Logitech Z906 5.1 Surround Sound

[m4a2t0t]

Having a issue with my speaker system. The control pod turns off and then back on after a few seconds to few minutes. If I push the power it turns back on and either stays on for a short time or turns back off. If I turn it off it will turn back on by itself after a few seconds to minutes.

Visually I only see one issue. On the bottom of the power board there are some transistors or VRs (2nd picture) and it looks like it's covered in super glue. I cleaned all of that crap off and resoldered both pins but no change.

I am testing with all cables disconnected except the AC power and the control pod. Also, sub disconnected from audio board. Control pod reset also performed. I've tried wiggling all the cables and tapping the control pod/sub but it doesn't cause it to immediately shut off or anything.

When the unit shuts off I still have 3.3V on the keep alive pin on the audio boards connector j17. There is also a constant faint tapping noise coming from the PSU when it turns off. The one thing I did notice, and maybe it was coincidence, if I short a pair of speakers cables the unit shuts off and turns back on after a few seconds.

Not sure where I should start looking. It could be one of the boards or even the control pod.

Thanks for any help.

[Moreno83]

Re: Logitech Z906 5.1 Surround Sound

The glue could be the issue but you need to resolder some of these parts........

It looks like bad connection on some of the solder pins.

[m4a2t0t]

Re: Logitech Z906 5.1 Surround Sound

What pins were you talking about that looked bad?

I cleaned up the soldering around those Vregs or whatever they are.

I noticed when I was taking the power supply out that the heatshrink was flaking off 2 resistors near the output connectors.

Can anyone tell the resistance values from the pics? They both measure around 6 ohms.

[R_J]

Re: Logitech Z906 5.1 Surround Sound

they likely run hot, thats normal, they could be 5.6 Ω, place your meter leads together to get your lead resistance and subtract that from what you measure the resistors value.
I would just put them back in. You could try replacing those 2 small caps beside them (C30 & ??) being close to the resistors the likely dried out.