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Thread: Successful Repair of s750 with Blown Fuse

  1. #1
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    Successful Repair of s750 with Blown Fuse

    Well here goes my story. I bought my speakers about two months ago, they worked great, right up to the point they died. Sound familiar? We watched a movie, went to bed, got up the next morning and they wouldn't power up. Noticed the green power led was out, checked the fuse and it was bad. Replaced with new fuse and it blew. After reading all the posts of people sending the units in for repair, getting them back and still having problems with them it became obvious that although Creative was repairing them they weren't doing anything about the root cause. I'm an electronic engineer so I decided to void the warranty and try to repair it myself. From my view I didn't have anything to loose. A word of caution here. Unless you or someone you know has a good working knowledge of electronic circuits and how to troubleshoot them please do not attempt to repair this unit. It has voltages in the power supply upwards of 75v. If you touch these it will ruin your day and maybe permanently. Again don't underestimate the voltages or current in this unit or the large capacitors that can store a lethal charge. BE CAREFUL. I begin looking for damaged parts and found none. Then I took an ohm meter and looked for shorted parts in the power supply. I found a shorted MosFET and replaced it. That one blew also, with fireworks. I disconnected the amp boards and using the ohm meter begin comparing the two boards since there almost identical. I found a small yellow capacitor that sits by itself was a dead short to ground. Its across one of the power supply lines. I replaced it and the bad MosFET and now the unit works fine. Two changes I'm making are because the number one and number two enemies of electronic parts is HEAT and VIBRATION. There is virtually no ventilation for the heat the amp generates and it gets HOT. Also mounted in the sub box it is subject to vibration. I've removed the amp and mounted it in another enclosure and have a small computer fan blowing on it. I covered the hole in the sub with a piece of bronze colored Lexan. So far every thing is fine and the amp is operating much cooler.
    Last edited by Kok-Choy; 03-06-2012 at 10:37 AM.

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    Re: Successful Repair of s750 with Blown Fuse

    Do you live in the Netherlands?
    I'd really like you to fix my sub as well, for a fee of course!

    CREATIVE: this man seems to have the root cause of your s750 problems.
    PLEASE take a look at this post and foreward it to your tech-developement team!
    Fixing this problem with a simple fan (which costs 5 bucks) would be nice.
    Last edited by Kok-Choy; 03-06-2012 at 10:44 AM.

  3. #3
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    Re: Successful Repair of s750 with Blown Fuse

    Hi Merquise I live in the US so I can't give you direct help. Most of the failures that cause a blown fuse will be a catastrophic failure of one component which could take other components with it. Fortunately these blown components usually create a direct short. Occasionally they will be open but most of the time they short. These can be found by troubleshooting the unit with the power off (much safer). With an ohm meter and a little knowledge about transistors, (ie Base collector and emitter) MosFets (Gate, Source and Drain) you can find the bad part. This amp uses a switching power supply which takes the incoming AC converts it to DC then converts it to a high frequency AC then back to DC. The reason for the high frequency AC is that it allows the use of smaller transformers and filter capacitors. These kind of power supplies are sum what vulnerable to voltage spikes coming in on the AC line. I would recommend that every one have a good quality surge suppressor between your amp and the incoming AC line. Its cheap insurance. For those who don't want to remove the amp from the sub box just putting a small fan like what's used in a computer would help. You can find the fans at most computer stores and you could use a AC adapter from somewhere like Radio Shack or Walmart to power it. We've been using our repaired s750 for about two weeks now and its on about 2 hours a day for xbox, music, TV, Movies and its still working. If anyone is interested I could post some photo's of the sub and amp box. I also have the pin outs for the Green power cables with the red stripe that go from the power supply to the amp boards. I know that some people out there may not have the money to keep sending these speakers back and forth. But you may have the tech skills to repair them. If we work together we may be able to help each other out. Creative is a good company, they just gotten so big that they seem move slow. That doesn't help us who have paid upwards of $400 for speakers that failed and that cost a arm and a leg to ship back. I also know that there are a lot of units that haven?t failed, but that knowledge doesn?t help the people that have broken ones. One other thing, Merquise they can't add a fan to cool the amp because the hole for the fan would alter the porting for the subwoofer speaker. The physical size of the sub box, the size of the porting hole, and the depth of the plastic tube that goes into the box play a very important role in how well the subwoofer works.
    Last edited by Kok-Choy; 03-06-2012 at 10:47 AM.

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    Re: Successful Repair of s750 with Blown Fuse

    I just wanted to clarify that when I talk about adding the computer fan I'm talking about adding it external to the sub box and it would be blowing on the back of the amp to help cool the back panel which will help somewhat to cool the internal components. I know that there are a lot of designs out there that put the amp in the sub box and they work fine. My response to that is That's great but, It doesn't help me or anyone else with a s750 thats collecting dust. One other thing I want to say is that I am not interested in bashing Creative at all, I like the speakers, I just want to help other customers that my have similar problems so they to can enjoy the great sound these speakers produce.
    Last edited by Kok-Choy; 03-06-2012 at 10:50 AM.

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    Re: Successful Repair of s750 with Blown Fuse

    Hi Shotfire,

    Too bad you're living so far away from me
    I've been trying to read what you wrote but seriously, I have 0 experience with electronics so it's all abracadabra to me :| My plan was to bring the sub to a store around here with a printout of what you wrote and then hope they know how to fix the problem.
    You said you could make pictures, if you could that, it would be a great help as well.
    If it's not too much trouble, please do so and post them here or send them to me via email:
    sasskia_walraven@yahoo.co.uk

    Thank you very much and I think Creative should pay you for solving their big problems

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    Re: Successful Repair of s750 with Blown Fuse

    I already have a 20mm, 2volts fan and I'm gonna glue it to the back of the new sub (whenever it arrives) so I hope my next sub wont die this soon. I will also buy me that thing that works against spikes. Thanks for allt he good advice and help Shotfire
    Message Edited by Merquise on 08-17-2006 05:32 AM
    Last edited by Kok-Choy; 03-06-2012 at 10:50 AM.

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    Re: Successful Repair of s750 with Blown Fuse

    Wow, congrats on getting yours fixed. My first set died one month after warranty. It costs me about $325 to get my replacement set and that died 3 days after the 6 month warranty for the RMA...@_@

    Yeah... I've spent about $750 for two systems that don't work properly. You should try getting Creative's attention so they can finally fix this problem and stop ripping people off. I definitely agree that the speakers sound awesome...when they work. You seem like a very intelligent man in dealing with electronics. Get Creative this info for us all!

  8. #8
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    Re: Successful Repair of s750 with Blown Fuse

    Hi Merquise & JoMaMaz!

    Thanks for the complements. This kind of stuff is second nature for me, I've been involved in electronics, manufacturing, and marketing for the last 40 years (I guess I'm dating myself) anyway, I currently own my own company and have for the last 20 years.

    JoMaMaz I know that Creative personel do read the posts that we place. I'm also sure that Creative is well aware of the problem with the s750's. This kind of problem can be a nightmare for any company selling products. This situation is one that most companys try to avoid at all cost. One of the things that we don't know and probably never will is the failure rate of these speakers. Is it 5 percent or 50 percent I doub't will ever know. Personally I don't care what the failure rate is, I just see a lot of people that have paid money for a system that sounds great. When it works.
    The problem that concerns me the most is that the repaired units are failing also, if you keep sending it in, then the warranty runs out what do you do. For everyone that has taken the time to post about the s750 there are many more who have had problems and not posted about it.

    First I'm in no way affiliated with Creative. Having said that I wanted to describe the delmina that Creative may be facing. The following and all my posts are strictly my opinion based on my experience, I do not speak for Creative nor should anything I say here be directly applied to Creative, its just my opinion from my experience in this business.

    If any company admits they have a defect in their product they are obliged to not only repair the product but also do something to fix the defect. They also should offer that fix to all the systems they have sold. This could end up being a huge expense for the company. The consumer view is "Who cares what it costs the company I want my speakers". The company view may be that its cheaper to repair the item than to provide an actual fix for the problem. Problems like this have actually put companies out of business. I use a lot of Creative products, I have Audigy 2 cards in all my computers I have a DDTS 100 (Which I think is a great add-on for the S750s When They Work). If Creative decides that heat is the main problem how do they fix it. You can't just add a fan to the sub box because it'ss a specifically designed acoustic enclosure. If you make a new box to remote mount the Amp you open up a lot of other problems. Just getting the Electrical Saftey certifications needed from the Canadian Standards Association (CSA) and or there American counter part Underwriters Laboratories (UL) is expensive and time consuming. The subwoofer speaker is hard wired to the amp board so the wires either have to be unsoldered or cut to enable the ability to remote the amp. I really don't see an easy way that Creative can design a way that the consumer would be able to do this in there house, what that means is that every unit would have to be sent back for the upgrade, now that's a nightmare for everyone, us and them. They can't offer us to return the speakers for a better set because these are already the top of the line. If there working on a fix they can't tell us because the very next question we'll ask is When? and because of all the issues they may not even know when, and if they give us a date and don't meet it because of something out of there control, "Well Here We Would Go Again". I'm not at all taking there side, it took me a fair amount of time and research to be able to fix mine. Trying to fix something like this without a schematic is about like driving from New York to Los Angles without a roadmap, you just keep heading west and hope for the best.

    I apologize for the long posts, but I don't know any other way to say all this. I hope some of you find this information helpful.

    I'll be doing some actual temperature measurements this weekend and I'll post my findings. Also, I'll provide some more technical information.

    Maybe Creative will find a creative way out of this for all of us. (LOL) Hey, my kids thought it was funny
    Last edited by Kok-Choy; 03-06-2012 at 10:48 AM.

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    Re: Successful Repair of s750 with Blown Fuse

    Well Shotfire this is what my solution is:
    Creative will send me a new sub in about 2 months. In the meantime I brought my old sub to an electronics store with your text added about what was broken in your sub. They will fix it for around 30-40 bucks and it will take about 5 days.
    From that time on I have virtually 2 subs so the next 2 years whenever one of those is broken again I will ask for warranty.
    Also, over here in the Netherlands we have client protection in a way that says that if an apparatus that is out of warranty, but dies within a time wherein a customer can assume that apparatus should still be working, we still get warranty. And that also applies to international firms who sell in the Netherlands. (e.g. if a washingmachine dies after 3 years, while you normally assume a washingmachine should last a minimal of 5 years, you get warranty).

    Look.. my problem is not that I can't afford a new set, my problem is: a) I have to do wait 2-3 months, and b) a company should not sell defective products. If they know a set has problems, stop selling them and make a version 2.

    For once I would like to see an official representative of Creative, and I mean a person with electronics know-how who can call the shots, reply on one of these forums.
    Me repairing my S750 with 3rd party help, putting the inside of the sub to the outside. We call that 'beunen'.
    Like bringing my Mercedes to some hillbilly garageguy in Hoboken USA who uses chewing gum and ductape to fix my radiator. Sure it works and it probably will keep working but it still is slumpy work (I hope slumpy is a word, if not it means: beunen!)

    My worst fear is that I finally get my new sub, then my remote pod breaks down or something and I have to wait another 2 months for a replacement. If that happends then I loose my consumer trust and thats the worst a company can happen I guess. Problems are bound to happen with any product, stuff always goes wrong and there is no problem there. If they replace it within 5 working days I could not be bothered, but hearing some guy from customer support claim they still have people waiting from March (!!!!) is rediculous.
    Every lan-party I go to people ask me where my S750 set is, and I tell them this story.

    Ah well.. I hope in a week I will tell you my old sub is fixed. Will keep you informed
    Message Edited by Merquise on 08-18-2006 09:26 PM
    Last edited by Kok-Choy; 03-06-2012 at 10:53 AM.

  10. #10
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    Re: Successful Repair of s750 with Blown Fuse

    Hi Merquise
    I agree with you, no customer should have to go to making the changes I have to make this system work. By the way, I hold my breath every time I turn the unit on or off.
    I'm glad you found someone to repair your system. The price you got sounds pretty reasonable I would have expected twice that maybe as much as $100US. If I can help them just let me know. Also if they can fix it please let us know what components they replaced. There are quite a few parts that could take this unit down, it would be interesting to see if there is a common part that is failing.

    Here are two web sites that may be of some help.

    1) a) http://www.svsound.com/products-sub-box-0nsd.cfm
    What I found interesting here is this statement. "This high output digital switching amp was designed by SVS in partnership with one of the most capable and largest original equipment manufacturers in the world, Indigo Manufacturing, inventor of the famed BASH subwoofer amp technology. Built in Canada"

    Leads me to believe that Creative may have also partnered with Indigo to "Private Label" the s750. Just a guess.

    b) http://www.svsound.com/manuals/pb0isdjan05web.pdf Towards the end this seems to have a good explanation on how to calibrate your sub.
    2) http://www.bashaudio.com/technologies.htm
    This site has a good explanation of the BASH system and how it works.

    Here goes some more tech stuff:

    There are two amp boards in the s750, they are basically the same except that one of the boards has two of the STA525 amp chips and the other has three. The STA525 device has two channels of amplification in it. On the board with three STA525s on it they use one channel from each of the three amp chips to drive what appears to be a tri-voice coil speaker. (Good luck finding a replacement for this speaker if it goes bad and your out of warranty. Doesn't help that Creative refuses to sell replacement parts.)

    This next part I haven't taken the time to trace out. I would imagine that on the amp board with two STA525s that one of them drives the Front L&R and the other chip drivers the Rear L&R. On the board with three chips the unused channels on each of three chips are probably used to drive the Sides L&R and the Center channel, this could be verified by tracing out the wires.
    On each amp board there is a STABP0 chip, they call this chip a "Digital Processor" what it does is take a signal from the amp chips and uses it to control the voltage applied to the STA525s. It appears that it does that by controlling a "Buck Converter" circuit that is mounted on each of the amp boards. The ideal is to maintain a constant voltage to the STA525s. There are several advantages to this that affect the quality of the sound and the physical size of the power supply.

    If you compare these speakers to others you will find that there is little or no background noise at high volume levels and the sound is very clear. If your watching a movie in 5.1 you probably find your looking around the room at times thinking that the sound you heard came from something in the room and not from the speakers.
    This is what I believe are the pinouts for the Green cables that run from the power supply to the amp boards.

    Please verify this yourself before doing anything. I'm calling the wire with the red stripe pin one.

    1) Positive Voltage Supply 2) Negative Voltage Supply 3) Positive Rail Tracking 4) Ground (This ground only applies to the amp boards and the amp side of the power supply) 5) Negative Rail Tracking

    The Data Tech Sheets for the STA525s and the STABP0s are readily availbleable on the internet.
    Merquise, what is a "lan-party" I'm either to old or live in the wrong country to know what this means.
    Thanks
    Last edited by Kok-Choy; 03-06-2012 at 10:57 AM.

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