Sony STR-DE305 Left Channel Cutout

[skelbley]

So here's my predicament:

I have a Sony STR-DE305 with an output issue. Occasionally, both channels will output properly. Most of the time however, the left channel is completely absent. I've verified that the speakers and associated wire are not the source of the problem, as well as the toggles for "A" and "B" sets of speakers (I'm also aware that having both toggles activated will yield no output on a given channel unless both sets are connected for that channel).

If it's any help, on the rare occasions that the left channel works I've managed to catch that channel going out and I've noticed that in the few seconds before cutting out there is a decent amount of static in addition to the output on that channel.

I have access to a low-end voltmeter, and am familiar with standard soldering/desoldering. However, I have no idea how to trace the circuit from the speaker, and the underside of the board is obstructed by the case.

Three primary questions:
1. Could this be caused by a blown fuse? I've read that fuses are normally located on the rear of the chassis, yet I haven't found any fuses or a box containing fuses in the receiver.
2. Is this something that would cost more than the value of the unit to have repaired professionally?
3. Are there any great resources on circuitry that start from the ground up?

Thanks in advance for any advice. I would like to learn how to fix this myself (even if it takes months), but I also know my limits and am not going to kill myself trying to figure this out if I'm not sure what I'm doing.

 

[jcoultas98]

Yes, it could be a blown fuse. Could also be any capacitor, or connector on the amplification stage board in the receiver. Try to get your hands on a service manual from a service center. They vary from 5-15 dollars. These will give you the correct voltages, and instructions on how to replace/repair/test the unit. I found quite a few units on ebay for 20-30 bucks. if you get one in working order, you can play with replacing parts from the good one to your bad one. As to your question is it worth repairing it professionally? Nah, the replacement model is about $130. You'd easily spend that just on labor.

 

[skelbley]

Best answer selected by skelbley.

 

[skelbley]

Awesome, thank you very much for your advice. I found free PDF of the service manual for download (http/sportsbil.com/sony/STR/STR-D/STR-DE305.pdf), so I'll check this out and see if I can track it down.

 

[jcoultas98]

good deal! Have fun! You'll be surprised how much you learn.

 

[soundguruman]

So here's my predicament:

I have a Sony STR-DE305 with an output issue. Occasionally, both channels will output properly. Most of the time however, the left channel is completely absent. I've verified that the speakers and associated wire are not the source of the problem, as well as the toggles for "A" and "B" sets of speakers (I'm also aware that having both toggles activated will yield no output on a given channel unless both sets are connected for that channel).

If it's any help, on the rare occasions that the left channel works I've managed to catch that channel going out and I've noticed that in the few seconds before cutting out there is a decent amount of static in addition to the output on that channel.

I have access to a low-end voltmeter, and am familiar with standard soldering/desoldering. However, I have no idea how to trace the circuit from the speaker, and the underside of the board is obstructed by the case.

Three primary questions:
1. Could this be caused by a blown fuse? I've read that fuses are normally located on the rear of the chassis, yet I haven't found any fuses or a box containing fuses in the receiver.
2. Is this something that would cost more than the value of the unit to have repaired professionally?
3. Are there any great resources on circuitry that start from the ground up?

Thanks in advance for any advice. I would like to learn how to fix this myself (even if it takes months), but I also know my limits and am not going to kill myself trying to figure this out if I'm not sure what I'm doing.

OH PLEASE! this is NOT a fuse problem OR a capacitor problem.
Where did you guys learn how to troubleshoot?
From the back of a Cheerios box?
BAD SOLDER CONNECTION OR CRACK ON CIRCUIT BOARD---YES.
DIRTY CONTACTS IN HEADPHONE JACK---YES. DIRTY / BURNED CONTACT ON SPEAKER RELAY---YES.
BUT, it is NOT repeat is NOT a fuse or a capacitor.
Do you need the manual to fix "any" of this? NO.

LOOK at the circuit board, inspect the screw holes. Is there a CRACK extending from one of the screw holes on the board? I'm not surprised. The screws holding down the board are often over-tightened at the Sony factory. This causes the board to CRACK.

 

[jcoultas98]

So mad. I had a sony STRDE90ES that blew a fuse on the left output stage board. There's also no reason it couldn't be a cap, sony was notorious for using cheap caps that completely severs the circuit. Could it also be cracked, or a bad solder, sure. Bottom line, he wants to get in there and dig around. Gotta start somewhere.

 

[Joel Cunanan]

I have the same model as you are. Mine is only a matter reset procedures from the service manual. By the way, here some points to test. try resolder IC701 and IC702. These IC's generate heat during operation and if you notice they don't have heatsinks. That makes the solder to soften and loose connection. That's one point and here's another. When you turn it on. Do you hear speaker relays activate and still no sound? do some continuity test. If it has no contacts? Then try cleaning out the relay contacts by removing them from the board, open up and sand the contacts....