DrKarma
New Member
Two days ago I was given a faulty HTR-5630 AV amplifier. When I asked the lady that gave it to me she said (paraphrasing her words slightly to fit the crowd better) that when she used it, a few seconds after activating any of the DSP effects it would turn off.
Now. I do play around a bit with amplifiers as a hobbyist, but then we are talking vintage stereo amplifiers where I kind of can follow what does what. When it comes to modern amplifiers I haven't done any work on them so far...but here I have a free amplifier that otherwise would go to the electronics recycling bin.
So when I got home off to hifiengine and download the service manual.
Turned on the amplifier and it started - played music without any problems. Then I hit the "effect" button and a protection circuit activates and turns if off.
Restarted it and left it in normal stereo mode then it worked until i cranked the volume up a bit...then it turned off again.
After some playing around with the menu settings I noticed that I could activate/de activate rear and centrum speakers (which were activated). After that, no problems anymore with stereo- or effect-mode.
So far so good. Works well as a stereo amplifier, but not when activating surround speakers.
I started to measure for open or shorted speaker terminals and when reaching rear left speaker terminal, the DMM in continuity mode beeps.
Looking briefly at the schematic from the service manual I thought it was the STK402-120Y IC (IC302) that was shorted for the rear left channel and that it would cause the shorted terminal.
So I ordered 2 aftermarket STK402-120Y (ordered two since this would not be original so figured that I would need to change both IC302 and IC303 to keep the Left and Right channels with same amplification.
Now....this was the lazy approach - mainly because I came to the conclusion that the IC was faulty without actually measuring it. as the IC302 is hidden behind an additional PCB can't reach it with my probes.
When I have cleared my desk after recapping another amplifier - I will open it up and dismantle the yamaha so I can do better troubleshooting.
But right now I am actually thinking that it isn't the STK (IC302) that is the problem after coloring the paths for the IC302 rear left channel.
How would you experienced people approach this troubleshooting - am I on the right track?
I have made some blue squares in one of the attached files (schematics.pdf). These are the only areas that I can see that could cause continuity for the rear left channel.
Now. I do play around a bit with amplifiers as a hobbyist, but then we are talking vintage stereo amplifiers where I kind of can follow what does what. When it comes to modern amplifiers I haven't done any work on them so far...but here I have a free amplifier that otherwise would go to the electronics recycling bin.
So when I got home off to hifiengine and download the service manual.
Turned on the amplifier and it started - played music without any problems. Then I hit the "effect" button and a protection circuit activates and turns if off.
Restarted it and left it in normal stereo mode then it worked until i cranked the volume up a bit...then it turned off again.
After some playing around with the menu settings I noticed that I could activate/de activate rear and centrum speakers (which were activated). After that, no problems anymore with stereo- or effect-mode.
So far so good. Works well as a stereo amplifier, but not when activating surround speakers.
I started to measure for open or shorted speaker terminals and when reaching rear left speaker terminal, the DMM in continuity mode beeps.
Looking briefly at the schematic from the service manual I thought it was the STK402-120Y IC (IC302) that was shorted for the rear left channel and that it would cause the shorted terminal.
So I ordered 2 aftermarket STK402-120Y (ordered two since this would not be original so figured that I would need to change both IC302 and IC303 to keep the Left and Right channels with same amplification.
Now....this was the lazy approach - mainly because I came to the conclusion that the IC was faulty without actually measuring it. as the IC302 is hidden behind an additional PCB can't reach it with my probes.
When I have cleared my desk after recapping another amplifier - I will open it up and dismantle the yamaha so I can do better troubleshooting.
But right now I am actually thinking that it isn't the STK (IC302) that is the problem after coloring the paths for the IC302 rear left channel.
How would you experienced people approach this troubleshooting - am I on the right track?
I have made some blue squares in one of the attached files (schematics.pdf). These are the only areas that I can see that could cause continuity for the rear left channel.
