Saturday, September 5, 2009

Samsung Home Theater HT-X40 - Shut Down on Protection Problem

A couple of days ago my Samsung home theater HT-X40 started periodically shutting down with "Protection" message. Resetting by the "Stop" button pressed for 5 seconds made it forget all settings but did not fix the shut down problem. From the cool start it took about 20 minutes until it switched off for the first time and 2...3 minutes after re-powering while it was still warm. That behavior clearly indicated a problem depended on heating.Disclaimer: Repairing electrical and electronic devices requires corresponding knowledge and skills and should be done by qualified professionals only. Electrical devices are sources of different hazards - electrical shock, skin burn, fire, etc. A DVD laser is a source of different hazards including eye, skin, fire hazards. This post is just a description of the problem in my particular case and not a recommendation for anybody on what to do and how to fix the problem whatsoever. The description is provided for informational purposes only, I bare neither responsibility nor liability and do not accept any claims for any injury and damage on your side.

A couple of days ago my Samsung home theater HT-X40 started periodically shutting down with "Protection" message. Resetting with "Stop" button pressed for 5 seconds made it forget all settings but did not fix the shut down problem. From the cool start it took about 20 minutes until it switched off for the first time and 2...3 minutes after re-powering while it was still warm. That behavior clearly indicated a problem depended on heating.

A promising thing was that all speakers were working fine every time when the theater was on. The fan on the rear side was working OK, air flow was relatively hot, but it was difficult to judge by that. Testing the speakers did not show any problem - each of them had normal resistance about 6 Ohm. Inspecting situation inside the theater I found the following problems on the speaker driver board (marked correspondingly in the following picture - click to see it in whole size):
  1. the output driver heat-sink was very hot,
  2. inductors corresponding to the central speaker were untouchable (burning hot),
  3. 0.47 uF x 100V filtering capacitor in the central speaker channel had a visible crack on its body.
Test of the unsoldered capacitors clarified that 5 out of the 6 caps had good insulation (infinite resistance at 20 MOhm multimiter range) and only the one with visible crack showed 12 MOhm under the same measurement conditions. Each of these capacitors is connected between the two wires going to the corresponding speaker (in parallel to the load). It was probably happening so that under higher temperature insulation resistance significantly dropped down from the 12 MOhm to a value comparable to the main load, in its turn that increased the temperature more. The temperature kept increasing until the protection switched off the power.

For the first step I decided to exchange only that obviously broken capacitor and see if any other problem would surface after. The original capacitor was 0.47uF, 100V, film type:

I was lucky to find a cap of 0.47uF, 250V, same film type in an old modem. This is the board after replacement:

I intentionally distanced cases of the capacitors from the inductors on the board, because the inductors could be that heat source which helps to damage the caps. Since I had assembled everything back together the home theater has been working normally. In addition I increased the gap under the home theater by sticking 4 pads usually used on furniture legs to protect floor from scratches:

Temperature of air flow from the back panel fan has become significantly lower comparing to that time when the home theater was failing.

Technical Note
From many comments I can see that there is an interest in deeper technical details related to the problem. Here are some useful references:
  1. Class D Amplifier describes principals of operation;

  2. Class D Audio Amplifier Output Filter Optimization - the application note explains why output LC filter is required (in the beginning of "Output-Filter Design section). The reason is EMI (electro-magnetic interference).

  3. 2 x 210 Watt STEREO DIGITAL AMPLIFIER POWER STAGE - datasheets for TAS5162, power amplifier from Texas Instruments with examples of typical schematics. It is probably not the exact power amplifier by part number from the Home Theater, but it's of the same class-D.

Long story short: Nowadays most of audio power amplifiers utilize Pulse Width Modulation (PWM), so called class D amplifiers, because of very good about 90% efficiency. PWM uses higher frequency Fpwm (100kHz and higher) comparing to the sound frequencies and the pulses have fast edges. That's why the output signal besides the sound frequencies also has Fpwm and bunch of its harmonics. The output low-pass filter (here built as passive LC) is needed to block Fpwm related frequencies inside the box - without the filter the wires going to speakers will irradiate these frequencies and may interfere with other electronic devices. Say, without such a filter you would still hear correct sound (probably with unnoticeable distortions), but some electronic equipment around can be affected (anything with "wireless", "radio", "sensitive", "low noise" characteristics is in the list).

I hope this technical note can help to understand better what's going on there and how to deal with the problem.


I'll keep updating the post.

44 comments:

Anonymous said...

Great article that helped me out tremendously.
Ok, I had a cap that actually blew up. I have a couple questions.

How do I find a new .47uf, 100v or higher file cap? I tried on internet and cannot find one.

Also, do I actually need to remove the "board" from the home theater to solder it on?

Lmk,

Will

SVN said...

Hi Will,
I actually found them at Digikey for the case I could not find any around: http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=495-1162-ND
Or you can search yourself - Digikey has a very convenient searcher. First ask "capacitor", then "in stock", film, 0.47uF, 100V (or more if you like), "Through Hole", "bulk" - that will give you a list of available caps. I would choose those with higher working temp up to 125C and 7.5mm distance between leads. www.mouser.com has this type of caps too. Radio Shack does not have exact value, it has 1.0uF: http://www.radioshack.com/product/index.jsp?productId=2102515 - so you can connect two such caps serially, it will give you pretty close 0.5uF in total. Problem with the parts that they are cheap themselves and delivery can add significantly to the cost.
I hope it helps.
Cheers,
SVN.

SVN said...

Regarding soldering a cap without taking the board out - unfortunately I can not find a top view picture of the board, but I think it is possible, but on the other hand it is easy to disassemble (just some screws and two connectors) and I did prefer to inspect the board on the other side too.
Cheers,
SVN.

Anonymous said...

Thanks for the info guys. Short of wiring this thing to operate from the frig it was destined for the trash. Got mine to run by physically reversing the fan. Will replace the cap, thanks for the value of the cap and procurement options. Working on this stuff today is real challenge.

Anonymous said...

I had this exact same issue. I decided to just remove the two damaged capacitors completely and I physically reversed the fan. Now my unit works perfectly and isn't overheating or turning off over and over again. It's been 3 weeks now with no problems at all. My system even sounds a little better now but that could be because I re-wired the whole system before I opened the reciever up and discovered what the actual problem was.

SVN said...

I was thinking about reversing the fan too. The idea is clear: bring outside cool air right to the hottest part of the device. The drawback of this approach, as I can see it, is that the air passing through the speaker driver radiator, which is pretty hot at full load, would get hot too and then it would transport the heat to other areas of the box. My concern was that performance of some other parts like DVD player can be sensitive to overheating, so that time I decided not to use reversing the fan. Nevertheless it is interesting to keep different solutions in the list and thank you for sharing your experience.

Regarding the caps - it's a great info about using the system without the caps, since you confirm it can work fine,- however I would still consider finding new caps for replacement. I can drop some technical words here, but just from a common sense: hardly they are some accidentally happened caps, if the developers of the system could ignore them they would do it by sure just to reduce the cost.

Mauricio KS - mauricio.kojo@bol.com.br said...

Muito Obrigado pela dica...

Ajudou-me muito a solucionar o meu problema.

Levei o Home à assistência autorizada samsung e queriam cobrar R$ 218,00. Recusei e resolvi sozinho (com sua ajuda) por R$ 1,20.

Muitíssimo obrigado...

Mauricio KS
Guarulhos - São Paulo - Brasil

SVN said...

Yes, ironically repairing can cost more then item retail price.

Anonymous said...

My samsung got same problem,all capacitors looks okay , but the fan is not running at all.
i opened the case leave it for whole night to cool
next day same error come up , any thoughts?

thanks.

SVN said...

You noticed that right - in your case the overheating protection switches it off most likely due to the fan failure. It’s either the fan got broken or kept from rotation by an obstacle or fan controller (I think it is not directly powered fan, it is regulated by a controller, but I am not positive) or connection problem between the fan and the controller. It is necessary to find out what’s causing the problem with open case and for some tests with powered device. The best would be to ask someone with professional knowledge in the area for help: electrical or electronic technician or engineer – they are able to figure out the problem and fix it on their own.

Regarding material cost estimation (excluding price for the work):

1. If anything wrong with the fan wires or connector it would be easy to fix – cost is $0;

2. If the fan is not working – a new one would cost about $10;

3. If the problem of the fan powering is located on the board there are some possibilities:
a) It can be, for example, a bad soldering or derbies short circuiting anything in the fan controller, but nothing has been really damaged there - $0 to fix.

b) Fixing the fan controller, if it’s broken, may cost about $10…$30. Or it can be bad connection from a temperature sensor to the fan controller. In all cases of this kind I would consider another possibility: simply to find proper power lines on the board (it's, probably, +12VDC – should be double checked) and power the fan directly. Then the fan will not be controlled anymore but it will do the cooling job well. Cost of the approach would be $0.

I hope it can help.

Anonymous said...

Thanks for help,

I removed the ic heat sink , saw two of the ICs
burned inside. Removed the amp board , now using the home theater as dvd player !

don't know i should buy a new set or send to repair.

SVN said...

Assuming that your home theater is out of the manufacturer warranty already – repairing at a service center can be comparable in cost or even more expensive than a new set.

While I'm personally satisfied with performance of my home theater,- when it works it works,- I would not feel right suggesting to spend more money on another problematic known device.
If repairing it by yourself is not an option then it might be better to shop for another home theater of another brand (the problem is seemed to be replicated in some different models of Samsung home theaters of this class).

Anonymous said...

Grate work. Last night my ht-x250 new box samsung swtitch off without any reason. Whan I open whole theatre I found same likein zour case broken capacitoron board. Tomorow I willmake exchange of them. Thanksalot for grate work.

Anonymous said...

Yep, my Samsung HT-X70 went into "Protection" mode due to overheating as well. I smelled electrical fumes coming from the unit. Opening it up is very easy, 6 small phillips screws and off comes the top. One of my capacitors was fried. I just pulled it out and yanked out the pins as well that connected it to the motherboard. I didn't replace the capacitor because you don't really need to. It rund fine. I also pressed/pushed the remaining capacitors away from the line of solenoids that get hot in order to protect them from overheating. I also reversed the fan (not sure if you really need to do this) it is running a little cooler now. However, the fan is makin slightly more noise and is annoying at low volume levels so I may go back in and switch it back. This article saved the day. The unit works perfectly now. Definately an inherent design flaw.

Anonymous said...

ht-x250 is small little s.hit. Like I say ater I change capacitor on board and switch on HT working ok for 2 week. PROTECTION come up again and like before I open box and decide to move all capacitor and install new one. Now situation is little dierent bacause oveheating stop and HT working ok. Interesting point is that HT have all of this problem just because design is so bad. If you move your HT in stand up position hot air will go up and cooler will drain them out HT will operate with any problem. I you leave HT to horizontal position problem will come up ater couple month. Capacitors losing own capacity because lot of hot air stay inside of box. After couple month when they change capacity HT start owerheating and PROTECTION come up. For now I install all new capacitor inside box and box is in horizonal position and work ok. Idea for integrating this capacitor is just to keep peak of voltage from amp in lowest level like some safe guard for speaker. If you open box and found broken capacitor I think is the best to find 6 new and change all of them. If you not have store, similar you can find in old PC modem just with bigest voltage but they will do work.

SVN said...

Sad to hear that you had a longer struggle with your HT. Definitely, all broken capacitors should be replaced - even one failing would keep the system overheating. The easiest, as you mentioned, would be to put all new caps. In my case I had to test them all to be "sure" - it seems to be working; at least my HT is still doing its job well.

Regarding the choice of the caps - please, be careful. They are rated both in voltage and working temperatures. In principal higher voltage rating may help a capacitor to withstand longer at higher temperature, but still dielectric in the cap will be degrading if it is overheated and long term performance again will be under the question. It's better to choose caps by working temperature if one wants to buy new caps or/and reduce their heating what I did in my case.

Anonymous said...

We had a lot of lightning at the house and my HT-Q45 shut off. Now it will only power back up for a second before shutting back off. The fan comes on and the carousel spins, and that is all. I opened the case and couldn't see any visible damage, could it be a similar issue?

SVN said...

It’s a pity many things can get damaged by lightning - not just what the post is about. Usually a destructive pulse comes through long wires as home AC power, TV and phone cables. I can imagine that electromagnetic pickup on any long wire (as ones going to speakers, for example) can be strong enough to damage connected electronics.

To reduce the risk I made all the connections through a surge protector. When a thunderstorm with severe lightning is coming closer, I still prefer to shutdown all valuable electronics and unplug all the cables.

Regarding to your particular case, if you had a surge protector in use, when it had happened, you probably can claim for compensation if the manufacturer of the surge protector promised any (not sure how it works in reality). Repairing, if it comes to that, should be done as usual from checking powering, then one block after another… When there is no clear indication of a problematic place, the process can take a while. Unfortunately, from the cost/time point of view, repairing can be more expensive than the retail price of the new device.
I hope it can help you to take a right decision.

Thomas said...

The receiver feels very solid and has very good build quality. It is not too heavy for a receiver packing 95 watts/channel and does not get very hot at all, even after a three hour marathon watching Lord of the Rings III The Return of the King. I particularly like the quick selection buttons that are like macro buttons you can program for events such as watching a dvd/blu ray movie or listening to the radio or a cd etc...

Anonymous said...

newbie doesn't know anything about electronics but armed with the information provided if i got the part how hard is it to install the capacitor? noticed it was a 'pass thru' but don't i have to use some sort of adhesive to keep it from moving?

SVN said...

In this particular case the caps are of through-hole type. If you're curious about terms here are some references: http://en.wikipedia.org/wiki/Through-hole_technology and http://en.wikipedia.org/wiki/Surface-mount_technology

For the repairing discussed in the post it's necessary to unsolder the broken cap(s), clean up the holes, and then solder the new cap(s). For that it's enough to have a soldering iron and some solder with flux (available at RadioShack, for instance).

Soldering requires some skills, but they are not so difficult to learn. The question is whether you really want to go through all that just for one occasional fix.

The best, I think, would be to find someone who's already experienced in working with electronics, soldering, aware of related hazards and safety techniques, and has all necessary equipment. There should be people like that around – ask neighbors, friends and friends of friends. It would be useful to find someone experienced also if you have stronger interest in electronics - you would quickly grasp many things which would be more difficult to explain.

I hope it can be helpful.

JD said...

Hello, thanks for the useful guide. I was just wondering whether this capacitor is the right type?

http://cpc.farnell.com/1/1/12468-capacitor-0-47uf-100v-mks2-0-47uf-10-100v-wima.html

SVN said...

Yes, JD, the cap is right. The only thing is different lead spacing, it's 5mm. With the original one it is bigger – you can double check it. In this case you'll need to bend the leads to install the new capacitor - not a big deal, though.

sandy said...

Hi I Have a Ht-X40 with the it shutting off and the protection thing. ˆ opened it up and two on the inductor caps were off there post. First is this fixable, Can i just glue them back on. Where can i find a replacement inductor. This is item number #2 in your picture. Saw no visable cracks on the capacitors.

sandy said...

More.. info Under the metal inductor caps are coils of wire wrapped around a post and look undamaged.

SVN said...

Hi Sandy, there can be some possibilities in your situation.

1) The inductors are damaged by short circuited windings. It can be difficult to see any indication of such a problem by eye. You can look closer at the windings and if you're "lucky" you may notice a place changed in color by overheating. The best way to check inductors is to use L-meter. Damaged ones would have almost 0 inductance - comparing to a good one would give an idea what value to expect. It is trickier to detect the problem when the windings become short circuited only at high temp.
How to fix: I don't know exact part number for the inductors and don't see anything close from Digi-key and Mouser. So I would try to get a wire for inductors and transformers of the same or slightly bigger diameter and corresponding temp rate, and then re-wind the inductor with exactly the same number of windings.

2) The inductors are fine, just lost their covers. It's OK to glue the covers back. First, clean up the surfaces from old glue if there is any left to minimize the slot between the adjacent parts. Then glue them together using any kind of thin glue which can tolerate the temperature. For instance, "super glue" is thin and strong but I am not sure about its thermal properties. There should be a suitable type of epoxy. Also you can check out adhesives for car engines, they should be temperature tolerable.

3) The inductors are fine but the corresponding caps are broken. The capacitors may be broken even without any visible damage. Check them as I described above and replace if necessary.

I hope it can help you to solve the problem.

sandy said...

Follow up: I removed the inductors and found the discoloration you talked about. I hooked it back up without them until I get the new parts or fixed them. So the center and front left speakers are not working so I moved the center speaker to the right plug in position. So for now I have the center, sub woofer and the two rear speakers. Not bad, but not 5.1 anymore. Thanks for your help.
P.S. Thanks to the internet and people like you I have saved money and stopped throwing good electronics in the land fills. I changed the coolant in my 51" projection TV saved $$ and brought it back to brand new. Found out how on the internets....

Brett Lowrey said...

My Samsung HT-X40 powers up, says "Hello", then "Loading", then "Protection" and then powers down immediately.

I cracked it open and all the capacitors look like they're in good shape. Could this mean the fan is blown?

I noticed the fan does not run in the 10 seconds it takes to power itself down... Did any of you notice if your fan would at least spin up before "Protection" was displayed?

SVN said...

Hi Brett, in my case the fan spun before protection shut down but time to shut down was minutes not seconds. I double checked my HT yesterday evening. The fan does not start running immediately after the power switched on. It behaves as the fan has a controller which gets a signal from temperature sensor. In your case HT shuts down too quickly to expect that temperature inside has reached the protection threshold.
You can check the following:
1. Switch on the HT with open cover (for your safety do not forget to keep yourself away from the HT guts) and check how long it takes to shut down. With open cover it's supposed to take longer since cooling is better. You can repeat the test with unplugged speakers and see if it makes any difference. If it takes the same 10 sec to shut down, then most likely it is a failure somewhere on the path of protection signal from the temperature (or any other related) sensor to a shutdown execution circuitry. With power off you can look closer at the board if you can find any indication of a problem: short-circuiting small debris, a burned spot, etc. Let me know what you get out of the test and I'll try to figure out what could be wrong.

2. You can check the fan separately - there is a question and answer above about debugging fan problems.

Good luck!

Anonymous said...

My HT-x20 was doing the exact same thing going into protection every 20 min.Not having a multimeter to check the caps i took a chance and replaced all six of them.Buy the way they all looked perfect no cracks or marks of any kind. Its now been running fine for 2 hours since replacing them :-)

Anonymous said...

I already changed all the caps for 0.47 uF 1KV, but the system keeps saying fan check and it turns off, I don't know what else to try

SVN said...

Yes, there can be other things got broken. If it complains specifically about the fan you should check it: whether it rotates or not. Try to replace it or test it aside from the HT.

Stangman68 said...

i have the same proble with my HT-X40, i took cover out and i saw the resistor R97 is burning, somebady know what type of resistor is it? i can see the colors...
ramos.efrain@gmail.com

SVN said...

Sorry, Stangman68, for delay - I'm traveling now. Anyway a picture of the area with the resistor could be helpful. I'll try to reply as soon as I can get internet connection at the next stop.

Martin said...

I opened mine up , 2 of the caps had burnt to a crisp. I replaced the 2 caps but now I have no sound and the fan is loud and always on. Should I replace all 6 caps?

SVN said...

Martin, you can clean up the board thoroughly at that area if you have not done yet. Then
1. double check that all wires on the board around the burnt out caps are OK, no cracks in copper.

2. unsolder all the caps and try how the HT works without them. If you get all channels working, then you can install new caps. It's a pity if some channels still don't work - there is a problem with some other parts.

Martin said...

ok ,thanks one more try . The sound worked ok before i removed the 2 damaged caps. I've fixed things before and this appeared easy.

bardo said...

Fan probs continue'
No dc to fan. What could cause this?

bardo said...

Try this again
Same problem,protection comes on after boot up and shuts down. Fan does not turn on. Voltage at fan molex plug reads 0.3 volts( too low)
Any ideals?

SVN said...

Hi Bardo, sorry, I'm still traveling, so I can not reply quickly. The problem is that protection can be caused not only by the output buffers, as with the burnt out caps, but by some other circuits.

One possibility is that a temperature sensor and related circuits are malfunctioning, but I don't know where they are located on the board. It's a pity I don't have schematic for the HT.

Regarding the fan powering you can try to track the traces from the fan connector down to fan controller and look at the area around it closer. But again the controller can be fine: the HT just goes into protection shut down too fast so the fan controller does not have time to get switched on.

bardo said...

Well turns out I had a warranty till 2011.
I do have the Schematics if any one is interested Thanks for the help

Rama said...

Thanks for the great article. I needed help with getting together my whole house audio and I found many great resources on the web.

SVN said...

If anyone has a schematics, it would be helpful to get a link to it.
You can publish it on your web-site or store at one of many free servers as
I mentioned in http://craftsman-hambs.blogspot.com/2009/10/free-web-storage-for-files.html

Anonymous said...

I just cut the case open and put a 4 inch computer fan in the top.

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