Creative Gigaworks S750

[Agent24]

Re: Creative Gigaworks S750

You're in luck. I found some (unofficial) schematics of the PSU here: http://www.tgahinfo.homecall.co.uk/S750%20PSU/
Added the lot here in case his website goes down.

[momaka]

Re: Creative Gigaworks S750

but looking at it I realize I should definitely take one of the underside (you mean the part of the pcb that is not covered in components I suppose).

Yes!
However, please try to use a proper camera for the pictures rather than a cell phone camera as blurry pictures are of very limited usefulness.

You're in luck. I found some (unofficial) schematics of the PSU

Nice work Agent24!
Looks like the first thing that needs to be checked are the voltages from the Standby/Auxiliary power supply at connectors CN4, CN5, and CN6. The first schematic lists all of the voltages at the bottom and at which connector (and pin) they can be found. Just follow that and report what results you get. Then we will continue from there.

[Reekk]

Re: Creative Gigaworks S750

Hi!
I just noticed that my S750 only outputted sound on the front and rear channels. No sub/center or side. After some google-ing I found this fantastic site! I hope you can help me =)
After opening it up I found that something had burned/exploded (see fig. 1).
On the other card there seem to be a similar configuration, still intact (fig. 2).
The question is: Do you think it is the same? And what is it? My experience with electronics is limited, and all it says on it is "105".
Is this the same as a 1uF capacitor? Does anyone have any idea of what kind of voltage is required?

Kind regards
Christopher

[Agent24]

Re: Creative Gigaworks S750

Yes, it does look like a capacitor. If it is, it's probably a multilayer ceramic, I would say.

BUT it may very well be a Polyfuse, which would make more sense, considering how it burnt up. Also the silkscreen doesn't show a capacitor symbol underneath it.

Does the silkscreen show a part reference number?
For a capactor this would be Cxxx
For a fuse, probably Fxxx

Try to get a better photo of the silkscreen around it if you can

[Reekk]

Re: Creative Gigaworks S750

I managed to clean the area around the burned one, and it seems to say C40 (attached fig).
So probably a capacitor then?

[Agent24]

Re: Creative Gigaworks S750

Well, it would seem that it was indeed a capacitor, though it's usually only electrolytics which burn up like that.

I'd suspect there is a shorted or otherwise faulty part somewhere else, which took out the capacitor.

[Reekk]

Re: Creative Gigaworks S750

Do you think it would be worth replacing the small capacitor (and the damaged electrolytic one), without finding the other faulty part? This is the only obvious fault I find

Would any 1uF capacitor do?

[Agent24]

Re: Creative Gigaworks S750

You could just replace it and see what happens but I wouldn't get my hopes up that just replacing C40 will fix all your problems. For replacement you should use another ceramic one, or at least something which is non-polarised. Clean off the soot so you don't get more problems (Carbon is conductive!)

The electrolytic next to it you may not need to replace, the sleeve is burnt but as long as the can itself is not punctured, it's probably OK. Should do for testing, anyway.

Before you do though, get the board under some good light, and carefully inspect the other components.

I found this: http://forums.techarena.in/hardware-...ls/1403911.htm

I have begun troubleshooting my s750 sub. The first thing I checked (after reading Shotfires posts) was the yellow 1uF caps (C40) on the amp boards. 1 of them was indeed shorted. I replaced it but it didnt seem to make any difference. So I pulled the power board off and took a closer look. I found a component completely toasted with burn holes deep into it. I am not sure what the component is but the PCB label is TH1 (maybe thyristor). It looks like a large grey disk cap but part of the label on it is burned off so I cant tell. If its not too much to ask can someone check their sub for this component and let me know what the label on it says. All that I can make out is 1310... It sits under the metal frame behind the large yellow box-type cap and bright blue ceramic disk caps.

I would at least check TH1 as well.

These guys also speak of S750 with blown C40: http://forums.creative.com/archive/i...87662-p-2.html
and one of them replaced C40 with a big polyester capacitor: http://img364.*************/img364/8394/dscf0898jc6.jpg

You might find something useful there

[Reekk]

Re: Creative Gigaworks S750

Thank you!
I will look into the links and see if I can find the cause of the problem.

Thank you again, your help is much appreciated!

[jnzz001]

Re: Creative Gigaworks S750

I have replaced all caps on PSU board and it worked as a charm - but only for a while. I think I could hear the relay switching a few times after powering the unit off from the control box. Either way it worked fine then while playing something i could hear a BANG and no more music.

After opening it and diagnosing a piece of Q4 mosfet was blown away, R30 was burnt and D24 (15V zener) was short. Also another switching diode D15 was short - both in S1 circuit...

everything else seems fine...

Any idea if something else besides caps could go wrong by itself - or I just screwed up something while re-capping?

Thanks!!!

[Agent24]

Re: Creative Gigaworks S750

A MOSFET could blow by itself or from the controlling circuitry failing, but if it happened right after you worked on it, it could be that you caused the problem.

Need more info, really. What was the problem in the beginning - why did you replace the capacitors? How long did it work for after you replaced the capacitors? What did you use for replacements?

Photos would also help, especially of the work you did to see if there is anything obviously wrong.

[jnzz001]

Re: Creative Gigaworks S750

They sat in my garage unused since maybe 2007 when they went bad - after a few seconds they would stop playing and just output some distortions at sound peaks at high volume...
I finally got to fixing it - replaced all PSU capacitors with mostly OK stuff - the 4 big ones were SAMXON because I did not really want to pay much more... the rest mostly Japan, Elna Re3 etc. The thing system worked for some good 15 minutes. The only weird thing was after powering off I could hear the relay clicking 1 or 2 too many times... I actually washed the whole PCB in ultrasound washer - with heatsinks and all. Was wondering if it might washed out all thermal paste and if I should re-grease it... Some pads on the big4 went off but it should not be an issue since the holes are metalised and you can solder to it and the pads are still on the other side...
parts incoming, will give it 1 more try


Thanks a lot for your help anyways.

[Agent24]

Re: Creative Gigaworks S750

Did you ensure it was entirely dry before you powered it up? I would be worried about liquid left in the transformers etc, though not sure if that would cause your problem.

Elna is a decent brand but the RE3 series of capacitors are just general purpose ones and are not suitable for use in a switching PSU. You need 105°C Low ESR ones for PSU output capacitors.

[jnzz001]

Re: Creative Gigaworks S750

Hell, did not think of that but I think I waited a few days. I think I will just give it one more go once the parts arrive. This glue gave me headaches...

[lexwalker]

Re: Creative Gigaworks S750

I have replaced all caps on PSU board and it worked as a charm - but only for a while. I think I could hear the relay switching a few times after powering the unit off from the control box. Either way it worked fine then while playing something i could hear a BANG and no more music.

After opening it and diagnosing a piece of Q4 mosfet was blown away, R30 was burnt and D24 (15V zener) was short. Also another switching diode D15 was short - both in S1 circuit...

everything else seems fine...

Any idea if something else besides caps could go wrong by itself - or I just screwed up something while re-capping?

Thanks!!!

All of the capacitors? Did you replace every electrolytic capacitors on the power supply board? Also did you cleanup the degraded glue? You could also list down the selection of replacement capacitors used...

Anyway, here is my own guide on replacing those capacitors: Creative GigaWorks S750 7.1 speaker repair, A short guide and info with pictures... (PC Audio) . Do note that damaged through holes can cause havoc especially the main power section. You may want to look at the 0R "resistor" link to bind the halves in that section as well. So far I've had 100% success in reviving these beasts...

[jnzz001]

Re: Creative Gigaworks S750

hmm, yes - all caps on this board, the holes are in a poor shape though, yes.
Will take a look, thanks.

[jnzz001]

Re: Creative Gigaworks S750

wow, what did you use to remove the glue so nicely? My pcb is stripped of silkscreen mask in many places under these caps

[lexwalker]

Re: Creative Gigaworks S750

hmm, yes - all caps on this board, the holes are in a poor shape though, yes.
Will take a look, thanks.

Here are some advise. If the through hole is damaged, then check the connectivity properly. If there are no connections to the relevant traces and components nearby then you need to repair the hole. You can read about repairing the damaged holes in my thread (at Post #21). Also, many of those solder pads especially for the smaller capacitors are very thin and often solder could not be poured nor flow around it properly (encountered this quite often). Do not be deceived by solder on the new capacitor leads because it may be just floating without any full solder contact/connection. Thus after soldering in a new capacitor, do not cut the leads yet. Move the capacitor on the top around and see if the leads on the bottom move as well. If you see the leads move then its bad solder contact and you will need to resolder again. Fine tip soldering iron and magnifying glass may be required. Once the leads can no longer move then can cut them short...

wow, what did you use to remove the glue so nicely? My pcb is stripped of silkscreen mask in many places under these caps

The degraded glue was dry thus its not that hard to remove. This is true for the first few units. You can use screwdriver to scrape them. Avoid using sharp tools like knife or blade, unless there are difficult spots. However if you look at my last reply in that thread (at Post #110), had another unit repaired but had patches of the green solder resist layer stripped off due to very stubborn degraded glue (which is still sticky, wet and more like hardened mud) which ate into that green stuff. Check out the bad capacitor I've pulled out below (from that unit), and you will see what I meant about the stubborn degraded glue (can clearly see chemicals from the decaying degraded glue embedded into the sleeve)...

[jnzz001]

Re: Creative Gigaworks S750

Thank you!

I just booted them with new parts and so far so good.

What I suspect is that a pad (positive one on one of 4 big caps) was hanging in the air or barely connecting.

I was soldering them 1 at a time now and checking connections - the first one was fail and I just had to offset them all and solder from another side (had to leave like 2mm between the cap and the board)

All seems dandy so knocking on wood. just have NO CLUE what GLUE to use... any 2 comp epoxy good?

Thanks a lot for all your help. I haven't done anything in this dept for the last 20 years (almost) - now got sucked in, ordered many tools and all comps for new shiny Pass Turbo v2 amp, learning Altium, guess my old p-cad is no more....

The only problem is I need glasses - I was making PCBs with laquer, nitric acid and mini drill and they looked like retail when I was 15, now just during soldering I noticed my sight is no longer as good.

LOL

[jnzz001]

Re: Creative Gigaworks S750

and these other boards, glue and caps just look atrocious...

should I be worried or not just yet?