I'm trying to fix a lighsaber - Page 1
Forum section: electronics / repair

author: Njackste
author_rank: Contributor
timestamp: October 24, 2021, 11:39:23 am
content: I have a lightsaber called the tiny giant and it stopped working so I had to take it apart.I removed 3 hex screws but there are these gold things that I can't get open.Can anybody help mehttp://imgur.com/a/56abGQGhttp://imgur.com/a/ZxyHGsU

author: Gyro
author_rank: Super Contributor
timestamp: October 24, 2021, 04:36:04 pm
content: The Force is weak with this one!

author: lunacyworks
author_rank: Contributor
timestamp: October 24, 2021, 05:03:08 pm
content: Looks like those might be yellow leds poking thru the side. It looks like that bolt holds the board and pulls the dc power socket and leds towards the side of the case. Gently push the board away from the side where the lights and power socket are on. Then once the led and socket clear the side of the case you should be able to pull he board out.

author: Njackste
author_rank: Contributor
timestamp: October 24, 2021, 08:33:59 pm
content: Thanks for the help that worked.On the pcb there is some capacitors in short circuit (C4, c5, c7, c8) and also the battery pads make continuityOn U1 the two pins on the bottom left have continuity with each other and with the top middle pin could this be a broken voltage regulator that caused thisBtw the issue was caused by overvolting

author: Njackste
author_rank: Contributor
timestamp: October 24, 2021, 08:35:51 pm
content: https://imgur.com/a/htTWObY

author: Whales
author_rank: Super Contributor
timestamp: October 25, 2021, 12:33:48 am
content: Yep sounds like shorted ICs. The capacitors themselves are unlikely to have gone short (unless you went for a very large over-volt, but then I'd probably see smoke marks & debris in those images).Desoldering and resoldering those SMD ICs might be a bit of a pain. It's probably easier (and safer) to gently cut the power traces between parts and then measure the power rails again to find shorts. Once the repair is over: bridge the cut traces with a small bit of wire and solder.EDIT: or hookup power via a current limited power supply, pour alcohol on the board and find where it dries the fastest. That might however misleadingly blame the voltage regulator when another IC could be shorted instead (over-loading the regulator).

author: fzabkar
author_rank: Super Contributor
timestamp: October 25, 2021, 01:02:36 am
content: Can you tell us the markings on the ICs?ISTM that U5 is first in the firing line. It looks like it might be a linear regulator.U1 looks like a uC, so if one of its GPIOs is shorted to ground (C4), then that would be a bad sign.Is one of the brass stand-offs shorting the copper trace at U4-8?

author: Njackste
author_rank: Contributor
timestamp: October 25, 2021, 01:25:44 am
content: Thanks for the help.It's not the standoffs for sure.On U1 these pins have continuityhttps://imgur.com/a/htTWObYC4 does short circuitI could be u5 I'm not sureWill I try desoldering it? Only problem is that I don't have a hot sir station only an ironAny suggestions

author: rfclown
author_rank: Frequent Contributor
timestamp: October 25, 2021, 01:45:18 am
content: I sometimes use a soldering iron tip that will bridge all the pins on one side. Heat one side and gently pry the IC up to free one side. Sometimes I'll use a dental pick, pushing it under the IC so that the part moves once some pins are free. The soldered leads on the other side have to bend to do this. Then remove the part completely by doing the same on the other side. Try not to bend the part up too much, because you have to bend the pins back. The pins can break off if bent too much back and forth. But I've seldom had that happen.

author: Njackste
author_rank: Contributor
timestamp: October 25, 2021, 01:46:44 am
content: Thanks I'll try that

author: Njackste
author_rank: Contributor
timestamp: October 25, 2021, 01:24:38 pm
content: I desoldered U5 and now the short is gone.This is the chiphttps://www.googleadservices.com/pagead/aclk?sa=L&ai=DChcSEwjr4pSay-XzAhWX3VEKHVV6DnAYABAOGgJ3cw&ohost=www.google.com&cid=CAESQeD2yPH_CeBWb7fkn0NqM4Mw3ytA9JXVeVt3toLUN7PNRBE0G1r-OmO11jM1dm0U2q1Q4x4GMjQRFn5uttbkh3Uw&sig=AOD64_0de92mI4SWsFRUOL-ANd9F-fbchQ&ctype=70&q=&ved=2ahUKEwiVro2ay-XzAhWxhv0HHfDcB4wQwg96BAgBEBU&adurl=But I want to buy the chip from my local electronics shop and they don't have the exact component but will this workhttps://ie.rs-online.com/web/p/battery-management/7328730Also could anything else be broken there is no shorts but how can I check if anything else is gone.