LED lamp isnt working, but want to try fix it!

[Dylan Lie]

So I've owned this cheap lamp for quite a while now but it suddenly stopped working on me. It has sentimental value so I want to try fix it myself, so please help me! It is a rechargable lamp, so it has a rechargable battery, along with an adaptor cable, and a switch to turn it on/off without having to connect the adaptor. I'm not sure what's wrong with it but I have seen the LED's flash for a split second when I try to plug it in, but it just won't charge and light up like it used to. I've opened it up and haven't spotted any faults in the wires and joints etc, so I'm not sure if it's just the battery.. I'm not very good at electronics but do know my basics in how to connect and solder the components together. I don't remember how to identify the components tho so I've attached pictures of the circuit and the lamp. I'm happy to replace all the components and rewire everything but I don't actually know what the components are precisely... Please give me advice on what I should do and I'll try my best to fix it. Much appreciated guys!

 

[KTW]

I've owned this cheap lamp for quite a while now

More than likely the battery won't take a charge any longer.
You'll need a volt meter to test the output of the charger and the battery voltage.
If the charger is putting out voltage to charge the battery then the battery is toast and you'll need to replace it.

 

[Dylan Lie]

More than likely the battery won't take a charge any longer.
You'll need a volt meter to test the output of the charger and the battery voltage.
If the charger is putting out voltage to charge the battery then the battery is toast and you'll need to replace it.

Do you have any idea which kind of battery I should be getting for this? like voltage, etc. I don't own a volt meter so I'm thinking of just replacing it because that sounds easy enough!

 

[TheMaster]

If it wasn't mishandled or you have no reason to believe that the circuit became damaged then it's probably the battery, which can be replaced. You can perform tests with a multi-meter to determine the exact source of the problem.

 

[KTW]

any idea which kind of battery

That's the tricky part.
The battery has to match the charger and it's probably made in china.
Are there any specs on the light or the charger?

 

[Alec_t]

Looks like the blue/brown wires from the battery have a nick in them where they cross you forefinger?

 

[Audioguru]

The LEDs are all connected in parallel (horrors) so the little battery is probably a single cell Li-Po. The battery is ruined if it has been fully charged for months or has been discharged too low.

The "charger" circuit appears to be too simple and will overcharge a Li-Po battery cell which also ruins it.

 

[tedstruk]

the lights flashing a bit when you plug it in is a good indication that one of the diodes in the main board is shot. you might need to replace it with one of the same size...
if you have a VOM with a diode checker, use it. it will look like a triangle with a bar on one end on the VOM switch that changes from ohms to volts or whatever.

 

[73's de Edd]

This was being a single add on to your LATEST post . . .but since . . . IAN has moved here to unitize all prior replies .

Sir Dylan Lie . . . . .

You didn't quite give totally overall encompassing photos, but I can make out that the LED display panel is divided up into two series LED portions.
The yellow is a common ground connection of the two strings and the white and red lines receive power.
Probably the division is because the battery voltage cant supply a TOTAL, single string of LEDS.

If this unit has been unplugged and dormant for a year or so, the probable cause is the time related internal self draining leakage of the rechargeable battery.

This units little configuration of a " trickle " charger that is being derived from the AC line from an isolative capacitor, just does NOT have the OOOMPH required to get that battery back UP to a present charge level state, such that it will then be receptive of a mere trickle charging level.

PROCEDURAL:

Testing done with NO AC power connected.
Take DVM in hand and set up to read DC voltage, initially at its 50 volt range. Then you can drop on down ranges to get the most accurate reading.
Greatest expectation is for that battery to be a 9 Volt rechargeable, but remote chance of an oddball 6 Volt rating.
Expecting its battery technology family to be either ni cad or ni mh.
Initially examine the battery case to see if any of that info is stamped / marked on it.
If not, proceed in stabbing appropriate meter probes into the two terminals o the battery,I say stab since it appears to have quite a pb/sn oxide layer built up on them.
Do we have any voltage ? . . .or even a trace of a voltage ?
If not . . . .original battery . . . . . KAPUTTTTTT !
Time to take a quick gamble now.
Get a conventional 9 volt battery . . . .get one of Mamma Cass's fine grit emory boards and clean the rechargeable batts soldered connections . . to shiny solder . . . but DON 'T break a wire off !.
Set up your units switches / adjustments to the positions that used to make the unit be turned on and be running solely from battery power.
One eye diverges onto the LEDS panel, the second observes the application of the new conventional 9 V battery to the rechargeable batteries cleaned terminals .
BLUE is positive polarity on the RECHARGEABLE battery and you can confirm polarity from its markings on the new battery.
Make a quick battery connection, just long enough to see . . . .if the LEDs come on ?

IF so . . . are they about the same brightness as they always were being before ?
If not, the next confirmation would be to get assistance of another set of hands, to hold previous DC metering to the rechargeable battery, while the new battery is swung into contact again.
IS the OLD battery loading down the new battery, such that its voltage is seriously being pulled down ?

Gonna stand by to wait for your progress . . . . .

Then the REAL magic can start


73 's de Edd

 

[Ian]

@Dylan Lie - please don't make multiple threads on the same issue, as it really confuses things. I've merged all three threads in to this one - so apologies to members who have had their posts moved.

 

[cjdelphi]

Even without the battery the light should light...

I'm with whoever said the diode is to blame, also is that red safety capacitor good? No shorts?