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Electronics => Repair => Topic started by: Njackste on October 24, 2021, 11:39:23 am

Title: I'm trying to fix a lighsaber
Post by: Njackste on October 24, 2021, 11:39:23 am

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 me

http://imgur.com/a/56abGQG (http://imgur.com/a/56abGQG)
http://imgur.com/a/ZxyHGsU (http://imgur.com/a/ZxyHGsU)

Title: Re: I'm trying to fix a lighsaber
Post by: Gyro on October 24, 2021, 04:36:04 pm

The Force is weak with this one!   ;D

Title: Re: I'm trying to fix a lighsaber
Post by: lunacyworks on October 24, 2021, 05:03:08 pm

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.

Title: Re: I'm trying to fix a lighsaber
Post by: Njackste on October 24, 2021, 08:33:59 pm

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 continuity

On 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 this

Btw the issue was caused by overvolting

Title: Re: I'm trying to fix a lighsaber
Post by: Njackste on October 24, 2021, 08:35:51 pm

https://imgur.com/a/htTWObY

Title: Re: I'm trying to fix a lighsaber
Post by: Whales on October 25, 2021, 12:33:48 am

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).

Title: Re: I'm trying to fix a lighsaber
Post by: fzabkar on October 25, 2021, 01:02:36 am

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?

Title: Re: I'm trying to fix a lighsaber
Post by: Njackste on October 25, 2021, 01:25:44 am

Thanks for the help.

It's not the standoffs for sure.

On U1 these pins have continuity https://imgur.com/a/htTWObY

C4 does short circuit

I could be u5 I'm not sure

Will I try desoldering it? Only problem is that I don't have a hot sir station only an iron

Any suggestions

Title: Re: I'm trying to fix a lighsaber
Post by: rfclown on October 25, 2021, 01:45:18 am

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.

Title: Re: I'm trying to fix a lighsaber
Post by: Njackste on October 25, 2021, 01:46:44 am

Thanks I'll try that

Title: Re: I'm trying to fix a lighsaber
Post by: Njackste on October 25, 2021, 01:24:38 pm

I desoldered U5 and now the short is gone.

This is the chip https://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= (https://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 work https://ie.rs-online.com/web/p/battery-management/7328730 (https://ie.rs-online.com/web/p/battery-management/7328730)

Also could anything else be broken there is no shorts but how can I check if anything else is gone.