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  1. #21
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    Re: Problem with Logitech Audio PCB (No Sound Output)

    The datasheet for the CD6282CS says its absolute maximum allowed power supply voltage is 15V or 16V so your 18V might blow them up.
    I did not see your photos because Imgur is still asleep.
    Why are you trying to fix the very cheap Logitech sound system anyway? The electronics recycling depot at the garbage dump is full of defective ones.



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    Re: Problem with Logitech Audio PCB (No Sound Output)

    The top picture looks correct to me, assuming the number refer to the actual pin numbers on the IC.
    Be aware that reversing the IC will probably kill it, even if it doesn't get hot.

    However, just replacing parts randomly is not a good strategy to fix it. Put everything back as it was and compare the two amplifier voltages. The left and right channels should have near identical voltages on them so place your negative meter probe on the negative side of the big capacitor in the PSU then move the positive meter probe to compare pin 1 on each amplifier, then pin 2 and so on. Write the voltages down on each IC and tell us what you found.

    Brian.
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  3. #23
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    Re: Problem with Logitech Audio PCB (No Sound Output)

    Just a quick question:

    If I change the 3300uf 25v capacitor (current PSU capacitor) with a 2200uf 16v capacitor, will it work?

    Also, I just found a somewhat specific CHMC production D6282 IC description with pinout. It is the same as IC CD6282CS. You can see here says, the same volt max output 6 - 15v.

    https://imgur.com/Bfp2Aq9


    Hope I can get some results with the IC replacements again.
    Last edited by Blackdragonier; 16th August 2019 at 09:19. Reason: Adding more information



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    Re: Problem with Logitech Audio PCB (No Sound Output)

    If I change the 3300uf 25v capacitor (current PSU capacitor) with a 2200uf 16v capacitor, will it work?
    It might but it won't work as well and you risk it being damaged or even exploding. You can generally increase the value and working voltages but you should never reduce them.
    If that part was faulty all you would get is a loud buzzing noise from both speakers. It has nothing to do with your present problem.
    Please follow the advice I gave in post #22 and tell us the readings.

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    Re: Problem with Logitech Audio PCB (No Sound Output)

    Your 18.22V power supply voltage is too high for those ICs.



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    Re: Problem with Logitech Audio PCB (No Sound Output)

    Update:

    Things I have done so far:

    1) Replaced IC#1 CD6282CS with new IC CD6282CS.

    2) Put back IC#2 with old IC CHMC S2702 D6282. Because I ran out of new ICs'.

    3) Still no sound output. No heat on any IC.

    4) Here is the chart for output measured volt on each of the pins of each of the ICs'. As instructed, I put the black probe of the multimeter to the negative side of the PSU capacitor and used the red probe on each of the IC pin's voltage to be measured.

    https://imgur.com/q3ZZ2mv

    If the image doesn't load let me know. I will try describe it here.

    Hoping to get some help soon.

    Regards
    Dragon
    Last edited by Blackdragonier; 22nd August 2019 at 08:13. Reason: Grammar mistake



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    Re: Problem with Logitech Audio PCB (No Sound Output)

    The slight differences are nothing to worry about.
    If one channel works and the other doesn't but the voltages are almost the same, it suggests the fault is not in the amplifier at all. As an experiment, can you cross over the loudspeaker connections, (left speaker to right) and see if the fault moves to the other side. If it does, the loudspeaker unit itself is faulty.

    Brian.
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  8. #28
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    Re: Problem with Logitech Audio PCB (No Sound Output)

    Hello and thank you Mr. Brian.

    I also forgot to mention that the PSU capacitor is showing 16-17v reading.

    About changing the sides, how am I supposed to do that? Could you please elaborate on that part?

    Also, should I change the mini capacitors and resistors (if some of them have lower values)?

    Is there anything I should focus on?

    Waiting for your reply.
    Thanks.



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    Re: Problem with Logitech Audio PCB (No Sound Output)

    I'm looking at the 0V readings at pins 5 through 10, on IC#2. That can't be normal.

    IC#1 gives 0V only at pin 9 which is labelled ground.



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    Re: Problem with Logitech Audio PCB (No Sound Output)

    I agree the voltages look slightly out on IC#2 but they are at least all shifted by the same amount. The photographs clearly show the grounds are actually all linked and if a ground break had occurred the pin voltages would be much higher.

    I'm aware that the first 'gut reaction' of the inexperienced is to change the IC's then the capacitors then everything else instead of isolating the real fault and fixing it. Rather like one headlight on the car not working so you change the engine, then the battery then the windscreen and the blown bulb is still there and not working.

    By checking the speaker wires I mean that both amplifiers are on the same PCB but presumably the loudspeakers are in different boxes. Where your photographs are marked "Output", I presume there are wires that somehow end up at the loudspeakers. Can you find the connection to the right speaker and swap it temporarily with the one to the left speaker. The idea is to keep the electronics as it is but see if the fault transfers to the other speaker when the wires are crossed. If it does, the amplifier is probably not the problem but something in the wiring or the loudspeaker itself is causing the fault instead.

    Brian.
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    Re: Problem with Logitech Audio PCB (No Sound Output)

    Hello to all.

    Mr. Brian I understood the the swapping issue you explained to me. Thank you very much for that. But if you look the picture I shared at the starting of this topic, both of my left and right loud speakers are attached to a single 3.5mm jack. And it should be attached to a single output female jack on the PCB. So, there is no way that I can actually swap the left and right side of the speakers.

    https://imgur.com/gH1ao8G



    https://imgur.com/tpinTv2




    Speaking of the swapping, I strictly mentioned with my updates that there are no sound at all now. Even after replacing with good ICs', there is not even a single buzz sound. So, it is also hard for me to say whether right or left side has a sound issue., as they both seem dead to me now.

    I am hoping to get some help about the audio output system.

    Thanks in advanced.
    Dragon



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    Re: Problem with Logitech Audio PCB (No Sound Output)

    Can you plug the loudspeaker jack into something else to try them? I'm trying to confirm the fault is electronic and not just a faulty loudspeaker, the symptoms can be the same but the repair is completely different.

    I am busy over the next few days working at my town annual carnival "DyfiFest" so I may not be able to reply straight away.

    Brian.
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  13. #33
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    Re: Problem with Logitech Audio PCB (No Sound Output)

    yes off course you can u can use audio jack on the place of mic https://envirementalb.com/lm386-audi...ifier-circuit/



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    Re: Problem with Logitech Audio PCB (No Sound Output)

    It is possible that damage to the circuit caused by the screwdriver buzzer and installing one or two ICs backwards caused the full DC supply voltage to be applied to the loudspeakers, destroying them.
    So it is important to hear if the loudspeakers work or not.
    EDIT: The first post says that the speakers work fine when plugged into other sound source products. But maybe the speakers do not work NOW.

    - - - Updated - - -

    Look at the photo of the replaced ICs that are backwards and have poor soldering:
    Last edited by Audioguru; 23rd August 2019 at 21:21.



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    Re: Problem with Logitech Audio PCB (No Sound Output)

    Hello everyone.

    Thank you all for your suggestions.

    The loud speakers work just fine with my android cellphone (as headphone plugin for 3.5mm jack) and also with my laptop.

    I am still waiting on the output side problem.

    Regards
    Dragon



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