Hi Folks,
Long time lurker, finally registered. I like to restore vintage equipment, my most recent was a complete recap of a Pioneer SX-1080.
However, in our living room we have a Sony STR-D3070 A/V receiver. It is circa 1991. Rated at 120 watts per channel, I have it driving a set of Bose 601 Series 3's.
Trouble free all these years, but today we powered it up and the right channel burst some static, then exhibited sounds very close to a dirty volume pot. After static stopped, turning it way up on the right side you can hear the music very faintly at full volume. Turned it back down and left it for a minute or two and random bursts of static would happen.
Left channel is fine.
I switched sources and speaker wires back and forth to be sure. The right channel is dead.
I took it apart and applied Deoxit to the volume and balance pots, no change. I took off the bottom plate and used the butt end of my insulated screwdriver to tap and press all over the main board and all the other boards, and I could get no change.
I have a service manual, and noticed there is this STK-3122-3 soldered to the main board. It seems the job of this STK is to run the power amp outputs.
So I took my meter to the 15 leads of the STK-3122-3 and I found something interesting. Here are the results of my readings presented this way:
Pin#
Schematic Value
Reading
Results:
Pin 1
-0.2
-.282
Pin 2
-0.2
-.306
Pin 3
60.9
69.4
Pin 4
60.6
60.2
Pin 5
-1.1
-1.15
Pin 6
1
1.089
Pin 7
61
-61
Pin 8
0.1
-.002
Pin 9
60.9
-61.4
Pin 10
1
1.071
Pin 11
-1.1
-1.111
Pin 12
60.9
60.3
Pin 13
60.9
60.4
Pin 14
-.3
-.322
Pin 15
-.3
-.290
Note I bolded pin 7 and 9.
I have already ordered a replacement STK-3122-3 but I wanted to ask you experienced people your opinion of what might be happening with Pin 7 and 9 and if this is a failure mode? In your experience, does this show a dead STK?
Thanks for any help.
Cheers!
Long time lurker, finally registered. I like to restore vintage equipment, my most recent was a complete recap of a Pioneer SX-1080.
However, in our living room we have a Sony STR-D3070 A/V receiver. It is circa 1991. Rated at 120 watts per channel, I have it driving a set of Bose 601 Series 3's.
Trouble free all these years, but today we powered it up and the right channel burst some static, then exhibited sounds very close to a dirty volume pot. After static stopped, turning it way up on the right side you can hear the music very faintly at full volume. Turned it back down and left it for a minute or two and random bursts of static would happen.
Left channel is fine.
I switched sources and speaker wires back and forth to be sure. The right channel is dead.
I took it apart and applied Deoxit to the volume and balance pots, no change. I took off the bottom plate and used the butt end of my insulated screwdriver to tap and press all over the main board and all the other boards, and I could get no change.
I have a service manual, and noticed there is this STK-3122-3 soldered to the main board. It seems the job of this STK is to run the power amp outputs.
So I took my meter to the 15 leads of the STK-3122-3 and I found something interesting. Here are the results of my readings presented this way:
Pin#
Schematic Value
Reading
Results:
Pin 1
-0.2
-.282
Pin 2
-0.2
-.306
Pin 3
60.9
69.4
Pin 4
60.6
60.2
Pin 5
-1.1
-1.15
Pin 6
1
1.089
Pin 7
61
-61
Pin 8
0.1
-.002
Pin 9
60.9
-61.4
Pin 10
1
1.071
Pin 11
-1.1
-1.111
Pin 12
60.9
60.3
Pin 13
60.9
60.4
Pin 14
-.3
-.322
Pin 15
-.3
-.290
Note I bolded pin 7 and 9.
I have already ordered a replacement STK-3122-3 but I wanted to ask you experienced people your opinion of what might be happening with Pin 7 and 9 and if this is a failure mode? In your experience, does this show a dead STK?
Thanks for any help.
Cheers!