Dead Play:5 need schematics or tips

I have two broken Play:5 units and when i check the “68b” resistor on them one reads 4.5 kOhm and the other one reads 12 kOhm, could the one that reads 12 kOhm create the problem you describe @timc995 ?

So we get a little further.. on the rectifier i have one ac leg at 240 and the other at 8. And dc output is 90v. So i measure back down the traces that u can see through the board and removed the mpx40 box cap. I get ol testing this. So it looks like when the reciifier blew it took this out and the fuse.i have some coming tomorrow hopefully. Ill report back once tested 

I think that one is more of a suppression capacitor connected between live and neutral.

Isn´t there a inrush current limiting varistor on the opposite side of the fuse at the input socket? Maybe it´s that one that is blown? 

Hi Dr_Phil.

Yes, if that resistor isn’t reading 4.5k, it will definitely affect the voltages.  I would say though, it is rare in my experience for a failure like that.  Resistors usually short out entirely, or blow open.  Landing somewhere in the middle (like 12k) is unusual.  It could be that the chip is actually ‘open’, but you are getting some other resistance measurement from the circuit itself.

I lost my info where I reverse engineered that part of the circuit, but the usual way that it works is that there is a reference voltage, and a feedback loop.  A simple voltage divider is made on the output voltages, and that voltage is compared to the reference voltage.  Often it is something like Vout=Vref*(1+V1/V2).  Vref would depend on a chosen reference voltage elsewhere on the board, and the circuit designer chooses V1 and V2 to get the desired output.  SO… If you are getting 12k instead of 4.5V, then your circuit is probably generating something like 5v/10v, instead of the required 12v/24v.

If you have a voltmeter, you can check what’s happening to the output voltages.  Also, you would ideally test that bad chip after removing it from the circuit, but these are so small that it may be impossible to remove it without damaging it.

I tested the resistors in front of the Q27621, they are all ok. But D27721 has 0.5 V in the forward direction, the value keeps increasing in the opposite direction.Think it's broken. Does anyone know what replacement parts I need?

For what it’s worth, my pin1/3 on secondary side are also shorted. So either we both have the same problem or it’s supposed to be that way!

Hi folks, the volume on my box is very low. I've already checked the resistors and changed the APM4307... but it's still very quiet.How do I recognize a defective transistor?And could someone tell me how big the capacitor C27861 is or which diode D27706 it is or how I can check,if the diode is defective?

Last resort is to add in a class D amp to it. Not ideal at all, but at least, sound is back.

 

How was the sound out of that class D Amp?

If decent, what brand model, and where did you connect? It looks like directly off of the wifi/controller board?

At low volume, I can hear the static noises. That will go away when I increase the volume. I got it from AliExpress.
Running at 12V and I may try to use 24V if that helps on the static. The connection is to the headphone out on the wifi board. Hope that helps.

ICE2QS02G  https://www.infineon.com/dgdl/Infineon-ICE2QS02G-DS-v02_00-en.pdf?fileId=db3a30431a5c32f2011abef4f7fd3bc8

I haven’t seen that before.  Check that the bridge rectifier isn’t broken.

After confirming that the bridge rectifier is working, try replacing the resistors and boot it up.  They could have died due to moisture or maybe some kind of transient making its way all the way into that part of the circuit.  There is protection against that, but anything’s possible.