no change in one channel when adjusting idle current on pioneeer sx-1050

Do you have a DBT?
Watthour is saying the output transistors are not conducting and no current is flowing through them.
With the receiver on the DBT. Volume turned to min/down and no inputs. Clip the black DMM lead to chassis and the red probe to pin 24. Adjust the idle trimmer from full CCW to CW and watch the DMM for DC voltage. Return the trimmer back to min, full CCW.
The range is from millivolts to a few volts.
Then clip to pin 28 and perform the above procedure once again.
Record and report.

You can perform this procedure to the good channel and see for yourself the differences. Easy on the trimmer when going full to full idle. It will open up the outputs. Just do enough trimmer too see the good side working correctly.

The procedure is checking the driver circuit.
 
Do you have a DBT?
Watthour is saying the output transistors are not conducting and no current is flowing through them.
With the receiver on the DBT. Volume turned to min/down and no inputs. Clip the black DMM lead to chassis and the red probe to pin 24. Adjust the idle trimmer from full CCW to CW and watch the DMM for DC voltage. Return the trimmer back to min, full CCW.
The range is from millivolts to a few volts.
Then clip to pin 28 and perform the above procedure once again.
Record and report.

You can perform this procedure to the good channel and see for yourself the differences. Easy on the trimmer when going full to full idle. It will open up the outputs. Just do enough trimmer too see the good side working correctly.

The procedure is checking the driver circuit.
Unfortunately i dont have one.Any thoughts on where i could purchase one?
 
Unfortunately i dont have one.Any thoughts on where i could purchase one?

Build one.
http://audiokarma.org/forums/index.php?threads/dim-bulb-tester-build-and-how-to.808399/

The jest is, the bulb is in series with the units power. If the receiver has a short the bulb covers the load and glows bright (This is Bad). If the receiver has no short or potential to ground the bulb is dim (This is Good).
Others can explain it much better but you need to build one. The circuit diagram in the thread is the key. You can use salvaged components to build your DBT.
You'll need at least a 100 watt bulb for the DBT when using it on your 1050.

By the way. Can you update your profile and list the city you reside?
 
Last edited:
If you have a noted copy of the schematic, you can compare your measured voltages with those marked around Q14, 16, 18, and 20.

I am also a bit confused over the reported voltages. Post # 7 indicated that Power Amp board pins 3 & 18 had the correct -60V supply for the L and R channels, and that the corresponding PNP emitter sense voltages on pins 2 (L channel) and 19 ((R channel) were WAY off:

1= 59.7
2= 40mv
3= -59.4
4= 34mv
5= 0
6= 0
7= -58.7
8= 0
9= 0
10= 63
11= 0
12= 0
13= -58.7
14= -58.7
15= 0
16= 0
17= 0
18= -60
19= 60.8
20= 0

The reported voltage readings from the Protection board in Post # 17 don't quite seem to correspond, showing that pins 7 (L channel) and 5 (R channel) had notable differences:

1) 0
2) -12.6
3) 7.43ac
4) 27mv
5) -37mv
6) 30mv
7) 37mv
8) -30mv
9) 0mv
10) 0
11) 33mv
12) 62.5v

Before proceeding elsewhere, it might be good to test the emitter resistors for the outputs (½Ω / 5W) for continuity.
 
Do you have a DBT?
Watthour is saying the output transistors are not conducting and no current is flowing through them.
With the receiver on the DBT. Volume turned to min/down and no inputs. Clip the black DMM lead to chassis and the red probe to pin 24. Adjust the idle trimmer from full CCW to CW and watch the DMM for DC voltage. Return the trimmer back to min, full CCW.
The range is from millivolts to a few volts.
Then clip to pin 28 and perform the above procedure once again.
Record and report.

You can perform this procedure to the good channel and see for yourself the differences. Easy on the trimmer when going full to full idle. It will open up the outputs. Just do enough trimmer too see the good side working correctly.

The procedure is checking the driver circuit.
built a dim bulb tester with a 150 watt bulb.Sorry DBT thgrough me off.lol
 
The 150 watt is fine.
Good, your on your way.
You-Tube has lots of info on the operation of the DBT.
It's a current limiter. The receiver won't work properly when plugged in to the DBT but you can get voltages needed for troubleshooting.
I use it when powering up on line voltage after making any changes or repairs to any circuit on the receiver. You never know what was jimmied when your mucking about inside. The vintage sets are fragile and anything can give way without notice, let alone your own mistakes.
 
If you have a noted copy of the schematic, you can compare your measured voltages with those marked around Q14, 16, 18, and 20.

I am also a bit confused over the reported voltages. Post # 7 indicated that Power Amp board pins 3 & 18 had the correct -60V supply for the L and R channels, and that the corresponding PNP emitter sense voltages on pins 2 (L channel) and 19 ((R channel) were WAY off:

1= 59.7
2= 40mv
3= -59.4
4= 34mv
5= 0
6= 0
7= -58.7
8= 0
9= 0
10= 63
11= 0
12= 0
13= -58.7
14= -58.7
15= 0
16= 0
17= 0
18= -60
19= 60.8
20= 0

The reported voltage readings from the Protection board in Post # 17 don't quite seem to correspond, showing that pins 7 (L channel) and 5 (R channel) had notable differences:

1) 0
2) -12.6
3) 7.43ac
4) 27mv
5) -37mv
6) 30mv
7) 37mv
8) -30mv
9) 0mv
10) 0
11) 33mv
12) 62.5v

Before proceeding elsewhere, it might be good to test the emitter resistors for the outputs (½Ω / 5W) for continuity.
Do you have a DBT?
Watthour is saying the output transistors are not conducting and no current is flowing through them.
With the receiver on the DBT. Volume turned to min/down and no inputs. Clip the black DMM lead to chassis and the red probe to pin 24. Adjust the idle trimmer from full CCW to CW and watch the DMM for DC voltage. Return the trimmer back to min, full CCW.
The range is from millivolts to a few volts.
Then clip to pin 28 and perform the above procedure once again.
Record and report.

You can perform this procedure to the good channel and see for yourself the differences. Easy on the trimmer when going full to full idle. It will open up the outputs. Just do enough trimmer too see the good side working correctly.

The procedure is checking the driver circuit.
Do you have a DBT?
Watthour is saying the output transistors are not conducting and no current is flowing through them.
With the receiver on the DBT. Volume turned to min/down and no inputs. Clip the black DMM lead to chassis and the red probe to pin 24. Adjust the idle trimmer from full CCW to CW and watch the DMM for DC voltage. Return the trimmer back to min, full CCW.
The range is from millivolts to a few volts.
Then clip to pin 28 and perform the above procedure once again.
Record and report.

You can perform this procedure to the good channel and see for yourself the differences. Easy on the trimmer when going full to full idle. It will open up the outputs. Just do enough trimmer too see the good side working correctly.

The procedure is checking the driver circuit.
Do you have a DBT?
Watthour is saying the output transistors are not conducting and no current is flowing through them.
With the receiver on the DBT. Volume turned to min/down and no inputs. Clip the black DMM lead to chassis and the red probe to pin 24. Adjust the idle trimmer from full CCW to CW and watch the DMM for DC voltage. Return the trimmer back to min, full CCW.
The range is from millivolts to a few volts.
Then clip to pin 28 and perform the above procedure once again.
Record and report.

You can perform this procedure to the good channel and see for yourself the differences. Easy on the trimmer when going full to full idle. It will open up the outputs. Just do enough trimmer too see the good side working correctly.

The procedure is checking the driver circuit.
Do you have a DBT?
Watthour is saying the output transistors are not conducting and no current is flowing through them.
With the receiver on the DBT. Volume turned to min/down and no inputs. Clip the black DMM lead to chassis and the red probe to pin 24. Adjust the idle trimmer from full CCW to CW and watch the DMM for DC voltage. Return the trimmer back to min, full CCW.
The range is from millivolts to a few volts.
Then clip to pin 28 and perform the above procedure once again.
Record and report.

You can perform this procedure to the good channel and see for yourself the differences. Easy on the trimmer when going full to full idle. It will open up the outputs. Just do enough trimmer too see the good side working correctly.

The procedure is checking the driver circuit.
OK test results in
pin 24) -12.3
pin 28)14.4
No change when turning vr4
pin 33)50mv
pin29) -50mv
dialed in nicely with vr3
 
The 150 watt is fine.
Good, your on your way.
You-Tube has lots of info on the operation of the DBT.
It's a current limiter. The receiver won't work properly when plugged in to the DBT but you can get voltages needed for troubleshooting.
I use it when powering up on line voltage after making any changes or repairs to any circuit on the receiver. You never know what was jimmied when your mucking about inside. The vintage sets are fragile and anything can give way without notice, let alone your own mistakes.
The bulb didnt change when i plugged the reciever in to do testing.Stayed bright
 
If you have a noted copy of the schematic, you can compare your measured voltages with those marked around Q14, 16, 18, and 20.

I am also a bit confused over the reported voltages. Post # 7 indicated that Power Amp board pins 3 & 18 had the correct -60V supply for the L and R channels, and that the corresponding PNP emitter sense voltages on pins 2 (L channel) and 19 ((R channel) were WAY off:

1= 59.7
2= 40mv
3= -59.4
4= 34mv
5= 0
6= 0
7= -58.7
8= 0
9= 0
10= 63
11= 0
12= 0
13= -58.7
14= -58.7
15= 0
16= 0
17= 0
18= -60
19= 60.8
20= 0

The reported voltage readings from the Protection board in Post # 17 don't quite seem to correspond, showing that pins 7 (L channel) and 5 (R channel) had notable differences:

1) 0
2) -12.6
3) 7.43ac
4) 27mv
5) -37mv
6) 30mv
7) 37mv
8) -30mv
9) 0mv
10) 0
11) 33mv
12) 62.5v

Before proceeding elsewhere, it might be good to test the emitter resistors for the outputs (½Ω / 5W) for continuity.
all of the emitter resistors .5 ohms
 
Did you test the DBT before you used it on the 1050?
A bright bulb means there's a short in the receiver.
An incandescent bulb is what you should use in the DBT.
 
Did you test the DBT before you used it on the 1050?
A bright bulb means there's a short in the receiver.
An incandescent bulb is what you should use in the DBT.
My mistake i had the bulb wired parralell instead of series.bulb came on bright and then dim almost out,but did not blow
 
If you have a noted copy of the schematic, you can compare your measured voltages with those marked around Q14, 16, 18, and 20.

I am also a bit confused over the reported voltages. Post # 7 indicated that Power Amp board pins 3 & 18 had the correct -60V supply for the L and R channels, and that the corresponding PNP emitter sense voltages on pins 2 (L channel) and 19 ((R channel) were WAY off:

1= 59.7
2= 40mv
3= -59.4
4= 34mv
5= 0
6= 0
7= -58.7
8= 0
9= 0
10= 63
11= 0
12= 0
13= -58.7
14= -58.7
15= 0
16= 0
17= 0
18= -60
19= 60.8
20= 0

The reported voltage readings from the Protection board in Post # 17 don't quite seem to correspond, showing that pins 7 (L channel) and 5 (R channel) had notable differences:

1) 0
2) -12.6
3) 7.43ac
4) 27mv
5) -37mv
6) 30mv
7) 37mv
8) -30mv
9) 0mv
10) 0
11) 33mv
12) 62.5v

Before proceeding elsewhere, it might be good to test the emitter resistors for the outputs (½Ω / 5W) for continuity.
amp board double checked
1)53.8
2)46mv
3)-53.7
4)43mv
5)0
6)41mv
7)-58.3
8)0
9)0
10)62.3
11)0
12)0
13)-58.4
14)-58.2
15)0
16)0
17)0
18)-54
19)0
20)53.6
 
power supply awr-103
1)20.8
2)-014mv
3)-70.4
4)0
5)13.3
6)13.3
7)-12.5
8)-58.3
9)-29.4
10)-23.9
11)-23.9
12)0
13)25.7
14)25.7
15)31.6
16)62.6
17)62.6
18)5.98
19)5.97
 
Thanks for posting the updated voltages. There is still a difference at Pins 4 & of the protection board which exceeds the bias voltage of the transistor (Q2) and is likely due the the inability to adjust the bias of the amp circuit.

I still think it would be good to test the voltages at Q14, 16, 18, and 20.
 
Thanks for posting the updated voltages. There is still a difference at Pins 4 & of the protection board which exceeds the bias voltage of the transistor (Q2) and is likely due the the inability to adjust the bias of the amp circuit.

I still think it would be good to test the voltages at Q14, 16, 18, and 20.
I definitely will and post my results tomorrow.Alittle burned out tonight.
 
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