Sony STR-DB940 pulled back from the brink

[bklanecky]

Re: Sony STR-DB940 pulled back from the brink

Hey guys.

I found this thread through a Google search, and it sounds like I've got exactly the problem being described here.

I pulled off the bottom access panel of the receiver, and found the points noted in the picture. Thing is, they looked just fine.

I'm no expert on electronics, and I've never soldered anything before. I would consider myself very mechanically adept, so I'm sure I can do it, but I just wanted to be clear on what exactly it was that signifies that a spot needs to be re-soldered. Is it kinda flopped-over? Brown? Black? I couldn't find anything that would set any of those points apart from any of the others in terms of how they look.

Any advice would be greatly appreciated.

[Agent24]

Re: Sony STR-DB940 pulled back from the brink

Solder joints should be smooth and shiny.

Bad joints can be dull, cracked, or otherwise don't look good.

If you search Google images for 'Dry solder joint' or 'Cold solder joint' you can see many photo examples.

[notorious]

Re: Sony STR-DB940 pulled back from the brink

I have a Sony STR-DB940 which seems to have a problem with the center speaker.
it seems weak and is not as loud as the other channels. i done a reset and even tried increasing that channels db but it still is not right. I am using a optical cable to xbox 360 ps3 and pc and the result is the same. i have tried another cable and even another speaker and no improvement. i noticed furball got a 50% better result when he soldered the relays. do you think I should attempt this?

[Agent24]

Re: Sony STR-DB940 pulled back from the brink

Yeah sounds like you should definitely have a look!

[honourablegeorge]

Re: Sony STR-DB940 pulled back from the brink

I'm sat here listening to my Sony 940 amp that's back from the dead after a little bit of soldering - many thanks to the people on this thread for the advice & pics.

[pukka]

Re: Sony STR-DB940 pulled back from the brink

fixed mine too based on the photos and description on this forum. many thanks to all as i'm happy to not throw away a 10+ year amp that otherwise was still working very well.
cheers

[stef]

Re: Sony STR-DB940 pulled back from the brink

bringing this thread back to the top, i dont know if this is more or less the same problem,
im only getting sound from one speaker in 2 ch mode the other speaker just makes a low hiss with barly audible speech or music
ive tried swithching speaker wires over ive tried using one speaker and i found that both left and right channels are working but when connecting both one speaker is way louder than the other
ive even tried another set of speakers

[Agent24]

Re: Sony STR-DB940 pulled back from the brink

Rework the relay solder joints and I guess you'll find out if that's your problem or not

[RobBerry23]

Re: Sony STR-DB940 pulled back from the brink

Been having a problem with my center speaker for a while now, so cracked out the giant soldering iron, could definately see some signs of a dry solder, so solderered a fair few of the joins on the main board,

All working perfectly now

Thanks very much guys!

Rb

[Longbow]

Re: Sony STR-DB940 pulled back from the brink

Taking a more general look at this type of problem might help. This model appears to have lots of loose connections on the relays. Speaker relays in any amp can be intermittent or faulty. If you have a worn out relay, tapping it will make the output crackle or become intermittent. But there is more to it than just a bad joint. One reason the solder may have failed is that the relay contacts are worn out and are generating enough heat to loosen the solder. Replacing the relay is always a good idea if you're having intermittent operation. Another consideration; the relay is designed to keep ugly amounts of d.c. away from your speakers. Since they don't operate instantly, arcing in the contacts (which makes the relay intermittent) may mean your output dc level is starting to creep up. So if the relay is actually opening up during operation, you will want to have a meter monitoring the dc voltage on the input side of the relay (audio input to the relay). 0 volts d.c. is what you want to see. If the voltage is more than 100 mv or so, the protection circuits will turn the relay off to save your speakers. Just a few things to keep in mind. Relays are quite commonly replaced after some years of operation, even if everything else checks ok.

[Clancyman]

Re: Sony STR-DB940 pulled back from the brink

Gentlemen, brilliant is all I can say, my Sony STRDB940, has been silent for the last year, left in a RACK in my recording studio. I was relocating equipment the other day and removed it form the rack and was about to commit it to the grave when I decided to check to see if there was anything on-line. You guys have inspired me to get out my soldering iron and see if I can breath some life back into what was a great amp. Thanks for the support guys, its communities like this that that are a great source of support. Cheers.
Clancyman.

[Lobo]

Re: Sony STR-DB940 pulled back from the brink

Sounds like a similar problem I'm having with my Sony STR-K840P. The front right and rear left speakers have little to no sound. I've opened it up and had a look-see but never thought of checking the bottom of the board. Thanks for posting this, I'll report back if I find anything.

[PapaRaboon]

Re: Sony STR-DB940 pulled back from the brink

Woop woop!!

I also had a relay issue. The rear surround speakers kept cutting out intermittently. But I have also re-soldered all 24 relay joints and it seems to not cut out any more.

Awesome guys. Great fix.

Thank you all.

[petepluto]

Re: Sony STR-DB940 pulled back from the brink


Yep i have STR-DB940 built like a tank and i love but had the same speaker cut out problems for about 2 years but still kept this baby.
Finally got to get a new amp but wait found this great Forum and read a bit....then a bit more....then ordered a soldering iron online for £6.98 then thought i can do this.......and guess what happened next..............it has worked.......yes....even though i ant soldered since school 30 years ago....its worked...not only that but its like a new amp..powers clean...imaging is fantastic...thanks to all you chaps who gave me the courage to keep this legend amp.....if you are unsure take your time and read what these guys say...there the best.

[dave38]

Re: Sony STR-DB940 pulled back from the brink


mine was doing the exact same thing loss of sound from centre speaker and clicking when ever it wanted to i used furballs image as it was nice big and clear.took no time at all no need to dismantle the amp just took the plate of from underneath and soldered the pins in the image.i did all including the yellow ones and its been 3 days now and it is perfect sound loads better what a great fix many thanks.

[peefybonus]

Re: Sony STR-DB940 pulled back from the brink

Success for me also

My amp developed the clicking fault recently and was ready to replace when I saw this thread.

Removed the inspection panel underneath, and gently tapped the main board with a terminal screwdriver handle - after a few minutes I had located the bad joint. You could see where the joint had come away and after a quick re-solder all is good - so well chuffed!

I still might treat myself to a new amp but good to get the problem fixed.

Thanks to all who have posted in this thread.

[trydowave]

Re: Sony STR-DB940 pulled back from the brink

Just got one of these amps for free with remote and very good quality cables.
The guy said that the Bass channel was dead. Will re-soldering these relays help?

I only have a crappy little 5.1 system (those cheap things you get with dvd players). Can I plug those speakers in to test it? Also. If I do fix it, can anyone recommend what speakers to get. What would suit it?

Thanks
Tony

[Agent24]

Re: Sony STR-DB940 pulled back from the brink

Just got one of these amps for free with remote and very good quality cables.
The guy said that the Bass channel was dead. Will re-soldering these relays help?

It may do. You won't know until you try, though.

I only have a crappy little 5.1 system (those cheap things you get with dvd players). Can I plug those speakers in to test it?

Yes, if they are the correct impedance. Make sure the amp speaker impedance select switch (if it has one) is set to the correct setting.

[trydowave]

Re: Sony STR-DB940 pulled back from the brink

It has an impedance selector of 4 and 8, currently set to 4.

Just wondering. Anyone else who owns this amp. What speakers do you have or what do you recommend looking out for?

Thanks
Tony

[RobBerry23]

Re: Sony STR-DB940 pulled back from the brink

Hi guys,

Having the same problem as most are with this Amp,

I have done a solder re-flow before on the relays and the connector joints,

However the centre speaker is now extremely quiet, when I tap on the unit it gets louder and on the other side it gets lower which is odd, I have tried re-soldering the same relays and they seem fine, I honestly cannot identify where the problem lies on the main board,

Whats the best way to test the amps main board? should I go and buy a tester screwdriver? I did put my finger on one of the connections when it was playing music and it did get louder instantly but gave a nasty shock :/

Re soldered that particular joint but it has not helped. So I kinda need to know how to test each joint.

Thanks