Harman/Kardon Onyx Bluetooth Speaker - No Power

[fzabkar]

Re: Harman/Kardon Onyx Bluetooth Speaker - No Power

A BAT54C (WW1) dual diode would fit the bill. That said, ISTM that your diode may be OK. AFAICT, D300 could be OR-ing the battery and regulator outputs to the Bluetooth module. This would allow the device to function in the absence of a battery. A voltage of 0.37V would then be a normal voltage drop (4.67 - 4.3 = 0.37V) for a Schottky rectifier at low currents.

      BAT54C

       3

 BAT+ o-->|---+---|<--o +4.67 from regulator
    1   |   2
       |
       V

     to Bluetooth
      module ???

[caphair]

Re: Harman/Kardon Onyx Bluetooth Speaker - No Power

Actually I got those pins wrong, according to this the w1 would have pin outs of the BAT54C

Maybe it's used as a reverse voltage protection diode for the charge chip

[caphair]

Re: Harman/Kardon Onyx Bluetooth Speaker - No Power

So I'm guessing it's a ww1 diode since the burn mark makes it hard to identify I found another similar one used in the over all circuit.

Found this https://cdn.badcaps-static.com/pdfs/...49ac0fb0cb.pdf

So going by that I measure
4.3v on tab 3 (cathode)
4.67v on tab 1 (anode)
.67v tab 2 (not connected)

So that's interesting. Not sure why it'd be blown, couldn't trace it to any circuit. Will try again later

[caphair]

Re: Harman/Kardon Onyx Bluetooth Speaker - No Power

Same output of charger ic .67v is measured on third pin of D300 while the other pins have 4.67v and 4.3v

[Agent24]

Re: Harman/Kardon Onyx Bluetooth Speaker - No Power

Also I was thinking, didn't the data sheet say to disable TS to connect a 10k resistor to the pin? Would that be an adequate test to try to bypass that section of the ic and see if it'll charge? Or just go ahead and try replacing?

AIUI charging is completely disabled if the TS pin is grounded. Therefore that won't help you to troubleshoot the circuit.

As for replacing the IC, I would wait for a second opinion.

The datasheet is confusing, but floating the TS pin should allow the charger to run by itself if everything is OK, if it doesn't, then something is probably wrong with it.

And 0v at battery terminals after testing unit with battery for a while, drained and never was able to charge back up

Sounds like it. Lithium batteries have inbuilt protection circuitry to disconnect them if they are over-discharged as this causes internal damage and using them afterwards is a fire risk.

The other thing I don't understand is how the battery came to be flat. I would have thought that the speaker would have shut down when the battery voltage dropped below 3V or so.

If the charger IC or some other part is bad, the battery could have just kept discharging through a shorted\leaky part, regardless if the speakers were turned off.

Just noticed this, does it look like a burnt mark to you on D300?

It does indeed.

If it was me, I'd remove the charge IC, check the resistors associated with it again and make sure they're OK, then assuming they are OK, install a new charger IC and new D300. Hopefully they are the only bad parts.
I guess you'll need a new battery too, of course.

Once you put them in, check the voltages again on first test, and run the battery through an ammeter so you see what happens with the charge\discharge currents and make sure they all make sense, hopefully replacing those two parts will fix it.

Are you able to determine what D300 actually connects to in the device?

[caphair]

Re: Harman/Kardon Onyx Bluetooth Speaker - No Power

Just noticed this, does it look like a burnt mark to you on D300?

[fzabkar]

Re: Harman/Kardon Onyx Bluetooth Speaker - No Power

AIUI charging is completely disabled if the TS pin is grounded. Therefore that won't help you to troubleshoot the circuit.

As for replacing the IC, I would wait for a second opinion.

The other thing I don't understand is how the battery came to be flat. I would have thought that the speaker would have shut down when the battery voltage dropped below 3V or so.

[caphair]

Re: Harman/Kardon Onyx Bluetooth Speaker - No Power

Thank you for that detailed explanation! Very much appreciated.

So should I try ordering a replacement chip?

Also I was thinking, didn't the data sheet say to disable TS to connect a 10k resistor to the pin? Would that be an adequate test to try to bypass that section of the ic and see if it'll charge? Or just go ahead and try replacing?

[fzabkar]

Re: Harman/Kardon Onyx Bluetooth Speaker - No Power

I could be wrong, but this is my understanding of how the charger works.

When the battery voltage is very low, the charger starts with a precharge current. This is set by the resistor on the PRE-TERM pin. In your case this current is 162mA.

When the voltage rises to a sufficient level, the charger then switches to fast-charge mode. The maximum current is then set by the resistor on the ISET pin. In your case this current is 812mA. During this time the charger monitors the temperature and may reduce the charging current in order to keep the temperature from rising above a predetermined maximum.

When the battery finally charges to a target voltage of 4.2V, the charger goes into constant voltage (float) mode. The current then gradually reduces as the battery's charge is topped up. When the current eventually falls to the pre-term setting, the charger switches off. In your case this current is 81mA.

The charger senses the temperature by injecting a 50uA bias current into the thermistor and then monitoring the voltage on the TS pin. The datasheet specifies a 10k NTC with ß = 3370 and it suggests the following thermistors:

(SEMITEC 103AT-2)
https://cdn.badcaps-static.com/pdfs/...bb9f97abfb.pdf (Mitsubishi TH05-3H103F)

The following table lists the TS voltages corresponding to various thermistor resistances and temperatures.

1.5V -> very cold, RT = 30K, T = -2 degC
1.0V -> cold, RT = 20K, T = 7 degC
0.5V -> normal, RT = 10K, T = 25 degC
0.2V -> hot, RT = 4K, T = 51 degC
0.1V -> very hot, RT = 2K, T = 74 degC

The IC will not charge if the temperature is too hot or too cold.

ISTM that the /CHG pin is indicating that the IC is charging.

The TS pin is reporting that the temperature is a little high. The TS voltage at 9830 ohms should have been around 0.5V but you measured only 0.2V. I think this section of the IC is damaged.

AIUI, the precharge current is 103mA when it should be 162mA. Therefore I think the corresponding section of the IC is also damaged.

The IC previously output 4.48V. AFAICS, this voltage should never exceed 4.20V, so I think there is damage in this section of the IC also.

[caphair]

Re: Harman/Kardon Onyx Bluetooth Speaker - No Power

Voltage on R709 is 0v both sides

I noticed the data sheet says that if TS is low to disable ic, I measure .29v on that thermal pin. Would that be considered low? If so does that mean the battery internal thermal circuit is bad?

[fzabkar]

Re: Harman/Kardon Onyx Bluetooth Speaker - No Power

The TS sensor bias current appears to be 20uA. The datasheet specifies 50uA. That seems like a problem to me.

(0.2 volts) / (9830 ohms) = 20.3 uA

The charging current appears to be 103mA.

Iout = V2 x 540 / (1.5 x R712) = 0.19 x 540 / (1.5 x 665) = 0.103 A = 103 mA

R710 (2K) appears to be the PRE-TERM resistor. AFAICT it programs the IC for 81mA termination current and 162mA precharge current.

R709 appears to be connected to the /CHG pin of the IC. A voltage of 0V indicates that the IC is charging while a high voltage indicates no charging or charge complete.

You should measure the voltage on R709 to determine what the IC is doing.

[caphair]

Re: Harman/Kardon Onyx Bluetooth Speaker - No Power

I had the battery connected for the voltage measurements, I'm guessing earlier when I had 4.48v was before the fault occurred, or when the battery was full.

On R712 I measure .19v

Thermistor terminal is .20v when being charged

Thermistor resistance at battery terminals with it disconnected is 9.83k ohms
Thermistor resistance at pin on circuit board with battery disconnected is 19.30k ohms

And 0v at battery terminals after testing unit with battery for a while, drained and never was able to charge back up

[fzabkar]

Re: Harman/Kardon Onyx Bluetooth Speaker - No Power

Earlier you stated that you measured 4.48V at the battery. ISTM that the battery should only ever see 4.20V from the IC, if I'm reading the datasheet correctly. I don't understand why you are measuring only 0.67V now, unless you have disconnected the battery for this measurement.

R712 (665 ohms) would suggest that Iout = 540 / R712 = 812 mA. That's the maximum charging current.

Can you measure the voltage on R712 when the battery is being charged? This will tell us the actual charging current.

Can you measure the voltage on the thermistor terminal when the battery is being charged? Can you also measure the resistance of the thermistor immediately afterwards, after disconnecting the battery?

I don't know what D300 does. It appears to be a diode, though.

[caphair]

Re: Harman/Kardon Onyx Bluetooth Speaker - No Power

Ok so on the in pin I have 4.68v and on the out there's only .67v

I thought maybe c706 might be pulling it down since it's connected to output pin, removed that and still .67v

Also that .67v goes to one end of D300 while the others have 4.67v and 4.3v. Is it a diode?

Is u701 bad? I don't measure a dead short from in to output pins

R712 has 80a marking which is 665 ohms and it measures 550 ohms
R710 - 30B - 2k ohms measures 631 ohms
R709 - no markings measures 0 ohms

[Agent24]

Re: Harman/Kardon Onyx Bluetooth Speaker - No Power

I think you need to verify the voltages etc on the charger IC pins.

Is it getting power in? Check Pin 1 for input voltage.
Check that the ISET resistor (R712) from Pin 2 to ground is OK.
Check the R710 on Pin 4 to ground is OK.
What do you get on Pin 8\R709?

[Agent24]

Re: Harman/Kardon Onyx Bluetooth Speaker - No Power

The TS pin (thermistor) is driven by an internal 50uA current source. Impressing an external supply voltage on this pin would have been a bad move.

I'm not so sure putting an external supply on Pin 9 would have been a problem. The datasheet says:

Temperature sense pin connected to bq24090/2/5 -10k at 25 ° C NTC thermistor & bq24091/3 -100k at 25 ° C NTC thermistor, in the battery pack. Floating TS Pin or pulling High puts part in TTDM “ Charger ” Mode and disable TS monitoring, Timers and Termination. Pulling pin Low disables the IC. If NTC sensing is not needed, connect this pin to VSS through an external 10 k Ω /100k Ω resistor. A 250k Ω from TS to ground will prevent IC entering TTDM mode when battery with thermistor is removed

And the TS pin, along with the rest of the inputs is spec'd at being able to handle from -0.3v to 7v.

I suppose it depends if those voltage limits were exceeded or not. Were they?

EDIT: Original statement "However, if he did pull the TS pin high, the charger may have tried to charge the output of the bench PSU. Perhaps this is where the damage occurred." seems incorrect. Re-reading post #96 it seems you had the battery connected normally but the bench PSU connected to the TS pin, so it should not have tried to charge the PSU if you enabled the charger by mistake.

[fzabkar]

Re: Harman/Kardon Onyx Bluetooth Speaker - No Power

Resistor R712 appears to be connected between pins 2 and 3 (Ground) of U701. If so, then this is the ISET resistor that determines the maximum charging current. Can you tell us the markings, or can you measure its resistance, with the battery disconnected?

Can you measure the voltage on R712 when the battery is being charged? This will tell us the actual charging current.

According to the datasheet ...

Voltage on pin 2 = Iout x (1.5 / 540) x R712

... so ...

Iout = V2 x 540 / (1.5 x R712)

[fzabkar]

Re: Harman/Kardon Onyx Bluetooth Speaker - No Power

You may be able to test the TS pin by measuring its voltage (Vt), then removing the battery and measuring the resistance of the thermistor (Rt).

This should enable us to work out the value of the current source.

Isource = Vt / Rt

AIUI, the datasheet specifies 50uA during charging, and 30uA when charging is disabled.

[fzabkar]

Re: Harman/Kardon Onyx Bluetooth Speaker - No Power

The output of the BQ24090 chip should be 4.20V when it has reached the final charging stage. That's the maximum voltage. If your chip is exceeding this spec, then I would say that it is faulty. In any case I would test for a short between out and input, with the battery removed.

The TS pin (thermistor) is driven by an internal 50uA current source. Impressing an external supply voltage on this pin would have been a bad move.

[caphair]

Re: Harman/Kardon Onyx Bluetooth Speaker - No Power

Possible. What exactly did you do when you were playing around with the battery and thermistor input?

I fed it an outside voltage of 4v from my adjustable power supply to rule out a defective battery.

Then I tapped into the thermistor pin on the circuit with my adjustable psu while the battery +/- were connected to the pins on the circuit board so I could adjust the thermistor voltage manually seeing if it would power on (obviously before we knew the issue was at the reset pin)

Also, with the removals of c306 and unit powering up was that enough to know the cap was the issue and not the transistor? (As further troubleshooting reference)

"So it all worked with your 2k resistor and C306 removed? With a new capacitor it measures 3.25v on the line?" it all worked with my 2k resistor and c306 removed and yes with new cap and original resistor I get 3.25v