Harman/Kardon Onyx Bluetooth Speaker - No Power

[fzabkar]

Re: Harman/Kardon Onyx Bluetooth Speaker - No Power

The ISET resistor configures the fast charge current at 820mA. AIUI, the ISET voltage is 2.5V when the IC is fast charging. Therefore a voltage of 0.31V would correspond to a charging current of ...

(0.31V / 2.5V) x 820mA = 102mA

I could be wrong, but that's how I interpret the datasheet.

I don't understand the behaviour of the power LED. That would be driven by the Bluetooth module. ISTM that the module may not be sensing the battery correctly. Perhaps you should check the module's Vcc and BAT pins. I would also measure the voltages at the BAT54C dual diode.

[caphair]

Re: Harman/Kardon Onyx Bluetooth Speaker - No Power

Awesome, curious how you arrived at 102ma?

Also why does the power led slow flash even with charger disconnected if a slow flash means charging, it never fast flashes to indicate low battery either like it's supposed to.

[fzabkar]

Re: Harman/Kardon Onyx Bluetooth Speaker - No Power

The thermistor voltage corresponds to a resistance of 10.4K, which in turn corresponds to a temperature of around 25C.

When the battery voltage reaches 4.20V (or near enough), the charger should go into constant voltage mode and the battery current should then gradually decline until it hits the pre-term setting. IIUC, an ISET voltage of 0.31V corresponds to a charging current of 102mA. That's higher than the pre-term setting of 82mA. AIUI this explains why the battery never stops charging.

ISTM that the battery is old and tired, or maybe it was damaged by overcharging or deep discharge. I would run the speaker on battery power and see how long the battery lasts before it goes flat. If you get reasonable play time out of the battery, then you might be able to extend its useful life by increasing the pre-term current to 100mA, say. However, you would need to modify a resistor value. That said, I don't know if it would safe to muck about with a sick lithium battery.

[caphair]

Re: Harman/Kardon Onyx Bluetooth Speaker - No Power

ISET has .31v and voltage at thermistor is .52v

Also battery is 4.18v does it have to reach 4.2v to stop or close enough? Because I noticed it keeps fluctuating between 4.18 and 4.17v

[fzabkar]

Re: Harman/Kardon Onyx Bluetooth Speaker - No Power

I would measure the voltage at the thermistor and the voltage on the ISET resistor. That should tell us the temperature and the charging current. Charging should stop when the current drops to 80mA.

[caphair]

Re: Harman/Kardon Onyx Bluetooth Speaker - No Power

Scratch that about c309 I was accidentally tracing the grounds to those other components.

[caphair]

Re: Harman/Kardon Onyx Bluetooth Speaker - No Power

Ok I measured the battery and it has 4.2v on it. So is there something wrong with whatever tells the power led the battery is full?

I wonder if it has anything to do with the original problem and the smd cap I replaced because the "power led" line I traced back to c309 which the other end connects to c318 which connects to c317 which goes to the base of q301

Or that could just be for power on led not charge flash. Not sure what to look for next in terms of this

I also noticed power buttonA has 4.1v and power buttonB has 0v even when powered on but in original fault the voltage to B would go high after pressing A. Not sure if related or has any meaning to current issue?

[fzabkar]

Re: Harman/Kardon Onyx Bluetooth Speaker - No Power

Your battery is rated at 2600mAH. My previous calculations suggest that the precharge current for a flat battery is 160mA, the fast charge current is 800mA, and the pre-termination current is 80mA. This means that the charge time for a dead flat battery would be in excess of 3 hours (2600mAH / 800mA = 3.25 hours).

[caphair]

Re: Harman/Kardon Onyx Bluetooth Speaker - No Power

Yes same battery. Before it'd take anywhere from 2-4 hours I believe.

I'll leave it plugged in overnight and see what happens.

I'll run an ammeter through it tomorrow. What should I be looking for?

One thing I noticed is upon first power up with charger disconnected the speaker turns on then quickly shuts off. A few seconds later it powers on fine.

Manual says quick flash means low battery and slow flash means charging.

It's only doing a slow flash when charger plugged in or disconnected.

[Agent24]

Re: Harman/Kardon Onyx Bluetooth Speaker - No Power

How long did it take to charge before?

Is this with the same battery which was measuring 0v before? If it is, perhaps you need a new battery.

You could try putting an ammeter in series with the battery and see what the charge current is.

[caphair]

Re: Harman/Kardon Onyx Bluetooth Speaker - No Power

Thanks man.

So I left this thing charging for three hours. Came home and the power led is still flashing which means low battery/charging. Figured it'd be a solid light by now.

Unplugged charger and it powered on with the battery, so I guess it's charging but takes a while?

I hope there isn't a new issue like the full battery indicator faulty or something lol

[Agent24]

Re: Harman/Kardon Onyx Bluetooth Speaker - No Power

Good point, I didn't think about the grounding\heatsink pad. Sounds like what you did was the best way then.

[caphair]

Re: Harman/Kardon Onyx Bluetooth Speaker - No Power

Left it charging and haven't been home yet for the final declaration that it's 100% fixed lol

What I did was removed old ic with hot air and flux then cleaned and added the tiniest bit of fresh solder on the board contacts, added flux and basically reflowed new ic with hot air. It had a ground plate for heat dissipation underneath so realized hot air would be best method.

[Agent24]

Re: Harman/Kardon Onyx Bluetooth Speaker - No Power

Good to hear

SMD parts are hard at first but once you get the technique they're not so bad. I would probably have used a drag soldering method to install the new chip. I find with SMD a big part is good flux and very little solder.

[caphair]

Re: Harman/Kardon Onyx Bluetooth Speaker - No Power

Update:

Replaced ic charger and the diode and instant 3.20v on output of the ic charger and at battery. Kept measuring and voltage was slowly increasing

That ic was the hardest thing I've ever replaced! Used hot air but still wasn't easy had to apply kapton tape around the near by plastic connectors. Took me a bit but finally got it.

I want to thank you guys tremendously for your help/input. Learned a lot on this one!

[Agent24]

Re: Harman/Kardon Onyx Bluetooth Speaker - No Power

If the battery now measures 0v at its terminals then it's dead. The protection circuitry has likely disconnected the cell(s) for some reason, maybe over-discharge.

I don't think it's fixable, if it is, I don't know how, in either case, the protection circuitry will have disconnected it for a reason - lithium cells are dangerous if over-discharged or over-charged and should not be used afterwards due to explosion\fire risk.

[caphair]

Re: Harman/Kardon Onyx Bluetooth Speaker - No Power

Also, is the battery considered not rechargeable since it gives a 0v reading?

If I wanted to charge the battery with my bench psu how would I go about it?

[caphair]

Re: Harman/Kardon Onyx Bluetooth Speaker - No Power

Ok so bc it's easiest to remove, I removed D300 and plugged charger in, without powering speaker on I took voltage measurements.

The input pin of battery charge ic had 4.67v but now no output at 0v
Also at the contact point of where D300 pin 1 would be there was 4.67v and nothing measured on the other two (as suspected with it removed)

Made me wonder if D300 was shorted and causing output of ic charge to be the low .67v?

Seems like it's needed before charge ic outputs a voltage to the battery

[fzabkar]

Re: Harman/Kardon Onyx Bluetooth Speaker - No Power

I don't know, but I'd change it anyway. It should be cheap enough.

[caphair]

Re: Harman/Kardon Onyx Bluetooth Speaker - No Power

So you think it's fine even though looks like there's a burn mark on top?