you testing without a load?

author: oldway
author_rank: Super Contributor
timestamp: January 28, 2015, 05:39:33 pm
content: Quote from: Rasz on January 27, 2015, 09:38:56 amAnd do not forget to check if you have the main voltage at the input of the psu.

author: B3nny11
author_rank: Newbie
timestamp: January 28, 2015, 09:09:40 pm
content: Quote from: oldway on January 28, 2015, 05:39:33 pmHaha very funny. Enjoy it while it lasts.

author: B3nny11
author_rank: Newbie
timestamp: January 28, 2015, 09:17:26 pm
content: Quote from: wraper on January 27, 2015, 01:02:46 pmI did measure them a while ago.The main cap voltage kept jumping... I have no profesoinal multimeter, but I did see numbers from 50to300v.So i ordered new caps, all of them.

author: oldway
author_rank: Super Contributor
timestamp: January 28, 2015, 10:46:26 pm
content: QuoteMain power switch with bad contacts ?

author: wraper
author_rank: Unknown
timestamp: January 28, 2015, 10:54:01 pm
content: Probably big electrolytic capacitor dead. And multimeter readings jumps when psu tries to start.

author: B3nny11
author_rank: Newbie
timestamp: January 29, 2015, 12:20:20 am
content: Quote from: oldway on January 28, 2015, 10:46:26 pmThere is no mains switch. ~_~