Logitech Z506 power supply

[momaka]

Re: Logitech Z506 power supply

Ive got a dell 19v 3.4amp, will it do the job or is it overkill? i dont wanna go frying the thing.

A bit of a late response, but YES, this should work fine.

[DamiYa]

Re: Logitech Z506 power supply

Hey i used a 18.5v and 3.5A power brick. The speakers are working fine, but the volume controlling nob get heated a little bit. Why is that??

[ben7]

Re: Logitech Z506 power supply

Hey i used a 18.5v and 3.5A power brick. The speakers are working fine, but the volume controlling nob get heated a little bit. Why is that??

That is probably normal, it's heat from the components on the circuit board getting transferred to the volume control potentiometer, and to the plastic knob.

-Ben

[stromm]

Re: Logitech Z506 power supply

Hopefully it's OK to tag into this thread, I think my issue is related.

My z506 will present sounds for a few minutes at best. Then nothing. Power light is solid and stable. To get sound back, I must turn the volume dial to max. Oddly, with the volume at max, it never cuts out. However, there is quite a bit of background hum so if I turn down the input volume, that hum is too much.

I have tested different power sources, different audio sources (stereo and surround) and every case exhibits the same problem.

Does this sound like a power supply issue or something else?

Thank you for the help!

[Agent24]

Re: Logitech Z506 power supply

I had a very similar problem with a pair of cheap 'Milford Sound' speakers (TDA2282 based)

The problem was cracked solder joints on the headphone jack.

I'd suggest that to start with you inspect the PCB for bad solder joints and reflow any that look bad, also on anything that might take physical stress (like input\output jacks), volume control potentiometer itself, etc.

A more systematic approach would be to do signal tracing through the board, but it may not be necessary.

[stromm]

Re: Logitech Z506 power supply

Thanks for the info Agent24.

I have never used the headphone jack on the FR speaker. The wires don't get moved around either.

Do you mean the subwoofer unit PCB or the controlign speaker PCB?

[Agent24]

Re: Logitech Z506 power supply

Might be best to take a look at both. I say check anything that gets moved around first as it's more likely to fail. Try wiggling plugs etc and see if that also solves the problem. Then you might find out at least which board is the problem.

But bad solder joints can occur due to bad soldering from the factory, such as with mine - I never used the headphone jack either. So it's not always what you'd expect.

[stj]

Re: Logitech Z506 power supply

test with headfones, there is a pair of switch contacts in the jack that can tarnish.

[stromm]

Re: Logitech Z506 power supply

test with headfones, there is a pair of switch contacts in the jack that can tarnish.

No luck with headphones. The system presents sound till it seems like something warms up, then cuts out unless the volume is up all the way. Even with headphones connected.

Once it starts cutting out, if I remove power (cord) for five minutes or so, then plug it back in, I'll get sound as normal for a few minutes.

Does this seem like the power supply board?

[Agent24]

Re: Logitech Z506 power supply

No luck with headphones. The system presents sound till it seems like something warms up, then cuts out unless the volume is up all the way. Even with headphones connected.

Once it starts cutting out, if I remove power (cord) for five minutes or so, then plug it back in, I'll get sound as normal for a few minutes.

Does this seem like the power supply board?

I don't know. Others in this thread have certainly had problems with the power supply.
When you disconnect it from power for five minutes, do you disconnect the mains power from the wall or just the power supply from the amp?

If you have been disconnecting it from the mains, try just unplugging the power supply from the amplifier, and see if again it works after 5 minutes. You could also try measuring the power supply voltage and see if it changes between when the amplifier works OK and when the problem occurs.

It may also be something overheating or such in the amplifier itself. Can you post photos of the amplifier board so we can see?

If the amplifier section is bad, you might have to trace the audio signal through the amplifier and see where it goes wrong.

[stromm]

Re: Logitech Z506 power supply

Thanks Agent24 for some more direction.

Power is removed from mains. My life is fairly busy lately, so it'll be a couple days before i can take apart the main unit to get some pics and do the test you suggest.

Will post again when I do.

[stromm]

Re: Logitech Z506 power supply

I'm assuming these are not in good shape?

[Agent24]

Re: Logitech Z506 power supply

That black stuff is glue, and as long as it's only on the outside of the capacitor and not stuck to the leads, it's probably OK.

If it's on the leads of any components you should probably remove it, it can turn conductive over time and cause problems. Scrape it off with something, heating it with a hairdryer or similar (not too hot!) may help in removing it (can soften it a bit).

[stromm]

Re: Logitech Z506 power supply

Ah, good to know. Thank you for your patience. Even though I'm 45, I let my father (electrician by profession) fix all my electronics. Since he passed 4 years ago, I'm learning as I go now.

So I removed the power supply board and don't see any swollen caps, but I did find this brown stuff on these resistors. Is that more glue or should I remove and test them?

[Agent24]

Re: Logitech Z506 power supply

Yes that's more of the glue. As you can see, the yellow part is more the original colour and where it has come into contact with the warm components it's turned brown and started to corrode their leads.

Those resistors are probably still OK aside from the corrosion (though removing and checking them would not be a bad idea) but in any case, you should definitely remove the glue from them as it goes conductive and in a power supply this can lead to significant damage if the glue is somewhere in the primary side\high voltage section.

In lower voltage areas the glue does not usually cause catastrophic failure, but can upset circuit operation and cause a fault condition anyway.

[budm]

Re: Logitech Z506 power supply

That pix in post 74, that section looks like the RCD snubber circuit in the primary side so there will be high Voltage in that section.

[stromm]

Re: Logitech Z506 power supply

So if those are bad, would that cause audio to cut out after a few minutes?

Kinda wondering if I should just buy a new power supply board or if the issue is likely elsewhere...

[Agent24]

Re: Logitech Z506 power supply

So if those are bad, would that cause audio to cut out after a few minutes?

Probably not. If the snubber components failed, the power supply, or at least the switching transistor would usually blow up. Since this hasn't happened, it's probably not the case. But you should remove that glue to prevent it from happening in the future.

Kinda wondering if I should just buy a new power supply board or if the issue is likely elsewhere...

The problem likely lies in the amplifier itself, but of course it could still be a power supply fault. That is why I suggested you measure the power supply output voltage and see if it changes when the audio cuts out. You might also want to check that the output voltage in correct to start with - a voltage that is too high might make the amp work for a while, but then overheat and go into some protection shutdown state.

[Th3_uN1Qu3]

Re: Logitech Z506 power supply

It is recommended to scrape all the brown glue away. Also replace that little diode in the snubber circuit with a 3A 1000V fast or ultrafast recovery. That diode is the main point of failure in that power supply. A FR307 or HER307 will work, these can be scavenged from dead PC power supplies.

The diode is the black/grey component sandwiched between the two resistors and the green capacitor.

[Joun]

Re: Logitech Z506 power supply

Since a lot of people are having problems with those speakers, here's mine:
A friend brought it to me because they didn't work at all..aOf course power supply was bad.
I replace it with another 15V supply and it seemed to be OK..
That happened 3 monthes ago.Yesterday he told me that the sub wasn't working at all so he brings it back and sure enough he is right.
I search it a little and realise that the amplifier ic for the sub doesn't get any signal in its input pin.
I can search it any more without its schematics so does anyone have it?
Or any other solution from someone with the same kind of failure?

Thank you.

P.S Other speakers are working,only the sub section is defect.