Bose soundtouch 30 no power on

[crigab]

Hi guys, I have a Bose Soundtouch 30 to repair and I am stuck. I have 320V from the PSU to the mainboard, 24V on the amplifier, 5V and 3.2V, but pushing the power button, It is not powering on. I found a chip that it is heating when i plug the speaker in the outlet, but i can not find anything about the chip - C4E smd 8pin chip. It is anyone with some experience on this type of Bose to help me with some ways to find the problem? Thanks

[crigab]

Here is the sketch with the IC. Injecting 3.3V to 0V pins, i have 0.03A drawn from the power supply. for me is a litle high curent.
Also, injecting 5V to 7 and 8 pins, the IC is getting hot instantly. with a lower voltage the IC still get hot, but not so much
Any ideas? Thanks

[decoder77]

Hi,
TPS62067
https://de.aliexpress.com/item/1005007716413657.html

[dclass-pro]

Hi guys I'm checking an identical product but I can't find any test points anywhere to check and understand which board has problems.
Do you have any references to do some checks? the problem is that it doesn't turn on, but as soon as I insert the power supply I hear a low buzz from the switching circuit so I think it's active.
On the board with the lan port I have 310V in dc but on the 74HC02 integrated circuits between pins 7 and 14 I have 0V.
can you help me?

[Efbee]

Hi Guys. I am also trying to fix a Bose Sound Touch 30 with the same issue of it not powering on. In my case the fuse is blown, and my theory of what could have happened, is that a spike in the AC from the input caused the positive and negative lines of the two very thin rectified lines of 320VDC coming from the 2 varistors located over the two 450V caps and going through the J402 plug out to the Altair05T IC on the other board to short - there is a black short mark just right next to the J402 plug where the two lines comes closest. In the process the two SMA components, one each in series of the two 320VDC lines had blown. They are located just right next to the C404 X input line cap on the large component side of PSU board. Photo attached.

If you can indicate to me what those 2 components are (or what their board numbers are supposed to be), I will be so glad. I did obtain the service manual for Touch 30, but nowhere on the internet I could find a schematic to show the locations of the component items as listed in the manual - so I cannot pair them as only the largest items are marked on the board. I did find the service manual and very detailed schematic and explanation of how the system works for every section of the process of a Bose Sounddock 10 of which the PSU part is almost exactly the same as for this item - BUT this part of the circuit is handled totally different on the 2 systems. I can share if you want it.

I tested the boards with a 220VAC globe connected over the broken fuse and everything in terms of voltages on the PSU board is working fine with the correct voltages of 320VAC and 24VDC on the 3300uf large cap. Of course, the 2 exploded components were not able to pass the 320VDC to the other board to confirm that everything is working over there.

As a return favour for your help, I believe I would be able to give you feedback on your issue as soon as I replaced those 2 components and being able to test everything on the IO board.

[CapLeaker]

Efbee Probably nothing much and they can't be anything complicated, because something needs to be in series with each trace to complete the circuit and it is used to open up if a fault occurs.
They are either two zero ohm resistors, or inductors or fuses. There are 2 lines side by side. And the resistor should be inline on each trace. Whatever it is, it could be also bridged with a small wire strand. Upload the schematic using the attachment function and I'll have a look.

[Efbee]

Hi Capleaker, Thanks so much for replying. Unfortunately I do not have the schematic for the Sound Touch 30. I only have it for the Sound Dock 10 which is almost 100% the same PSU board except for this part that works totally different. In this case the positive and negative 320VDC lines run from the two triacs which are located over the 450v caps, then throughs these 2 components, then through a plug to the other board and there they each run through 510 Ohm resistors. The negative line then runs through a 22 Ohm resistor (R608 =3W), and then through a cap to ground as well as a 100k ohm resistor through a diode's cathode side to pins 13 to 16 of an IC (Altair05T) which drives a small transformer that provides the power for the bass speaker (i think). The positive goes to a cap and also to two 1.5 ohm resistors in parallel connected to both pin 1 and 2 of the same IC. I believe your idea is correct, but I am a little skittish of just putting in a bridge on a 320VDC line (for the sake of the board). I am thinking maybe something like a 10 Ohm resistor each as both lines runs through a 510 Ohm resistor in any case?

[CapLeaker]

It's DC, so wouldn't make much sense to have a diode in there. What ever it was, it is in series, so it has to pass power. The only two things that make sense is either a jumper (0 Ohm resistor) or there was a small inductor there. I also think the next task of this device was to protect, basically act as a fuse. Makes me even more go with this jumper or 0 Ohm resistor idea. Series resistors is like all resistance in that line counted together. I don't think that it cares if you have a total of 510 or 520 Ohm resistance. That's within 5% tolerance of the 510 ohm resistor alone. Can you draw a little schematic up and upload it here using the attachment function?

[Efbee]

Hi, I tried my best to reflect the content of my previous post into a schematic of the immediate area of my issue. I made a few mistakes in my original explanation, but at least I think they are now more correct on the schematic. Capleaker, I think you are 100% correct in that those 2 components are there as fail items to prevent a catastrophic explosion of the tracks when a short happens alongside that 320vdc line - the slow burn fuse is just too slow to prevent that, although it did fail in any case. Apart from the fuse, one of the tracks on the negative line, inside the layers of the board also did fail. I can see the black part and a blister in the board where it happened by shining a sharp light from behind, but that I can easily fix with a wire and luckily there are no other components around there. Everything else around tests good and I do get the stable 24v over the 3300uf cap, so now I'm just going to fix that track, bridge the 2 components with a strand of wire each and test it with a 220v globe over the fuse. Whish me luck, I will report back on either my success or failure. PS. the 16pin IC is the Altair05C.

Is there anyone out there that might be able to help me to find test points for other voltages if this fails.

[CapLeaker]

That’s what I thought the circuit looks like. Fix that track, install small jumpers, measure with your DMM across the HV DC lines in diode mode. If no short, give it the berries and it should hopefully turn on.

[Efbee]

Success!! Wow, was I glad when starting it with the 220VAC globe in place and it giving just that one blink. No explosions happened and the next moment the download bar started building in the display. So yes, thanks a lot CapLeaker, your suggestions worked, and I was able to run some music through the AUX with no interference. I must say, I did test most of any surrounding components, and I could not find a single anomaly.

I decided my next best step is trying to get it back to as close as I can to the original state, especially due to the system being able to protect itself during that original explosion on the 320VDC line. I have to order the correct slow blow fuse online in any case, so I decided to order some SMD ceramic inductors as well, as I agree that is what I think the original ones were. I just first want to measure the DC amps running through each line when playing music at top volume. If I pick inductors with an Amp ratings slightly higher than measured, I feel it may give the same level of protection as original. Taking the schematic in consideration, do you agree that inductance in the nH range should not be an issue in this situation?

So, my wife asked what caused the original explosion of those 2 components in the first place. My latest theory is that it was a bug. Meaning a real physical bug! I found the remains of a small bug about 2cm from where I found that black spot between the incoming 220VAC incoming plug and the outgoing 320VDC plug where the two lines comes closest together (about 2 mm) and where there is an open vias cylinder hole in each line. I think the bug actually walked over that death trap and got violently electrocuted by the 320VDC! RIP bug! Photo attached of the bug remains and the exploded items after cleaning.

[CapLeaker]

Wouldn't be the first time that a bug(s) causing carnage like that. Glad to hear you got this thing going. From what I see on your close up carnage pics, the 2 whatever SMD pieces are 0 ohm resistors. No more no less.

[Efbee]

Thanks again. I will look for some SMD zero-ohm resistors of similar size, so that the wattage/point of failure stays similar to what it was before. With my strands now over the contact points, I am not at all sure what amps it will handle as either too much or too little might cause a problem. Which brings me to something I still want to do - I want to test the amps there when music volume is at its highest.

[CapLeaker]

With SMD the wattage and voltage depends on size. You can put in this circuit a fast blow fuse, an inductor or a jumper of some sort. The worst that can happen is blowing out a trace and it did that already kind of anyway. Of the pictures I can't tell what size they are. You know the circuit, you know the voltage, and you know the size of the SMD device. This all aides you to determent the correct solution.
Physically it doesn't matter much on what that original device was as long as lets power through it. You know the device was black and the size and the voltage / wattage it needs to handle.

[CapLeaker]

I found this service manual for a Soundtouch 30. While it does not contain a schematic diagram, I’d did contain a full parts list.
So I went through it to see what they could have used. And found out they didn’t use any 0 ohm (jumper) resistor. They either used an inductor or a ferrite beed. And I think it is the ferrite beed with the warning triangle on it. L401 and L402 or FB401 and FB402.

[CapLeaker]

Made a few pics