Sony STR-DE945 - 'A' speakers suddenly quit, 'B' works fine

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Hi all,

As noted, everything is honky-dory, running optical 5.1 from a few different sources. All of sudden, the speakers just die. No loud listening or anything... just watching the US Open.

Checked all the fuses I could find, then switched the speakers to the 'B' output. They work fine there. Even stranger, on the 'A' setting, NONE of the speakers work... centre or sub. Yet, on the 'B', they all work fine.

Weirder yet, is SOMETIMES, when I'd switch between A and B (with the speakers still on the A side), I'd get a second or two of audio, then it would quit. Maybe 1 out of 10 times it would do this.

Any ideas? It looks like quite the gong show to take it all apart...


The switch is OK, as when I turn it I can hear the little relays doing their thing somewhere in the guts of it. I've seen folks selling them for under $100 on eBay, so maybe I'll keep running it on the B output and if it blows up just get another one... I imagine just taking the thing apart is a $100 charge...

I was looking for something that burnt or melted, but everything visable look alright. Nothing smells like it cooked or anything... maybe some little IC went to heaven...
I am going to hook another pair of speakers to the 'A' side, so I can tell if it is intermittent without re-wiring every 5 minutes. The 'B' side is working great... sounds 'smoother' for some reason.

I'm thinking one of the relays is caput, but I've never switched between A and B before... never had more than 1 set of speakers. I can't see how it would wear out or get dirty... but, now that I think of it, when the unit itself fires up it makes some clicking, so that's probably the relay right there...

It's hard to tell, but it looks like the relays are 2 little blue boxes, maybe 1.5cmx1cmx2cm near the middle (?) I don't suppose these would be a common part to find somewhere...

This is the first Sony thing I ever had break... even my old CDP990 from about 15 years ago still works great. Maybe I can save up and get a new ES piece or something since the 'B' side seems to be holding out.

Any idea where the AC detect would be? I'm guessing right close to where the power comes in? There is no message on the display, and the amp seems to recognize signal coming in, as the AFD knows what's coming in from where.

Thanks for the tips so far,

Joined 2004
Paid Member
Hi fridayfriday,
Could be the relays for sure. Best thing to do is take one out and try to match it up. Before taking it out, play at low volume with speakers connected to "A". Tap the relay with your finger to set if the sounds cuts in and out.

The AC detect cap is in the low voltage supply near a single diode. I go hunting with a 'scope to find a 1 uF with 60Hz ripple across it. I don't think that is your problem at present.

sony de-945

id have to look at the schematic on monday to know for sure but i dont think there is much between the switch and the speaker except for the relay and its diode. it may be the relay (which is probably a 12v relay). i doubt if it is the diode. however there may be a resistor in the path. i will look and try to get back to you. i wouldnt be to quick to buy another one since the unit is not really "broken". if the switch is ok then it is probably the relay or another small part.

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