hi, lex, what do you use to remove those degraded glue, they are very hard, thanks!

Thanks, that's what I think, really time consuming and need patience.

I have another question, are general purpose capacitors OK for the 2 capacitors of 100v 330uf? Since I can't find neither Rubycon ZLJ nor ZLH here. I have Rubycon YXA and NIPPON KMF series.

Nippon KMF are actually 16mm, guess would not fit perfectly. They should be authentic, but I'm not 100% sure.

Looks like I will buy from Digikey anyway.

Thanks for the info!

Hi, lex,

I had someone tried to repair s750 which has small distorted sound for me but not succeed,, I can see one resis blown (R30, R39? can't remember). The guy said once he replaced the blown one, it's good, but after he turned volume up it blown again. What could be the problem? And when I got the power board back, it's missing some components, I guess the guy didn't put them back. Could you tell me the info about R30, R39, R31, D24, R23, R42? Digikey links would be perfect, appreciated.

Chris

Hi lex,

I see in your second repair, the solder pads were damaged, how did you solve this? I got this problem too, they came off very easily. I am trying to repair my another s750 which has a problem have to switch on twice with controller. BTW, do you have any idea what cause this problem?

I just changed 4 big 470uf cap, one of the solder pad is damaged. Now when I switch on the speaker with controller, there is a "don" sound, it's not very lound but not small either, didn't have that before, so I turned it off right way in case cost more damage.

Edited,

I just found information from previous posts, so basically these components like caps are connected on top layer, not the back layer where leads are, right? So I need to connect the leads to the top layer to fix the damaged solder pads problem.

And can I just mount them on the back, so the leads are soldered on the top layer, maybe not the big caps but other small components?

This post has been edited by chrislue: Feb 14 2014, 08:41 PM

Each lead of component like a capacitor is actually connected into circuitry on only one side of the board, am I understanding correct?


Anyway, every time when I switch on the speakers with controller, there is a pop sound, didn't have that before, is this due to capacitors failure to connect? I only changed the 4 big 470uf capacitors.

Thank you.

I just checked the stock caps I pulled out, found out that almost every copper tubes inside through holes have also been pulled out with caps leads.

Looks like I have to use the "L" way to fix them all.

Is there any good way to avoid this? I tried use solder sucker, didn't work very well, so basically I just melt the solder and then pull out caps by force.

Thank you for the info, and good news, I have successfully repaired one of my s750 sets! And I know how to read the connections on PCB now! It had distorted sounds before, I carefully replaced some parts, including blown diodes, one zener, some capsm and one IRF740 connected to blown diodes. Soldering on such PCB especially dealing with damaged pads is a frustrating thing, using L connections through holes, scratching solder mask then create connections, have to be very careful. Anyway, without your help, it couldn't be done, cheers!

I'm going to fix my another set with double switch on problem!
edit:
Got my meter today, looks like D9 is a bad one, no visual damage, gonna replace it. BTW, I also checked the topic on creative forum, they are pretty accurate about damaged parts.
edit2:
Replaced D9 and re-soldered those 470uf caps, everything is OK now. Once I thought I need find new replacement for my speakers, but now I have 2 sets of working S750!

I still have another question, since I haven't replaced other small caps yet. For those you mentioned choosing low impedance and/or low ESR types, how much difference is between a high one and a low one? Like for 100uf 35v, between an United Chemi-Con GXE series 340mA 320mOhm and a Nichicon PW series 555mA 117 mOhm? Do they make a big difference? What's the max acceptable impedance or min ripple current?

Thank you.

This post has been edited by chrislue: Feb 17 2014, 10:54 AM

Bad news, one of my S750 blew again, first time after I repaired it it's OK, played some music for several minutes, second time blew when doing some volume adjustments in windows . I checked it, same parts blew, a R30 resistor blew, turn to black, along with a diode d24 (a 15v zener replaced last repair), no visual damage, other parts seem ok.

What could caused this?

Yes, R30 is a 100Ohms 1/4 W resistor, and the zener is 15v 500mW (1/2 W), should I replace R30 with a 1/2 W? I forgot to mention I also changed a mosfet IRF740 Q4 which is connected with R30 in first repair, I don't know if it is failed this time since I don't know how to check a mosfet. R3 and R32 (0 Ohm resistors) are OK.
I have removed all the glue and replaced all the capacitors, same ones you used in your repair.

From the schematic, I can tell C30 is 220pf 1kv, D16 is 1n4148, but what about C58? 3300pf? what is the voltage?