Pioneer sx-535 no sound

MrChips

Joined Oct 2, 2009
26,781
Welcome to AAC!

Firstly, try to find the Service Manual or at the very least a copy of the circuit schematics.

What test equipment do you have?
What is your knowledge and experience in servicing electronic instruments?
 

Thread Starter

Tolman

Joined Jul 17, 2022
6
Welcome to AAC!

Firstly, try to find the Service Manual or at the very least a copy of the circuit schematics.

What test equipment do you have?
What is your knowledge and experience in servicing electronic instruments?
I found the service manual, I only have a multimeter with oscilloscope, I've just started doing some minor things as in cleaning and bulb replacement, I've built a tube amp and preamp kit, reconed some speakers but that's about it
 

MrChips

Joined Oct 2, 2009
26,781
I found the service manual, I only have a multimeter with oscilloscope, I've just started doing some minor things as in cleaning and bulb replacement, I've built a tube amp and preamp kit, reconed some speakers but that's about it
Ok.

First step is to disconnect all speakers.
Turn the volume control down to 0.
Unplug the receiver from AC mains. Open the unit and inspect visually. Look and smell for anything unusual, burn components, charred circuit board, capacitors with bulging tops or leakage.

If you find nothing to report, plug in the receiver and turn on with no speakers attached, volume control still at zero.
Describe any visible activity on the font panel, lights, meter movement, etc.

Use a voltmeter and measure all the supply voltages. You need to follow the Service Manual to locate suitable test points.

Pioneer SX-535 power.jpg

-41V
+30V
+13V
+27V
-27V

Make sure that you indicate + and - signs in your reading.
 

Thread Starter

Tolman

Joined Jul 17, 2022
6
Ok.

First step is to disconnect all speakers.
Turn the volume control down to 0.
Unplug the receiver from AC mains. Open the unit and inspect visually. Look and smell for anything unusual, burn components, charred circuit board, capacitors with bulging tops or leakage.

If you find nothing to report, plug in the receiver and turn on with no speakers attached, volume control still at zero.
Describe and visible activity on the font panel, lights, meter movement, etc.

Use a voltmeter and measure all the supply voltages. You need to follow the Service Manual to locate suitable test points.

View attachment 271698

-41V
+30V
+13V
+27V
-27V

Make sure that you indicate + and - signs in your reading.
On board wr-065 pins 1 thru 17 voltage. Pin 1 -0.005v 2 -26.3v 3 -0.002v 4 -0.002v 5 -0.005v 6 +26.4v 7 -0.27v 8 -0.34v 9 0v 10 -13.7v 11 0v 12 +13.25v 13 +13.25v 14 +13.25v 15 0v 16 +30.2v & 17 +30.2v. It looks like I'm low on pin 10@13.7v.
 

Thread Starter

Tolman

Joined Jul 17, 2022
6
On board wr-065 pins 1 thru 17 voltage. Pin 1 -0.005v 2 -26.3v 3 -0.002v 4 -0.002v 5 -0.005v 6 +26.4v 7 -0.27v 8 -0.34v 9 0v 10 -13.7v 11 0v 12 +13.25v 13 +13.25v 14 +13.25v 15 0v 16 +30.2v & 17 +30.2v. It looks like I'm low on pin 10@13.7v.
I have cleaned and inspected the unit checked all fuses and fm tuner signal and all looks good
 

MrChips

Joined Oct 2, 2009
26,781
On board wr-065 pins 1 thru 17 voltage. Pin 1 -0.005v 2 -26.3v 3 -0.002v 4 -0.002v 5 -0.005v 6 +26.4v 7 -0.27v 8 -0.34v 9 0v 10 -13.7v 11 0v 12 +13.25v 13 +13.25v 14 +13.25v 15 0v 16 +30.2v & 17 +30.2v. It looks like I'm low on pin 10@13.7v.
Thanks for that.
You have found a voltage reading that is not to spec. It should be -41V.

At this point we will take a stab in the dark.
Here is the circuit schematic of the POWER AMP.
Pioneer SX-625 power pin-10.jpg

This capacitor is labeled 220μF/50V.
Locate this capacitor and replace it. The voltage must be 50V or higher (63V would be preferred).
Try to match the 220μF or higher. The value is not critical. Even 470μF should work.
Most importantly, make sure that the orientation of the leads is correct. The positive lead goes to GND.
(Electrolytic capacitors usually have a -ve sign on the negative lead.)

1658158031861.png
1658158608743.png

Here we are hoping that the capacitor is showing excessive leakage which will pull the voltage down at pin-12 on the POWER AMP board (pin-10 on the POWER SUPPLY board).
 

Thread Starter

Tolman

Joined Jul 17, 2022
6
Thanks for that.
You have found a voltage reading that is not to spec. It should be -41V.

At this point we will take a stab in the dark.
Here is the circuit schematic of the POWER AMP.
View attachment 271721

This capacitor is labeled 220μF/50V.
Locate this capacitor and replace it. The voltage must be 50V or higher (63V would be preferred).
Try to match the 220μF or higher. The value is not critical. Even 470μF should work.
Most importantly, make sure that the orientation of the leads is correct. The positive lead goes to GND.
(Electrolytic capacitors usually have a -ve sign on the negative lead.)

View attachment 271723
View attachment 271725

Here we are hoping that the capacitor is showing excessive leakage which will pull the voltage down at pin-12 on the POWER AMP board (pin-10 on the POWER SUPPLY board).
Thanks I have ordered it and the 4 transistors on the heat sink 2sa489 and 2sc789, they had different readings from one to the other like one on the other channel. The solder connections on one looked like a cold solder joint so I figured it couldn't hurt. Thanks for the help. I'm wanting to take a course online at home, do you have anyone you would recommend? Thanks again Steve.
 

MrChips

Joined Oct 2, 2009
26,781
Thanks I have ordered it and the 4 transistors on the heat sink 2sa489 and 2sc789, they had different readings from one to the other like one on the other channel. The solder connections on one looked like a cold solder joint so I figured it couldn't hurt. Thanks for the help. I'm wanting to take a course online at home, do you have anyone you would recommend? Thanks again Steve.
Have you looked at the Education tab in the menu bar at the top of this forum page?
 

Thread Starter

Tolman

Joined Jul 17, 2022
6
Have you looked at the Education tab in the menu bar at the top of this forum page?
OK I'm back ,I replaced 4 ea. C1318 transistors, 2 ea. 2sa489 & 2 ea. 2sc789 transistors and the 220uf 50v cap on board AWH-035. I have low volume with a lot of static on tuner and phono. I'm going to replace the other capacitors, what do I need to use at C1 & C2 it has Sanyo 1/25 on it and M106 on it? Also the diodes at D5 & D6 that has W6A in the parts listing. The other capacitors and diodes I've got. Any help would be greatly appreciated Tolman.
 

MrChips

Joined Oct 2, 2009
26,781
Replacing capacitors at random is a stab in the dark. Sometimes it works. Sometimes it doesn't.
I prefer to take a more informed approach.

So you have two things to go by.

1) You have low volume.
2) You have a lot of static on tuner an photo.

You need two pieces of test equipment that can help diagnose the problem:
1) a source of sound such as an MP3 player,
2) a audio amplifier such as a PC powered speaker.
 
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