Rockbox Chunk not charging - simple repair?

[armandine2]

I re-acquainted myself with my faulty Rockbox Chunk charging fault, over the weekend.

..the battery cells will charge directly from an external supply and the blue-tooth speaker does play ok.

...the battery does not charge from its own usb port - although a status LED will flash to show "willing".

Off the charger the status LED(s) don't go out - I suspect a short.

[armandine2]

No progress on the fault, as yet.

I did though google some of the components:

TP A3118 - D class amp
4409 - P channel mosfet
SS34 - Schottky diode
25L 1606E - flash memory


The last item I have, a little rashly  , just saved with my unmodded CH341A usb to serial interface.

[armandine2]

... the mosfet should be fairly easy to remove, test and replace if necessary.

[perieanuo]

hi, omho you're not looking to charging circuitry, but to battery load.
maybe the charger IC is the squared one on the left side in the photo?

[armandine2]

Yes, I don't think the mosfet will be at fault - as you say it appears as a charging fault.

I see connected to the 5VDC input an IC labelled (U10):

ACTIVE
2803QJ
JF511

[perieanuo]

maybe the simply method is to buy some battery charger and implant it inside the box, maybe with a separate connector for the new charger, and isolate somehow the existing charger on the board, ideally not to use the speaker when in charge.
otherwise, need to identify the charger ic and dig around, but i wasn't lucky to identify it from your codes, maybe it's a bq one, maybe another...

[armandine2]

I just found this link

https://www.digikey.in/htmldatasheets/production/1966131/0/0/1/act2803-demo-board.html

https://www.digikey.com.mx/htmldatasheets/production/1962225/0/0/1/ACT2803.pdf



might be a fun board to get 

[edited to add schematic - and another ACT2803 link]

[MathWizard]

So does it also play when connected to USB, and just not charge ? What voltage is the separate supply ?

If you are lucky, the charging doesn't get control by some MCU with a problem. But it's not that hard to get power rail IC's and charger IC, etc.

[armandine2]

So does it also play when connected to USB, and just not charge ? What voltage is the separate supply ?

If you are lucky, the charging doesn't get control by some MCU with a problem. But it's not that hard to get power rail IC's and charger IC, etc.

I have not tried (yet) to charge and play at the same time. Not sure what that would prove?

Not sure what you mean by "separate supply". All I have done is play the device with its batteries. These are the original nominal 3.6V ones, so two of them in series (as drawn) is 7.2V. And as I have a bench power supply I can charge them in series through their connector when disconnected from the pcb at 7.2V.

There is a charging fault - the 5VDC usb input does not charge the batteries - but the status LEDs blink.
There isn't a play fault - other than when switched off the device does not turn off the status LEDs. But they go out when the battery to pcb connector is disconnected. And the status LEDs come on again only when the connector is reconnected and switched on.