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Subwoofer on Sony HT-CT290 sound bar not working

The subwoofer on my Sony HT-CT290 has suddenly stopped working.

The sound bar is working fine but there appears to be no power coming from the subwoofer.

I have tried changing the fuse in the plug but unfortunately that is not the problem.

It is 15months old and I have spoken to Sony but it was only covered by a 12 month warranty typically.

Update (02/05/2020)

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@tiffanylaw "The sound bar is working fine but there appears to be no power coming from the subwoofer" how and what did you already check? What works and what does not?

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The sound bar powers up fine and works as usual but there appears to be no power to the separate subwoofer, there used to be a green light that appeared when the unit was on I believe and this is located on the front below the top speaker but this is not illuminated now.

I have tried plugging it into multi sockets and I have changed the fuse in the plug.

Any other ideas I could try would be greatly appreciated.

The only control on this unit is a power on button and a link button. Kind regards Tiffany.@oldturkey03

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Hi @tiffanylaw ,

Since the warranty is no longer a consideration, you will have to open the sub woofer up (with the power totally disconnected) and check if there is anything amiss on the control board or power board (there may only be one board) such as burnt out or ruptured components.

Post some close up images of the board(s) back here so that others may be able to help you further.

Here's how to do this

Adding images to an existing question

If you have a DMM (digital multimeter) and know how to use it, it may be a help in finding out what's wrong if nothing is obvious.

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Ok thank you very much I will do this and post pics ASAP.

My son has a multimeter so he may be able to assist with showing me how to use it.

Thank you for your help. @jayeff

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I have removed the back and this is what is inside.

I will have to wait for my son to get home for him to show me how to use the multimeter.

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Hi @tiffanylaw ,

There is nothing obvious showing in the pictures so it will come down to doing some tests, initially static testing (without the power connected) but after that it will need to be with the power connected.

If neither you or your son has any experience testing when exposed lethal voltages are present then don’t do it. It is not worth it

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(click on image to enlarge for better viewing).

I’ve highlighted some points of interest in the image above where you may wish to check first.

With the power disconnected (green arrows) use an Ohmmeter:

check that the fuse on the ‘power’ board is OK i.e. short circuit measurement shown on Ohmmeter

can’t see it to well but if the regulator shown on the ‘amp’ board is a TPS54334 then these are prone to failure over time.

Not quite sure what you would measure when testing the regulator with an Ohmmeter in this particular circuit but you shouldn’t see a short circuit or an open circuit when testing across the pins. There are actually two regulators in the same package

If it is faulty and you cannot find a direct replacement a MP2307 is an equivalent component.

You will need smd (surface mounted device) soldering tools and skills to remove / replace the component

If it is determined from the static tests that the two check points suggested are both OK (green arrows) then you will have to connect the power and perform “live” testing. See note above re testing live circuits.

Again can’t see it too well and I haven’t got a schematic to work from but the red arrow points to what I think is the STBY (standby) power lead going from the power board to the amp board. This should be a DC voltage, its’ value is unknown to me, but given the regulator operates at anywhere between 4.75V DC to 28V DC you shouldn’t see any DC voltage higher than the 28V DC

Check if there is a DC voltage on the lead.

If there isn’t then there is a problem in the power board.

If there is then there is a problem on the amp board as the STBY power is to let the amp board “know” that power is available and it switches on the power light.

Be aware that there is exposed lethal voltages on the power board when you’re doing this.

Hopefully this is a start

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Thank you so very much for taking the time to reply in such detail.

When my son comes home I will see if this is something he is competent to do and we will go from there.

If not I may look at finding someone in our area that may be able to take a look for me.

I don’t suppose anyone knows of a business or person in the Swindon area that is knowledgeable in this field?

Thank you again @jayeff

Tiffany

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hi @tiffanylaw ,

Hopefully there may be an electronics repair service in your area that may be able to deal with it.

If there is, to save time (therefore labour costs) mention that you have been informed about a possibly faulty regulator as being the problem.

Alternatively if you are willing to take a gamble and purchase the regulator (search for it online by searching for the component number above) and your son (or you) is willing to try and replace it then it may also work out.

Good luck ;-)

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Thank you so much @jayeff you have been fantastic. It is very much appreciated.

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Hi, unfortunately i have the same problem.

The answer is replace the regulator?

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@gz.c

If you're asking whether to replace the regulator, then have you tested it at all to see if it is short circuit or open circuit?

Here's the product link that shows the circuit of the IC.

They are not that expensive so you can always try replacing it and check what happens. This is assuming that the Standby voltage from the power board is OK

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As mentioned by @jayeff, the TPS54334 regulator was the problem, however I don’t have the equipment to resolder since it turns out this chip also has a soldered thermal pad under the chip. I did happen to have an LM2596 DC-DC buck module (about $1.50 from amazon). I connected it to the 18v supply (soldered to pins 2 & 3 of CN8102 connector) and ground (thermal pads that were under the chip) and set the regulator output to 3.3v. Then I connected the output to the two large tabs (assuming test points) just above the chip (make sure to get polarity correct). No SMD soldering required. I used some heat glue to stabilize the board since there will be a lot of vibration from the woofer. Here is picture of the results - notice the blue module with LED where the chip used to be:

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Hi Matt. Im just about to embark on repairing a friends unit . Question before installing the LM2596 did you completely remove the OEM IC ? In your picture its clear to see the red + IN but what about the -IN ?

Cheers

Phil

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I did completely remove the chip first. In fact it was a bit difficult since the thermal pad underneath was also soldered so it took some persuasion to remove the chip after I removed all the solder from the accessible pins.

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Just cut it out with some cutters... I used these Flush Cutter C.H.P. CHP-170

Cleaned up the joints after removal and soldered the buck to the places mentioned on the board. IT POWERS UP NOW!!!!

Thanks!

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Hi everyone!

I have HT CT 290 sound bar. Which was burnt due to voltage fluctuations. Now I have to get the board replaced because I have got it checked from the repair guy. But I am unable to find this exact board. Can someone help. The board is exactly the same that is shown in above picture.

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Same problem. Did the LM2596 DC-DC buck module Solve ir. Thanks

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Hi @steve_t

OK some info.

Here's a supplier for the 3.3V standby voltage regulator

Here’s a link for the 5V regulator EUP3482ADIR1. I don’t know where they are located, but they quote in GBP

Here’s the service manual for the sub woofer . Sorry about the link to the main unit service manual in my comment above.

This link is harder because you have to view it online and go from page to page by typing the page number in the box below the document page and then click go. To download it you need to sign up with the website.

The regulators are shown on p.15. It seems as though the 18V output from the power board supplies power to the regulator to produce STB_ 5V and presumably when the unit is turned on it becomes SYS_5V and the STB_5V also feeds to the regulator for the STB 3.3V

Check the outputs of the two regulators. The circuit shows the pins. Apologies if you know this etc

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Thank you Jayeff for your replies, this is a great help. I will do some further testing. Thanks also for the links to the parts. I appreciate your time!

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just replaced the regulator TPS54334  and it worked, many many thanks Steve T

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@jayeff thank you. very talented.

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How did you change the regulator , seems to be very complicated with a lot of pins !!

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Hi @ emmanuel.barbeau

If you are referring to the TPS54334 IC then it is only an 8 pin chip

Search on YouTube for how to solder 8 pin smd chips to get an idea of what to do.

As answered above by @matt10, the difficulty with this chip is that it seems to have a thermal pad underneath it which also has to be soldered.

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Hi @M Kuzma

Here’s the service manual

Haven’t had time to review it but but has the schematics so you should be able to work out how the power gets to the regulators on the mainboard to provide the different voltages and also what type of regulators they are. Once you know the regulator model number, search online for replacements using the model number of the component. Search on places such as mouser.com, digikey.com

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Maybe you have gmail or messenger. I want sent to you some foto whith voltages,

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@jjanishas

You are placing your comments all over the place in different answer, which makes it difficult to know what device you have as there are answers on this page to different models e.g. Sony HT CT-290, HT CT-180, & HT CT-260h.

I don't have any further information on the HT-CT290 as I said in the Chosen Solution I couldn't find the schematics so all I could do was look at the image supplied in the original question at the top and I noticed the regulator was one that I had problems with before on another device.

For me without a schematic I wouldn't know what to expect as to what the voltage should be because I cannot work it out without one.

Finding faults at board level without a schematic is very difficult if you are unfamiliar with the circuit which in this case I am. With a circuit it may be easier.

I don't think that I can help further

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Thanks i have sa wct 290.

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@jjanishas

You may have been using the wrong information from this page

You have a different model than what the models on this page are all about. A Sony SA WCT-290 is different to a Sony HT CT-290

Here's a link to the service manual for your model.

Follow the appropriate flowcharts on p.11 or p.12 to see where that leads you.

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Thanks, i trie to find problem.

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Tiffany Law will be eternally grateful.
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