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Pioneer Sx-1010: Newbie audiophile needs guidance

I have installed the resistors you recommended. the 1k 1 watt ones.


markthefixer said:
First, before power is turned on, we set the positions of the VR pots on each board.

HOw is this accomplished now that they are installed UHG. :sigh:

and have been turned every which way from how they arrived from Mouser? I am trying to spin the 2k ohm one and it seems to spin forever in every direction no matter how long I sit there turning it. Is there supposed to be a hard stop? I know it is a 20 turn or so, but both pots behave the same.

Both VRs are the ones I ordered from the parts list.

This minimum setting , results about 0.4 to 0.6 volts positive (to chassis ground) on pin 10
and -0.4 to -0.6 volts negative (to chassis ground) on pin 13 IF THINGS ARE BEHAVING THEMSELVES.
These voltages will eventually go to the output transistors and tell the output transistors what to do.
IF things are not behaving themselves, the voltages can be far far from the 0.6 volts or so. like 2 volts or 30 volts... (the 10 ohm resistors will pop)


This is as far as I got. ON the board on the right side I get low numbers between -.7 and .7.

On the board on the left I get WILD numbers that vary up and down between - and + number as high as 15 and low as -4.

I tried this a bunch of times to be sure my connections between the added resistors and the boards were good.

What does this mean?



So the process is to chassis ground the black dmm lead, turn on the power and read the voltages found on pins 10, 13 and the resistor's common pin 19 with the red dmm lead.

IF any voltage is GREATER than one volt either positive or negative, shut it down

This is where I stopped today. Left board varies greatly and neither pot seems to change the readings. RIght board seems like it is behaving.

ADDITIONAL NOTES:

Right board is a replacement from Zebulon. it is a A revision board with the extra Capasitor
LEft board is the original board and is a D revision.

Board boards have the same transistors and caps, plus A has the extra Cap.

The BIG .5 ohm resistors are all testing in spec.

NO other resistors or diodes have been touched.
Click to expand...
 
Ok, so I figured that I could unscrew the board and sneak the ends of the probe to touch the solder points on the backside of the board. Across the two middle VRs and the ones On the sides I was able to get to 0.00ohms

This did not seem to make any difference on the LEFT board. It only improved the RIGHT board and I am even closer to between 0.00 and -0.2 (sometimes shooting up a little as high as -.5)

So it seems something is wrong with the Left board?

Something to note: The relay is still clicking on and off at random intervals. At one point I heard it click ON and I happened to be retesting the LEFT board. At this point the 10 and 13 pins dropped to VERY NEAR SPEC!!! Then the relay clicked OFF again and the numbers shot up to 40 on both pins. SOMETHING IS INTERMITTENT?

reminder: the relay worked FINE before I started the upgrades. It is still super shiny and looks brand new. No burning inside or outside.

I also tested my 1k ohm 10watt resistors on 10 and 13 and they are still doing fine.
 

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WHAT are the VOLTAGES???? Especially the BAD ones.

HOW can I help when I don't have voltage readings.

IGNORE the protection as a major indicator.

look for a doughnut solder joint on the offending board.
 
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Get some micro-clips!!! Cheap insurance. :nono:
You don't want to go through what I did. :tears:
 
UHG!!!


1af261d875655e0bf82d6d1d48a9a344629ce715e08bb16326f91cdaf76b6e6d.jpg


I took the support stand off the left side board to try and gain access to the back side of the board to look for "donuts".

Here is what happened when I went to test the 10 and 13 again...

1. Turn on unit
2. DBT bright and then fades
3. Switch went 5 4 3 2 1 CLICK
4. Tested the left board and it WORKS pretty much where it should.

WHY? I do not know. THoughts?

Here i a video of the latest test WITHOUT the back support.

https://www.youtube.com/watch?v=dAVjU9B9H6c
 
rowingcoach said:
UHG!!!


1af261d875655e0bf82d6d1d48a9a344629ce715e08bb16326f91cdaf76b6e6d.jpg


I took the support stand off the left side board to try and gain access to the back side of the board to look for "donuts".

Here is what happened when I went to test the 10 and 13 again...

1. Turn on unit
2. DBT bright and then fades
3. Switch went 5 4 3 2 1 CLICK
4. Tested the left board and it WORKS pretty much where it should.

WHY? I do not know. THoughts?

Here i a video of the latest test WITHOUT the back support.

https://www.youtube.com/watch?v=dAVjU9B9H6c
Click to expand...



RC,

Look at the backside of the board for pins that may not have been trimmed. Meaning did you cut the excess length of the transistors or caps off before you installed the backplate on the 032 boards? Also check for loose wires or solder joints. You also need to make sure the bottom pins do NOT touch the chassis of the unit. Blue tape or similar should be used to isolate that area AS WELL AS taping off the output connectors..

JT
 
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I checked the back side of the board for donuts. No donuts. There were a few of my solders that looked like they could have been better so I redid them. I also cleaned some filmy like substance with some alcohol wipes.

Reinstalled the support bracket board.

Turned it up.

5 4 3 2 1 CLICK.

DBT down to a very fait orange glow.

I get the following voltages on 10 and 13

Right board
10 .8
13 -.5
19 0.00

Left Board
10 .9
13 -.7
19 0.00
 
rowingcoach said:
I checked the back side of the board for donuts. No donuts. There were a few of my solders that looked like they could have been better so I redid them. I also cleaned some filmy like substance with some alcohol wipes.

Reinstalled the support bracket board.

Turned it up.

5 4 3 2 1 CLICK.

DBT down to a very fait orange glow.

I get the following voltages on 10 and 13

Right board
10 .8
13 -.5
19 0.00

Left Board
10 .9
13 -.7
19 0.00
Click to expand...



If you would check my thread out you can follow what Mark had me do with the resistors on 10, 13 and common 19. You can adjust the offset trimmer ever so slightly to see if the voltages change. That trimmer is on the far right of the board. If it changes then chances are the board is fixed. I would WAIT for Mark to guide you so if there is something else in his plan doesn't get missed.

Thanks,

JT
 
craxx6969 said:
If you would check my thread out you can follow what Mark had me do with the resistors on 10, 13 and common 19. You can adjust the offset trimmer ever so slightly to see if the voltages change. That trimmer is on the far right of the board. If it changes then chances are the board is fixed. I would WAIT for Mark to guide you so if there is something else in his plan doesn't get missed.

Thanks,

JT
Click to expand...

thanks. now that I am at this point I am starting to understand that other thread of yours, BUT I do want to wait for MTF just in case. It looks like my voltages are CLOSE but he did say between -.6 and 6... mine are outside those numbers. I am sure that I adjusted the trimmer though to ZERO ohms beforehand on both pots.
 
rowingcoach, does your DMM autorange or do you have to select the range - like 200 volts 20 volts, 2 volts.
If you need to switch ranges, go to the 2 volt range and reread and post the pins 10, 13 & 19 voltages referenced to the chassis ground.

Have you tried turning up and down that idle current pot in the center of the board? When it's position is at the minimum (zero ohms) what are the voltages?
With the 1k (1000 ohm) 10 watt resistors, you can safely turn UP the idle current adjust to get to say +1.0v and -1.0v, so try it as well.

Otherwise we will start probing the circuits that control those voltages.

and as a final check at minumum voltage / idle current pot setting, take a voltage measurement ACROSS pins 10 and 13, meaning the red DMM lead goes to pin 10 and the black dmm lead goes to pin 13, then take the one reading on the 2 volt scale. This is called a differential reading, rather than a ground referenced reading.
 
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I can switch it to 2V range. I have 600v, 200v, 20v, 2v, 200mV

These values are what I have when the middle pot is at the value of zero ohms based on when I probed it and set it to zero ohms. I have not adjusted them from there. If this is "minimum" setting then I have it set. Otherwise, I think the pots DO go lower, but then they wont have the zero ohms when power is off anymore? correct?


On the 2V range selected.
Left board
10 0.990
13 -0.807
19 0.094

right
10 0.857
13 -0.611
19 .112


Across 10 and 13 left
200V scale = 01.7
2V scale= 1.817


Across 10 and 13 right
200V scale = 01.4
2V scale= 1.47

This is my last post for the evening. WOnt be back at the unit till tomorrow AM. THanks!
 
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Read the ohms on the pots at full CCW and then at full CW.

I think the circuit is interfering with the power off readings you were taking.
 
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markthefixer said:
Read the ohms on the pots at full CCW and then at full CW.

I think the circuit is interfering with the power off readings you were taking.
Click to expand...

Just to make sure I understand. you want me to....

1. Power off the unit and unplug
2. turn the pots all the way UP and all the way DOWN and get ohm readings of the two settings.

Is this correct?

Once I have those two readings, where do I leave the pots at? Would it be better for me to remove them from the board to test?
 
Right board

VR2
Clockwise 00.2ohms
CC 1.88 ON THE K ohms SCALE (I had to move the dial up to the next ohm range to get a good reading)

VR1
Clockwise 00.2
CC 0.01

Left Board

VR2
Clockwise .1
CC 157.6 ohms

VR1
Clockwise 0.01
CC 0.01
 
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Should have been more specific, sorry.

I meant only the idle current pots, VR2

Redo:

First you need to turn the vr2 pot in the center of the boards to fully CCW
then set to center the VR1 pots on the edge of the boards, counting turns.

Then turn on the unit, adjust each VR1 for 0.000v on it's pin 19 (if it isn't already at 0.000v) to chassis ground.

With the VR2 in the center of each board at fully CCW, read the voltage BETWEEN pin 10 and pin 13 (DMM: red on 10, black on 13). Should be at or below 1.0 volts.

Then turn up the vr2 pot up until the pin 10 to pin 13 voltage reads 1.8 volts.

Finally set the VR2 pots back to fully CCW and record the pin 10 and pin 13 volts to ground (now two readings, black dmm lead to chassis ground).

BTW, the installation of the VR2 pot on the board (and the board's foil patterns) influences whether full ccw or cw is the zero ohms point.

This is almost to the point where if I don't have any sx-1010 amp boards in boxes, I will have to dig an SX-1010 out of the stack and open it up. Those ohms readings SHOULD have worked.
 
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