No Front channel

[bogart219]

Yellow again,
Man its been a bad last couple of weeks. Everything is breaking down.
Anywho, I have a Sony STR-D911 Stero receiver. I use it with my large screen.
Its the dolby surround. Problem, no output from front speakers. Center and rear channels working ok. Switched front speakers to the rear jacks and they worked. Seems to be in the receiver. Should you be able to read a dc voltage at the speaker jacks on the back of the unit? Any suggestions on what to check? Thanks!

[Krankshaft]

Re: No Front channel

Speakers operate on AC the only way I trace out amp problems is with my scope.

Check the output transistors for the front channel.

[Krankshaft]

Re: No Front channel

Crap I thought I had the schematic but they cut out the actual schematic out of the PDF. It was more like a disassembly manual.

DC on an amp output is never a good thing sounds like a shorted output transistor.

[bogart219]

Re: No Front channel

Crap I thought I had the schematic but they cut out the actual schematic out of the PDF. It was more like a disassembly manual.

DC on an amp output is never a good thing sounds like a shorted output transistor.

Hey Krank, I wasn't clear. I didn't measure dc voltage on those speaker terminals. I just assume being there was a + and - for the speaker wires that it would be a dc voltage. So its ac. I believe the front channel is rated at 100 watts. What do you think the ac voltage should be roughly? I should note that the wires from the small front speakers go to the big woofer first then from there up to the receiver. This was a cheap KLH woofer with two front speakers.
Its work fine for fifteen years however. My center channel speaker is a good one though.I'm going to tear it apart tomorrow. Too bad about that schematic.
thanks!

[Toasty]

Re: No Front channel

Probably an STK type chip amp. Left & right in one SIC.

Do check the speaker conns for a DC voltage. I don't know if yours has speaker protection relays. Does the unit make a "click" before sound comes on? Some are very audible, other are not. Compare the front outputs DC voltage to the other working channels. Usually a DC voltage indicates a blown chip (or transistor).

Toast

[bogart219]

Re: No Front channel

Probably an STK type chip amp. Left & right in one SIC.

Do check the speaker conns for a DC voltage. I don't know if yours has speaker protection relays. Does the unit make a "click" before sound comes on? Some are very audible, other are not. Compare the front outputs DC voltage to the other working channels. Usually a DC voltage indicates a blown chip (or transistor).

Toast

Yes, unit does make click right before sound comes on. Upon more testing, I found that its not the speaker jacks but the Left (white) audio input jacks that has the problem. If I unplug (rca phono jacks), the left one, I get full sound from the right (red) one.
With both plugged in you can hardly hear anything, real faint. I tried it on video 1,2 and 3 with my dvr and dvd player, same problem. The stero radio plays fine. I seen what looked like that stk chip there, a 16 pin. Do you know of any test I can make to clarify this? Its almost like the left audio in jacks are getting shorted out or something. Thanks for any info!

[Toasty]

Re: No Front channel

Has anything changed recently? A new or different player of some type perhaps?

If the stereo radio plays fine, then it's those input jacks, not the audio output. Check for cold solder joints or a broken or stuck piece on the jacks. Are these jacks something that you plug and unplug from often? Could be a problem in the audio jack input circuitry.

Does the stereo still play okay if the player(s) are connected?

Toast

[bogart219]

Re: No Front channel

Has anything changed recently? A new or different player of some type perhaps?

If the stereo radio plays fine, then it's those input jacks, not the audio output. Check for cold solder joints or a broken or stuck piece on the jacks. Are these jacks something that you plug and unplug from often? Could be a problem in the audio jack input circuitry.

Does the stereo still play okay if the player(s) are connected?

Toast

Toast, nothing has changed. With those audio jacks from the dvr & dvd players
plugged in, the stereo works fine, full volume and both right & left channels. These audio jacks are not something I plug & unplug often. I will check for bad solder joints and see what else I can determine and get back with you!
Thanks!

[Toasty]

Re: No Front channel

Ummm... bad cable(s)?? Plug the left in right, right in left, or just use the good channel cable to check each input.

Toast

[bogart219]

Re: No Front channel

Ummm... bad cable(s)?? Plug the left in right, right in left, or just use the good channel cable to check each input.

Toast

Hey Toast,
If I put my ohm meter probes inside the left & right rca jacks for video 1 or 2, I read about 9 megaohms. If I do this on the video 3 jacks (located on the front of the unit), I read about 90K ohms. I disconnected video 3 from the main board then tried it. It appears to work now, however it would cut out now and then. I suspect like you said it could be the cables. Maybe I had two problems. Will put back together and see what happens!

[bogart219]

Re: No Front channel

Just a follow up. I left the video 3 input disconnected and put on different cables. Both my dvr and dvd players sound are working good now. Once more thanks for the support!