Dead Play:5 need schematics or tips

I’ve just been repairing one of these, using many of the tips here.  Some observations for those following in the footsteps of many:

I had a blown fuse, then needed to track down what else was faulty.  Replaced fuse with same type. I thought the DC measurements were suggesting a problem with the MOSFET switch, so I changed that out with another N-Channel of similar value I had on hand.  The Dim Bulb Tester indicated there was still something wrong, but interestingly I was getting some useful DC voltages. My DC measurements of the bridge rectifier didn’t suggest it was faulty, so I pressed on. Decided to try plugging directly in to the mains. Big mistake. Loud explosion as the fuse self-destructed.
So stepping back I decided to use a process of elimination.  I removed both 100uF charge capacitors.  Replaced fuse, connected Dim Bulb Tester, still showed excess current.  I then removed the bride rectifier and replaced with another I had on hand.  Success: no more large current drain.
I intend changing out the 100UF caps with high quality brand, as well as the electro caps on the cold side.

But this failure of the bridge rectifier is a weird one.  I fix Switched Mode Power Supplies a fair bit.  Bridge rectifiers either go short or open circuit.  It’s as if this is failing under mains voltage?
Anyway, that bridge rectifier is a bugger to get out.  Removing the two 100uF caps gave better access to be able leverage it out whilst hitting it with the soldering iron (after having previously used a desoldering gun on those terminals).

Short circuit Player 5.

Dr Phil, your latest Post. Sorry I can’t find a “New Post” button on this page. Have to ride on yours.

Dead Player 5. Blown fuse. Installed larger fuse - tripped kitchen supply. Tested 8ohms across mains input. De-soldered/pulled one leg of the 2nd right-hand green filter coil (facing mains plug). Short cct now moved to bridge-rectifier. Meaning: replace the blown fuse but don’t waste time checking onward components to rectifier. It’s the 4-pin big black rectangular bastard behind the fat capacitor to the right.

Do not be dissuaded, have patients. Detach hot-glued components with drips of Isopropyl Alcohol bit by bit with screwdriver, easy-peasy. Firstly remove fat capacitor (notice white -ve polarity position). Second: the 4 rectifier legs. High class Sonos pcb (board) needs high temp narrow soldering iron bit. De-soldering braid and solder flux if you have it. Medium screwdriver leverage of component against board.

Yes, ESR tested both fat caps OK. Others too. Gonna replace bridge rectifier and fat caps. Awaiting delivery. And Comments / advice.

Short-circuit Player 5

Dead Player 5. Blown fuse. Installed larger fuse - tripped kitchen power supply. Tested 8ohms across mains input. De-soldered/pulled one leg of the 2nd right-hand green filter coil (facing mains plug). Short cct now moved to bridge-rectifier. Meaning: replace the blown fuse (small brown cylinder behind power input socket) but don’t waste time checking onward components to rectifier. It’s the 4-pin big black rectangular bastard behind first fat capacitor to the right of power input socket. 

Do not be dissuaded, have patients. Detach hot-glue from components with drips of Isopropyl Alcohol bit-by-bit with screwdriver, easy-peasy. Firstly remove fat capacitor (notice white -ve polarity position). Second: the 4 rectifier legs. High class Sonos pcb (board) needs high temp narrow soldering iron bit.

Use de-soldering braid and solder flux if you have it. Medium screwdriver leverage of component against board.

Yes, ESR tested both fat caps OK. Others too. Gonna replace bridge rectifier and fat caps. Awaiting delivery and, your Comments / advice.

Thanks Tim. You are truly helpful. Looking thru the datasheet, the Q27509/Q27503 on my board is indeed 34N B1, same marking placement as well. I am guessing those 2 blown would be the same.

Looking at my board again, only Q27515/Q27504 are labeled as DMB AN.

The rest like Q27203/Q27205/Q27303/Q27205 are all 34N B1

Fingers cross, thanks.

There are few examples in this thread about finding various broken components, where replacing/repairing them fix similar symptoms to what you have.  However, I have seen some bad Play:5 boards that I was never able to find the bad component and was unable to fix.

I’d recommend replacing the power supply.  It’s pretty cheap to install a 24v DC power supply (either external, or inside the case if you can get one to fit).  You would need a 24V->12V converter to provide the 12V supply too.  All of this is probably under $30.  This is described on this forum (I think in this thread but not certain).

Thanks Tim. I have not order the parts yet. 😀 will place an order for both 34N and DMB. Cheers!!

Hello, thanks for the picture.

I have-it fixed finally but I do not know the cause. Here it is in words and pictures:

First, small cap (C27854) is not charging from the AC side, those are probably discharge resistors to the remaining capacity in the filtering caps. It’s another mechanism I could not figure out. The C27854 is providing power to the ICE2QS02 driver chip. It goes thru all those small diodes and caps on the edge of the board. The normal behavior on the voltage for C27854 is that is charging up to around 20V slowly and then ( some of those diodes and transistors do that) turns on the power on the ICE2QS02. 

Once the chip is starting the voltage is self sustaining to around 13 V, I do not understand from where, maybe from the fly back transformer winding itself. 

So for me the challenge was to produce the charging of the C27854 up to 20 to start up the IC. I did this by putting 2 390Kohm from the + on the big caps. I monitor the voltage and it’s ramping up slow, like a second or two. After it reaches 20V the IC starts and it self sustain to 13V. It’s 3 days already and still works! meaning there is no other fail. There was no problem in the fuse or rectifier, nothing burned. As you can see the LED turns on with the 2 resistors soldered. This is the story of this fix.

 

I have no power on pin 7 on ICE2QS02 and when i measure on C27854 it goes from 9 to 18 VDC in a 2-3 second loop, is this the same behaviour as you had?

Thanks for the update!  That’s a great learning (at least to me) - what a pleasant surprise!

Thank you so much!!!

3 speakers are not working. sub and one middle are working.

i didn´t find these mosfets (in small quantities) in europe, so i´m gonna order at aliexpress. estimated delivery date end of may…

Mouser doesn’t have this in stock for me (in Canada) either, but they have this: https://www.mouser.ca/ProductDetail/Diodes-Incorporated/DMP3105LVT-7?qs=T%2FOtf55vL7eU%252Ba2ENkxGkA%3D%3D

Looks like it may be compatible.  It has some different specs, but it’s cheap enough that I’d be inclined to try it out rather than wait 2 months...

Hi all

I have been making some fault analysis at my own Play:5. Unfortunately the rectifier bridge and fuse is ok. The MOSFET driver at primary side is at least not shorted.

However the driver (FET, or BJT) at the secondary side is shorted between pin1 and pin3.

However I cannot figure out the tyoe, so it’s a little difficult. However a short circuit between legs is normally not something good ;-)

Or could I be tricked by the fact that the transformer might be connect to pin1 and pin3, so there is a DC short between pin1 and pin3 ?