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Ongoing weirdness with STK350-030

G

Guest

Jan 1, 1970
0
Originally I posted this thread under "Bad audio IC STK350-030":
All of a sudden the left channel sounds "buzzy".
Not a hum, but the audio is broken up... sounds like a bad cap.
But in tracing the signal I came across this IC STK350-030 that is running
really hot... too hot to touch for very long and it's not on a heatsink...
if I run a finger across the 15 pins, when my finger reaches one end of
these pins, the audio clears up for a second before fading out.
============================================

This is in a ~6.5 year old Sony STR-D550Z AV receiver.

So now I received a replacement STK from http://www.audiolabga.com/

It was shipped with a hunk of styrofoam on the pins in a poly bag. I'm used
to buying parts that come with a hunk of conductive foam on the pins, and in
an antistatic bag.... but maybe this part is not sensitive to static. Anyone
know?

Installed it... left channel is back in business sort of, but there is a hum
present which stays the same regardless of the position of balance or volume
control even if volume is at miniimum.

The hum has at least two components. A 60 hz hum and another hum around 400
hz

Also, the volume is too loud too soon. I.E. volume is very high at a low
setting on the volume control.

And the weirdest part is, now the right channel is totally dead.

I get a loud crack if I change the sound field or the input selector

If I touch the right input on the STK (pins 14 or 15) I get a 60hz hum out
of the right channel.

So sounds like the right channel could be ok past the STK, but something
before the STK is now screwed up in the right channel before the STK.

And the left channel works now but has this 2 component hum.

I am thinking maybe the replacement STK is bad?

Any ideas?

Or should I just pitch it and get a new one with DTS etc?
 
G

Guest

Jan 1, 1970
0
Correction- the right channel appears to be ok.

I just had the volume down low so the left channel wouldnt be too loud.

So if I turn balance all the way to right, I get a good right chhannel, and
the 2-component hum out of the left.

The left channel is running now but too loud and has the hum.

That's basically what's up.
 
G

Guest

Jan 1, 1970
0
Also, I can see the left woofer pulling in and out at a varying rate around
1 or 2 hz.

Very strange...
 
G

Guest

Jan 1, 1970
0
Now i found a bad 47mfd 50v cap connecting to pin 14

Radio shack only has 35v...

bah!
 
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