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Pioneer SX-1010 output transistors

merlynski said:
Definite power amp problem. Both channels the same?
Start with checking dcv levels, on each channel's AWH-032 PCB:

Left Pin 4, sb +56vdc:
Left Pin 3 & 7, sb -56vdc:
Left Pin 8, sb 54vdc:
Left Pin 11, sb -54vdc:

Right Pin 4, sb +56vdc:
Right Pin 3 & 7, sb -56vdc:
Right Pin 8, sb 54vdc:
Right Pin 11, sb -54vdc:
Click to expand...


Yes, both channels show the same symptom.

Left Pin 4, sb +56vdc: 56.5v
Left Pin 3 & 7, sb -56vdc:-57v (both)
Left Pin 8, sb 54vdc: 55.5v
Left Pin 11, sb -54vdc: -55.5v

Right Pin 4, sb +56vdc:56.5v
Right Pin 3 & 7, sb -56vdc:-57v (both)
Right Pin 8, sb 54vdc: 55.5v
Right Pin 11, sb -54vdc:-55.5v
 
Your using your body as an antenna, collecting the AC around you (Example: florescent lights near by) to inject a 60hz signal, via your finger into the amps input.
Feet on the floor, other hand in the air.
You don't have to ground yourself or disconnect any wires in the receiver. There's little to no voltage on that input pin.
 
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Those PS numbers are fine! You stated in a previous post that it has never worked for you, so a closer look is warranted.
Check pins 5 to the Power-input RCA shield connection and pin 18 for connection to ground on both channels.
Verify transistors in place are proper replacements or are original. Recheck orientation of all transistors, compare original legs orientation to replacement orientation (datasheet). If one was installed wrong on one channel, it was probably installed wrong on the other channel as well, giving a 'common' fault.
Recheck orientation of all electrolytic caps that were (may have been) replaced, same logic.
Measure dcv on the collector of Q3, sb about +0.55vdc, on both channels.
Check the correct output transistor are in the correct places, i.e. PNP and NPN are not swapped on the heatsinks.
 
merlynski said:
Those PS numbers are fine! You stated in a previous post that it has never worked for you, so a closer look is warranted.
Check pins 5 to the Power-input RCA shield connection and pin 18 for connection to ground on both channels.
Verify transistors in place are proper replacements or are original. Recheck orientation of all transistors, compare original legs orientation to replacement orientation (datasheet). If one was installed wrong on one channel, it was probably installed wrong on the other channel as well, giving a 'common' fault.
Recheck orientation of all electrolytic caps that were (may have been) replaced, same logic.
Measure dcv on the collector of Q3, sb about +0.55vdc, on both channels.
Check the correct output transistor are in the correct places, i.e. PNP and NPN are not swapped on the heatsinks.
Click to expand...

Check pins 5 to the Power-input RCA shield connection and pin 18 for connection to ground on both channels. - checked, all 4 measure 0.4ohms to chassis
Verify transistors in place are proper replacements or are original. Recheck orientation of all transistors, compare original legs orientation to replacement orientation (datasheet). If one was installed wrong on one channel, it was probably installed wrong on the other channel as well, giving a 'common' fault.
Recheck orientation of all electrolytic caps that were (may have been) replaced, same logic.
Measure dcv on the collector of Q3, sb about +0.55vdc, on both channels.
Check the correct output transistor are in the correct places, i.e. PNP and NPN are not swapped on the heatsinks.

This is a snap of the datasheet of MJ21194G/MJ21193G
upload_2021-1-2_19-19-57.png

This second drawing is my conclusion based on that... Please help me to confirm:
Think that you are facing the markings of the transistor and that the circles in blue are not actually visible.
upload_2021-1-2_19-32-55.png

I keep getting amazed by how ambiguous these datasheets can be, but I humble myself, since the industry has been there for ages and those are made by people much smarter than I am.
Even though is not written anywhere here I think the transistor case is the collector, so that is defined (#3).

If my assumption is correct the transistors are reversed. Emitter and Collector are swapped in the original setting and I was fooled by the markings on the socket saying that the emitter would be on the left side.

Please let me know what you think.

M
 
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On a TO-3 package the case (can) is always* the collector. The screws that hold it to the socket make the electrical connection for the collector to the rest of the circuit (socket). They also provide the pressure to hold the mounting surface against the heatsink.
The writing is on the top of the can, away from the heatsink. Do not expect the dome/cover of the case to be part of the electrical circuit, though it may be connected.
The emitter and base are always the same pins, looking at the side of the transistor they come from (bottom). See attached file drawing.
*EDIT: In my experience.
 

Attachments

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merlynski said:
On a TO-3 package the case (can) is always the collector. The screws that hold it to the socket make the electrical connection for the collector to the rest of the circuit (socket). They also provide the pressure to hold the mounting surface against the heatsink.
The writing is on the top of the can, away from the heatsink. Do not expect the dome/cover of the case to be part of the electrical circuit, though it may be connected.
The emitter and base are always the same pins, looking at the side of the transistor they come from (bottom). See attached file drawing.
Click to expand...

Merlynski, I get that. Lets forget about my wining on the collector.
What is ambiguous to me is very simple...
If I am looking the transistor and reading its letters written on the dome, in the same way I would look at them after they are installed, is the emitter on the right pin or on the left pin?
(I know I cannot see the pins themselves because I am facing the dome)

If the MJ21193/4 follows the standard you posted then the wiring is aligned with the socket:
IMG_20210102_211345.jpg


However, ON datasheet for MJ21193/4 also provisions a "STYLE 2", when the emitter and base are reversed:
upload_2021-1-2_21-23-53.png

That got me concerned for a while.

M
 
mgrisoli said:
Check pins 5 to the Power-input RCA shield connection and pin 18 for connection to ground on both channels.
Verify transistors in place are proper replacements or are original. Recheck orientation of all transistors, compare original legs orientation to replacement orientation (datasheet). If one was installed wrong on one channel, it was probably installed wrong on the other channel as well, giving a 'common' fault.
Recheck orientation of all electrolytic caps that were (may have been) replaced, same logic.
Measure dcv on the collector of Q3, sb about +0.55vdc, on both channels.
Check the correct output transistor are in the correct places, i.e. PNP and NPN are not swapped on the heatsinks.
Click to expand...

Check pins 5 to the Power-input RCA shield connection and pin 18 for connection to ground on both channels. - checked, all 4 measure 0.4ohms to chassis
Verify transistors in place are proper replacements or are original. Recheck orientation of all transistors, compare original legs orientation to replacement orientation (datasheet). If one was installed wrong on one channel, it was probably installed wrong on the other channel as well, giving a 'common' fault. - checked, all transistors match the diagram
Recheck orientation of all electrolytic caps that were (may have been) replaced, same logic. - all checked, +replaced diodes
Measure dcv on the collector of Q3, sb about +0.55vdc, on both channels. - 0.6v on both channels
Check the correct output transistor are in the correct places, i.e. PNP and NPN are not swapped on the heatsinks - checked - I believe replaced output transistors are STYLE 1, what makes the orientation identical to the originals, wires were never disconnected but still checked.

I have not replaced Q9 and Q10, I will place an order for the insulators and replace them, so I can eliminate that possibility.
 
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mgrisoli said:
Merlynski, I get that. Lets forget about my wining on the collector.
What is ambiguous to me is very simple...
If I am looking the transistor and reading its letters written on the dome, in the same way I would look at them after they are installed, is the emitter on the right pin or on the left pin?
(I know I cannot see the pins themselves because I am facing the dome)

If the MJ21193/4 follows the standard you posted then the wiring is aligned with the socket:
View attachment 2085406


However, ON datasheet for MJ21193/4 also provisions a "STYLE 2", when the emitter and base are reversed:
View attachment 2085422

That got me concerned for a while.

M
Click to expand...
That drawing is a Mechanical Drawing for the TO-204 (TO-3) package, it is not a datasheet for a specific transistor, even if it is included with a Datasheet.
Don't let that confuse you, look at the datasheet for the specific transistor you are working with, not the general case Mechanical drawing.
If nothing else, if this is a PNP transistor, clip the negative lead from your meter on the base pin, using the diode range, you will get about 0.6v drop to the emitter and collector, for an NPN the leads are reversed. If you have one of those little transistor testers it will sort them out for you.
FWIW, I do not recall ever seeing a Style 2 transistor.
Page 6 on the attached Datasheet indicates pin designations clearly.
 

Attachments

merlynski said:
That drawing is a Mechanical Drawing for the TO-204 (TO-3) package, it is not a datasheet for a specific transistor, even if it is included with a Datasheet.
Don't let that confuse you, look at the datasheet for the specific transistor you are working with, not the general case Mechanical drawing.
If nothing else, if this is a PNP transistor, clip the negative lead from your meter on the base pin, using the diode range, you will get about 0.6v drop to the emitter and collector, for an NPN the leads are reversed. If you have one of those little transistor testers it will sort them out for you.
FWIW, I do not recall ever seeing a Style 2 transistor.
Page 6 on the attached Datasheet indicates pin designations clearly.
Click to expand...

Thanks man!
I believe that is good and bad news... good news is that the transistors are correctly wired, bad news is that the problem is still there.
I have ran all tests and verifications you suggested, results are here:
mgrisoli said:
Check pins 5 to the Power-input RCA shield connection and pin 18 for connection to ground on both channels. - checked, all 4 measure 0.4ohms to chassis
Verify transistors in place are proper replacements or are original. Recheck orientation of all transistors, compare original legs orientation to replacement orientation (datasheet). If one was installed wrong on one channel, it was probably installed wrong on the other channel as well, giving a 'common' fault. - checked, all transistors match the diagram
Recheck orientation of all electrolytic caps that were (may have been) replaced, same logic. - all checked, +replaced diodes
Measure dcv on the collector of Q3, sb about +0.55vdc, on both channels. - 0.6v on both channels
Check the correct output transistor are in the correct places, i.e. PNP and NPN are not swapped on the heatsinks - checked - I believe replaced output transistors are STYLE 1, what makes the orientation identical to the originals, wires were never disconnected but still checked.
Click to expand...
 
The good news is that we are narrowing down the possible failure items, the 'bad' news is we have not found the problem's cause yet.
Gotta keep diggin'
Pull the Pre-out Power-in jumpers. Power on.
Left channel power amp PCB:
Measure dcv on the collector of Q4, sb +1.8vdc:
Measure dcv on the collector of Q5, sb -1.8vdc:
Measure dcv on the emitter of Q8, sb +0.6vdc:
Measure dcv on the emitter of Q10, sb -0.6vdc:
Repeat for right channel PCB:
Measure dcv on the collector of Q4, sb +1.8vdc:
Measure dcv on the collector of Q5, sb -1.8vdc:
Measure dcv on the emitter of Q8, sb +0.6vdc:
Measure dcv on the emitter of Q10, sb -0.6vdc:

EDIT: correct Q4 to Q10
 
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merlynski said:
The good news is that we are narrowing down the possible failure items, the 'bad' news is we have not found the problem's cause yet.
Gotta keep diggin'
Pull the Pre-out Power-in jumpers. Power on.
Left channel power amp PCB:
Measure dcv on the collector of Q4, sb +1.8vdc:
Measure dcv on the collector of Q5, sb -1.8vdc:
Measure dcv on the emitter of Q8, sb +0.6vdc:
Measure dcv on the emitter of Q4, sb -0.6vdc:
Repeat for right channel PCB:
Measure dcv on the collector of Q4, sb +1.8vdc:
Measure dcv on the collector of Q5, sb -1.8vdc:
Measure dcv on the emitter of Q8, sb +0.6vdc:
Measure dcv on the emitter of Q4, sb -0.6vdc:
Click to expand...

Pull the Pre-out Power-in jumpers. Power on.
Left channel power amp PCB:
Measure dcv on the collector of Q4, sb +1.8vdc: +4.5V
Measure dcv on the collector of Q5, sb -1.8vdc: +1.6V
Measure dcv on the emitter of Q8, sb +0.6vdc: +1.2V
Measure dcv on the emitter of Q4, sb -0.6vdc:+56V
Repeat for right channel PCB:
Measure dcv on the collector of Q4, sb +1.8vdc: +4.4V
Measure dcv on the collector of Q5, sb -1.8vdc: +1.5V
Measure dcv on the emitter of Q8, sb +0.6vdc: +1.2V
Measure dcv on the emitter of Q4, sb -0.6vdc: +56V
 
Voltages at the emitter of Q10 should be -0.6vdc, not +1.8vdc. Emitter of Q8 Q9 sb +0.6vdc.
Measure dcv on the base of:
Left:
Q5:
Q6:
Right:
Q5:
Q6:
All sb -52.8vdc.

DCV drop across:
Left:
R15:
R16:
Right:
R15:
R16:
Sb about 0.1vdc, and equal to each other.
 
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merlynski said:
Voltages at the emitter of Q10 should be -0.6vdc, not +1.8vdc. Emitter of Q8 sb +0.6vdc.
Measure dcv on the base of:
Left:
Q5:
Q6:
Right:
Q5:
Q6:
All sb -52.8vdc.

DCV drop across:
Left:
R15:
R16:
Right:
R15:
R16:
Sb about 0.1vdc, and equal to each other.
Click to expand...

Voltages at the emitter of Q10 should be -0.6vdc, not +1.8vdc. Emitter of Q8 sb +0.6vdc.
Measure dcv on the base of:
Left:
Q5:-53.8v
Q6:-53.5v
Right:
Q5:-53.7v
Q6:-53.5v
All sb -52.8vdc.

DCV drop across:
Left:
R15: 0.25v
R16: 0.001v
Right:
R15:0.25v
R16:0.001v
Sb about 0.1vdc, and equal to each other.
 
Measure dcv on pins 19, 20, again, on the lowest scale of your meter. I don't see how it can be 0v (from previous post) with the readings we are getting in the circuit.
 
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