Yamaha TSS-1 Surround Sound Speaker System: Repair

I recently acquired one of these units of non-functioning status. There was good sound through the headphone jack, but no sound through the speakers. I inspected the internals for burnt components, bulging caps, loose solder connections and the usual suspects. As it turns out, the problem is apparently a circuit design flaw causing the unit to be stuck in standby mode. The repair isn’t rocket surgery if you have a few basic tools and a reasonably steady hand.

1. Remove the upper and lower shells to expose the underside of the main circuit board.

Underside of Main Board

Underside of Main Board

2. Locate components R377 and Q312.

3. Note the solder trace between the ‘B’ joint on Q312 going to R377.

4. Using an exacto knife or similar instrument, cut this trace. I found this to be a fairly delicate scraping operation, taking care not to damage nearby connections.

5. Solder a 47k ohms resistor (Yellow, Violet, Orange – any tolerance or wattage will do) across this break. That is, from the ‘B’ joint on Q312 and the joint on R377 where the track used to run. Be sure the resistor leads do not accidentally contact any other joints.

Close-up of the repair

Close-up of the repair

6. Blow out any dust that may have accumulated in the unit and reassemble.

The Entire System

The Entire System

It’s a reasonably good sounding unit, suitable for a computer or mp3 player. It has analog, digital and optical inputs. It’s a 5.1 system with front, rear, center and subwoofer speakers. In dolby pro-logic mode it will run all six speakers even with a two-channel stereo signal. I like that feature because with many systems, the surround speakers don’t function unless you’re feeding it a surround-sound signal. Nice!

True, it’s not audiophile-grade gear and it would have been easy enough to trash it, but then I wouldn’t get the satisfaction of knowing that I fixed it and now someone gets to enjoy it instead of it filling the dumps with things that can be repaired.

Many thanks to mattgill for posting this repair on highdefforum. The original thread can be seen at:

http://www.highdefforum.com/archive/t-11209.html

 

–Kenn

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