Creative Gigaworks S750

[Agent24]

Re: Creative Gigaworks S750

That crap glue that turns brown and conductive should always be removed, it will go bad later and wreck things.

If you want good glue for replacement, I would go with 'Neutral cure silicone rubber' as mentioned here: http://electronics.stackexchange.com...oid-vibrations

[jnzz001]

Re: Creative Gigaworks S750

Well, that's ez - got plenty of HQ 3M silicones, how about removing the glue - that's chemical or just mechanical stripping and what did you use???

[Agent24]

Re: Creative Gigaworks S750

Well, that's ez - got plenty of HQ 3M silicones, how about removing the glue - that's chemical or just mechanical stripping and what did you use???

Just make sure it's a neutral cure type or you'll corrode things and make it even worse.

lexwalker says he used a screwdriver to scrape the glue off. I think some kind of mechanical removal is the best idea. Chemical would probably damage other parts too.

[lexwalker]

Re: Creative Gigaworks S750

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)

Aye, beware of damaged through holes and always check for connectivity. Even though the solder pad may be still there, the connection to the top PCB layer could be be iffy (e.g. solder touching only) or broken altogether. That's why I've used the "L" wire method connecting to top PCB layer through the hole together with the capacitor leg. That ensures good connection at all times.

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.

You don't have to use any glue furthermore...

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

should I be worried or not just yet?

Yes, clear them whenever possible especially those glue that have turned from deep yellow to darker brownish colors. Sometimes cannot tell from the top of light yellowish glue if there are degraded glue underneath. Thus you need to scrape to check for degraded glue hidden from plain view...

Well, that's ez - got plenty of HQ 3M silicones, how about removing the glue - that's chemical or just mechanical stripping and what did you use???

Just use a flat head screwdriver. Can be a tedious job and sometimes time consuming job. Need to be careful around fine traces as not to accidentally damage and/or break any traces/tracks. That's why I've mentioned avoid using very sharp tools like a knife or blade for most of the cleanup. You can still use sharp tools but only when there are difficult spots (and have to careful not to damage fine traces). The more difficult parts are the places there are small SMD (surface mount) components under the degraded glue (such as the audio controller board). Thus must have lots of patience (otherwise may end up cracking and/or damaging those tiny SMD thingy)...

[jnzz001]

Re: Creative Gigaworks S750

well... my glue came off mostly with film - much copper exposed
never mind

[lexwalker]

Re: Creative Gigaworks S750

well... my glue came off mostly with film - much copper exposed
never mind

Well, no one is perfect. The degraded glue has probably eaten/embedded into the green solder resist layer. Here is another one of my work-in-progress, first image is before cleanup and the second image is after cleanup. This one is a Creative GigaWorks G500 ProGamer, which has some SMD thingies and some of the degraded glue got between the power amplifier I.C (TDA8922BTH) pins. The degraded glue has eaten into the green solder resist layer. The previous repairer did a bad job (was returned to the owner as "un-repairable"). Not only he did not remove the degraded glue but also damaged the through holes for the capacitors (he also re-soldered the original bad capacitors back with many of the capacitors having its legs hanging with a blob of solder and not secured to the board!)..

[Agent24]

Re: Creative Gigaworks S750

well... my glue came off mostly with film - much copper exposed
never mind

You could use something like this: http://www.supremeantennas.co.nz/vie...pray-300gm.php

[jnzz001]

Re: Creative Gigaworks S750

Thank you!

Just wondering about heatsink temperature - I just finished testing it and will be applying the silicone, I noticed the heatsink is pretty hot - may hold a finger to it for a second or two. I guess that would be in the 70 C degree range. Is that normal only after playing a song and not very loud? I can tell it's hotter on the end where 68uF/470V single big cap is so the transistor (?) behind it. The system was on for many hours though, just idle.


??

[Agent24]

Re: Creative Gigaworks S750

I am not sure, but amplifiers and power supplies in general run hot, especially ones without fans.

I assume you mean the big capacitor by itself next to the big row of four? I don't have one of these units so can only go by the photos people have posted here. That is why it's so useful to upload your own.

[momaka]

Re: Creative Gigaworks S750

I noticed the heatsink is pretty hot - may hold a finger to it for a second or two. I guess that would be in the 70 C degree range.

Although each of us has a somewhat different perception of temperature, the average temperature that you'll percieve as nearly burning hot is about 50C-55C. 70C is usually painfully hot and may even cause mild burns in some cases. So my guess would be the heatsink is running closer to 50C if you can hold it. Yes, that probably is more or less normal temperature when playing music "not too loud". IIRC, class AB amplifiers dissipate the most heat when running at 1/3 of their rated power.

[jnzz001]

Re: Creative Gigaworks S750

just wondering if anybody knows of the best compound for ultrasonic washer, I remember some bluish powder from old times, would flux off as a charm and was diluted with water - unlike laquer thinner which you would have to use a lot... rubbing alcohol does not work on any kester rosin flux

[dlduscg]

Re: Creative Gigaworks S750

Hi, I wud like to join this discussion about the s750 and try and get sum insight into my particular problem. Started with no power (no green light). Cleaned all degraded glue and replaced all recommended caps altho only found one 470 cap leaking, checked all suspect components, cleaned boards and reinstalled without input and without external spkrs. Applied power and green light came on and everything appeared normal. When I powered on the audio control unit I got a high pitch (varying intensity) sound coming from the sub. Changing the volume level on the control unit has no effect on the sound. Checked for ground loop without results. Suspect the filter cap on the audio board which I did not replace (1000 mfd 100v), but have not replaced it yet. Is there something I missed?

Well, I've check and rechecked everything I've done and have determined, thru the process of elimination, that the problem is in the audio board which feeds the center/woofer and side speakers; the other outputs work fine, but when I disconnect the ribbon connector from the board, the high pitch sound is no more. I am considering replacing all of the caps on this board. Does anyone have any suggestions before I start replacing caps, like is there something I missed?

[Agent24]

Re: Creative Gigaworks S750

Sounds like something is oscillating perhaps? Try tracing the audio signal to see where the spurious signal comes from.

[momaka]

Re: Creative Gigaworks S750

Does anyone have any suggestions before I start replacing caps, like is there something I missed?

Post pictures of your board here. It's always good to see exactly what you are seeing.

[brogdan]

Re: Creative Gigaworks S750

hello

i had problems with my system, and i replaced the relay

now the power supply is ok, but i have no sound. i can power it up, turn the volume to max but no sound comming from the speackers

i measured all voltages on the TDA ,

on the mute pinof the TDA i have 4.6v so i think it should be ok,
i problem i think it is with the oscillator. i see this system uses external oscillator, and to work with external oscilator i read on the TDA datascheet that the OSC pin should be 5v. that is pin no.7 of the TDA. and on that pin i have olny 1.2 V.

can anyone help with a measurement?

[Agent24]

Re: Creative Gigaworks S750

I have not looked at this thread for a while.

Which TDA chip is this? Model number?

Can you post some good photos of the amp board?

Do you get sound on any channels or none at all?

[brogdan]

Re: Creative Gigaworks S750

here are some photos of the 2 boards

[brogdan]

Re: Creative Gigaworks S750

TDA 8922BTH

And i don't get sound on any channel

[brogdan]

Re: Creative Gigaworks S750

forgot to mention it's GIGAWORKS G500

[Agent24]

Re: Creative Gigaworks S750

I looked at the datasheet (attached)

It seems for an external oscillator input, the 5v means that's how high the signal can go above SGND (signal ground).

You will need to measure with an oscilloscope or look with a frequency counter and see if there is a waveform between 210-600kHz as described. I assume it will be a square wave. When measuring with a voltmeter you will get the average DC value (think PWM effect) and it will not be 5v.


What else have you checked?
Do all the ICs have the correct voltage rails present?
Have you checked the audio input pins to see if anything is going in?
Did you check the MODE pin 6 to make sure the ICs are not in standby or muted? It should be above 4.2v for normal operation.