BOSE Solo 10 Help - No Power Up - Pics + PCB Part List

[Jordan3Dtek]

Hello,

This is my first question and post to this forum, so please do bear with me

I have a Bose Solo 10 sound unit that will not turn on, it's a friends who said it was working fine before than after about an hour or two the system would shutdown. Now I can't seem to get it to power on at all.

The owner said it was working fine until a power outage, which very well could of blown something.

Attached are some high quality photo's of the front and back of the main board. I don't see any noticeable issues, and it doesn't appear to have any blown caps or burnt components. I am thinking that rather large 450V Capcitor [Labeled: C1215] (100UF, EL, 105C, 20%, 450V) could be the issue, but just wanna make sure there is no other glaring items I should check first.

Unfortunately I don't have a Capacitance Meter, looking to get one asap. Willing to take out components and test them if anyone can provide a little assistance. Thanks for your time.

HQ IMAGES AVAILABLE HERE: https://drive.google.com/open?id=1aKhPPMrxDxip2glDUwqHI34cfxHqj8-8
-also uploaded here-

The dis-colorization of the board was cleaned up, which to be thought heat buildup but possibly water damage, can't tell exactly but the board still doesn't work after cleaning up and brushing off any corrosion on any contacts particularly the cage contacts.



(A Cage screws over and under the Power Supply Components)
**Also I have the Service Manual for the unit in PDF, it lists every PCB component which is great to have, check it out(Attached) if you want references to the components I am talking about**

 

[dave9]

If this has water damage it could be a real PITA to troubleshoot. That could short out *anything*.

Why do you suspect the 450V capacitor? In the pic it does not look vented to me, or do you see crusty dried electrolyte leaking out the bottom? I mean crusty like salt, not just some cement holding it down securely on the PCB.

You could check to see if there's voltage coming out of that D1301 schottky rectifier just to the right of the transformer, but I would sooner suspect a power surge during the power outage event has blown either the bridge rectifier BR1201, or the PSU switching transistor(s), 4 in a square between the 450V cap and the transformer.

It's great that you have a parts list in the Service Manual, but it is a bit lacking in not having a schematic. That would greatly simplify determining where [and when] to take voltage measurements. Without that, remotely describing how to trace along the circuit paths is going to be difficult if reasonable at all in a forum topic, besides what I've mentioned already about D1301, to see if the PSU circuit is putting out (a value that seems like the right range of) voltage.

 

[Jordan3Dtek]

Thanks for the input, I will check it out. No doubt a schematic would be great but really unlikely to find from bose. I just have repaired Caps before that have blown in similar circumstances but I will take your advice and check those other components out. Will update when I got something more, thanks!

 

[dave9]

...I would sooner suspect a power surge during the power outage event has blown either the bridge rectifier BR1201, or the PSU switching transistor(s), 4 in a square between the 450V cap and the transformer.

Looking at it again, I don't see 4 in a square, just two... apparently my monitor is adjusted to low brightness, combined with your low brightness pic, made me guess that the two shadows I saw were two more transistors.

 

[Jordan3Dtek]

The Bridge Rectifier checks out and is providing ~156V DC which is correct for a 1.4 power factor (Original Input is 113V at the moment). I am going to remove the Schottky transistor that you have suggested to inspect further. If it checks out than on to the those two small ones. I was not getting normal readings from that D1301 schottky transistor while in circuit. Same with the two before that, but I think testing out of circuit is the next bet. Let me know if anything I am doing doesn't make sense. Is there a proper way to test voltage coming out of the transistors, just wanna make sure I don't short nothing that shouldn't be. Thanks for your time.

I got the main D1301 out of circuit and will test it, I don't think my voltage meter supplies enough voltage in diode mode (<1.5V DC says manual) to properly test it, will keep researching!

 

[dave9]

No need to remove the schottky, I mean first you would measure whether AC voltage is getting to it. If there is, and no DC after it, it's bad. If there isn't, there is something upstream of it that's at fault.

Similar is true of the transistors. I don't recall, is there a fuse and if so I presume you checked and it wasn't shorted? Transistors that fail closed circuit would tend to fry (visual sign most often) and/or blow a fuse, whichever happens first. Open, you wouldn't get voltage out of them. Proper way is multimeter, it's now DC since it has passed through the BR1201.

However now that you got D1301 out of circuit, your meter should supply enough voltage to check that . It's just two schottky diodes, bound to be under 1.5V at the very low test current.

 

[Pingo]

Hello Dave,

I have the same problem with my Bose Solo, he does not turn on. At D1301 I measure around 24 volts, so it seems that the powersupply is working. Maybe you have an idea where I could look? I also tried a reset, and get no lights or sounds.

Greeting,

Gordon

 

[Jordan3Dtek]

Ya, exactly the same with mine. I am gonna be replacing a few parts, just to see if they cure the problem. The bridge rectifier did, before I removed some components for bench testing, have an AC Voltage past the rectifier. I am not sure if that should be the case in a normal working rectifier. I am replacing some components when my order comes in (Hopefully this week) and will post my results. Unfortunately I am going at it a bit inefficiently, but for $20 in parts its worth the experience and practice soldering. Do me a favor and check and see if you are getting AC volts on the DC side of the circuit. (Full disclosure I'm not an electrical engineer, just a enthusiast who likes to tinker, and solder)

 

[Pingo]

Hi Jordan,

Nice that you react, at the moment I have some parts on the test bench, so no measurements can be done.
I am not an electrician like you, but I like soldering. I also ordered a number of parts on the bet. If I have become a little wiser, I will post it here!

greeting,

Gordon

 

[Jordan3Dtek]

Yes that is the same as me right now, cant test til I got it wired up again.

I have found this video that actually just got uploaded 1 week ago on youtube.
It is the Bose Solo unit being diagnosed by a youtuber with similar issues. He explains it in more detail, and I understand more about the board now.

Thought it might be of assistance:

Fortunately I have ordered one of the components that he changes out, but might require the other 2 (Smaller Chip he replaces, and the transistor(the one missing in his video)). Will update when I got new components in, and some sort of test results! Parts will be here tomorrow hopefully.

 

[Pingo]

Hi Jordan,

Thanks for uploading the video! I have searched everything on the net, but it is new indeed! I also ordered this FAN chip on the backside of the Pcb, but the secret one i dit not order jet. My transistor seems to be still good. we keep each other informed!

Greeting,

Gordon

 

[Pingo]

Hi Jordan,

Thanks for uploading the video! I have searched everywhere on the net, but it one is new I also ordered this FAN chip on the backside of the Pcb, but the secret one i didn’t order jet, because I don’t know which one I must have. My transistor seems to be still good. we keep each other informed!

Greeting,

Gordon

 

[Jordan3Dtek]

Same aswell, I did not receive my order today, and the way Canada Post has been striking I might not for a couple weeks.

While trying to find that as the youtuber states "Magic Chip" I couldnt find that model number:
337R
21-1

After analyzing what he put back in:
74AX (his oddly looks like 7A4X to me? but the below part number checks out as a suitable chip)
21-2

I was able to find the part number:
74AXP2T3407DCH

I have an odd feeling that chip on the original bose board was made by some off manufacturer with maybe "intentional" failure in mind? Hmm who knows til we crack this BOSE code. Will update when I got the rest of the components in, and if all else fails THIS CHIP. *The true tell tale sign will be if we BOTH replace the exact same part and they both come alive* In that case I will SO make a bose roast youtube video. =) Cheers.

 

[Pingo]

Hello Jordan,

it's me again, We are talked about that “74axp2t3407dch” chip, I have doubts whether that's the right one! I have figured out a bit and added some pictures.
what do you think? The orginal chip on the board is 3mm x 3mm. In the picture the size is smaller. Also it has 2 x ground, the original one has only 1 x ground, I measured that today.
Maybe I am wrong..

cheers

 

[Jordan3Dtek]

Well thanks for that information! I haven't had a chance to really test that. Your info is most valuable. Well now to tracking down that chip... Any leads on what chip it is? The youtube video I showed you; I had commented and he replied about it being the FAN chip or that one. Gotta find that "Secret Bose Chip"! Will keep looking, we seem to be getting closer, I'm hopeful.

 

[Jordan3Dtek]

This is gonna be a tough one, there are many chips that could fit that spec (MSOP-8)
Canidates so far given the possibility of what it does:
http://www.ti.com/lit/ds/symlink/tps7a4001-ep.pdf or maybe http://www.ti.com/lit/ug/slvu448/slvu448.pdf

First thing would to find would be the required rated voltage of this thing, than current, or what type of chip it is would vastly narrow down the results. Maybe someone from the heavens will comment on this thread with more wisdom =).

In the mean time I have been searching the parts list for anything that could be it, so far nothing shouted out at me. Will be alot better if I can cancel out this chip once I get my chip order in.

 

[Pingo]

I do not think that chip is on the list. but I have just searched, it could be this one below in terms of numbers ..

 

[Jordan3Dtek]

That sounds very much like it. Did you find that Image in the video or have you find that else where?

Just wanna update my actual chip is labeled as: 32DJ 21-1. I think the 21-1 or 21-2 is what matters, if that is indeed the correct chip than I think you could use a 21-2 (Like youtube video) or a 21-1 but in that spec sheet it states "The LM5021-1 has a maximum duty cycle of 80% while the LM5021-2 has a maximum duty cycle of 50%" so that can affect something possibly but wouldn't think it would enough to notice or damage anything(Could be very wrong tho, no garantees) I think I will attempt to order a LM5021-1 just gonna double check the ground pin location to see if it matches up.

 

[Pingo]

Hi,
I found this chip somewhere else, I find it by searching at (21-1) not in the video. I've added the pinout. I also think that 21-1 is important information and that the top numbers and letters always change. I added a picture of my chip on the board.

 

[Jordan3Dtek]

I am fairly confident that's it, I will be standing by until I get my first batch of parts [Still waiting ] than after I test it I will see if one last order can solve this. Will update when I have some answers. Thanks for the assistance!