Pioneer SX-737 No Sound, No Relay Click, Lights On

[pa_200]

And don't forget the readings pa_200 was asking for on post 275 and 306. I would like to see these too.

@golfnut
The requested DC voltages on post 306 are more important right now. If I would like to see more, I will tell you.

And one more point to be clear.
The foil side print shows always the bottom side of the board and should help to identify the parts position and the traces.

 

[pa_200]

Excellent explanation. So can I take a dmm with a lead on my solder joint and the other lead on a different solder joint that’s on the same trace and confirm that it’s soldered ok?

That’s exactly the same test procedure I asked you in Post #254. Take it as a standard check every time you work on the board, before you continue.

P

Post in thread 'Pioneer SX-737 No Sound, No Relay Click, Lights On'

Feb 2, 2026

The most challenging errors to find, are always the self-produced problems!

Now disconnect the unit from power, we have to examine your new solder joints.
Get your DMM ready and set it to resistance.

The basic setup when measuring resistance. Set the DMM to resistance hold both probes together, check the internal resistance of your probe leads and write it down, so you can subtract the value from the follow-on measurement, if it's greater than 1 Ohm.

You have changed 6 transistors each with 3 legs. That means there are 18 solder pads and 18 traces you should thoroughly check, that they...

• pa_200

 

[mrk229]

1.This is after the my old solder was removed.
2.Leads are trimmed and pushed down.
3.Then flux and soldered with lead solder.
4. No change in relay.

Bravo. Those solder joints look much much better than your earlier ones.

 

[golfnut]

If you have all parts installed, let's test something else.
Please get the DC voltage from all 6 marked points AND pin 6, 8 and 14.
Black probe to chassis and red probe on the markings.

View attachment 3692065

These measurements are before changing the C1 capacitor. I will do that later this morning.
L1 23.5VDC
L2 .5VDC
L3 .5VDC
R1 4.9VDC
R2 5.0VDC
R3 25.1
PIN 6 33.7VDC
PIN 8 .3MV
PIN14 .3MV

 

[pa_200]

These measurements are before changing the C1 capacitor. I will do that later this morning.
L1 23.5VDC
L2 .5VDC
L3 .5VDC
R1 4.9VDC
R2 5.0VDC
R3 25.1
PIN 6 33.7VDC
PIN 8 .3MV
PIN14 .3MV

Interesting!
Leave C1 were it is for now.
Pull only C9, then measure DC Voltage on Pin 1, 2, 3, 17, 18, 19 with C9 pulled and report back
Edit: Use the transistor tester after you pulled C9, and check /report the test values as well.

 

[golfnut]

Interesting!
Leave C1 were it is for now.
Pull only C9, then measure DC Voltage on Pin 1, 2, 3, 17, 18, 19 with C9 pulled and report back
Edit: Use the transistor tester after you pulled C9, and check /report the test values as well.

View attachment 3692656

I am sorry. I didn’t see this and was doing what was asked before. So I changed out the C1 and tried to reflow pins 7-11. Then I turned it on and got a CLICK!!! Yeah!

What do I do now?

 

[pa_200]

Measure DC Voltage on Pin 1, 2, 3, 17, 18, 19 and report back. Tell us if you there is still somethng removed.
Edit: Use the transistor tester after you pulled C1, and check /report the test values of the old C1 as well.

 

[golfnut]

Measure DC Voltage on Pin 1, 2, 3, 17, 18, 19 and report back. Tell us if you there is still somethng removed.

The measurements bounce around but the high points for:
Pins 1, 2, 3 are .5vdc
Pins 17, 18, 19 are .4vdc

They really fluctuate with no steady constant reading.

Nothing has been removed.

 

[fucanay]

I am sorry. I didn’t see this and was doing what was asked before. So I changed out the C1 and tried to reflow pins 7-11. Then I turned it on and got a CLICK!!! Yeah!

What do I do now?

Well, that sure is exciting.

Never mind 1, 2 and 18, 19 for this moment. 3 and 17 are looking much better. That is why your relay clicked over. Can you put the multi meter in mv DC and see if you can get a more precise reading? And can you remind me if you own hook clip or alligator clip attachements for your multi meter or not? Those come in handy with what I want you to do next.

 

[pa_200]

That gives some hope for a cautious “Bingo”, or a light at the end of the tunnel.
Pull only C9, then measure DC Voltage on Pin 1, 2, 3, 17, 18, 19 again with C9 pulled and report back.
What is the range of the fluctuation?

 

[pa_200]

Well, that sure is exciting.

Never mind 1, 2 and 18, 19 for this moment. 3 and 17 are looking much better. That is why your relay clicked over. Can you put the multi meter in mv DC and see if you can get a more precise reading? And can you remind me if you own hook clip or alligator clip attachements for your multi meter or not? Those come in handy with what I want you to do next.

As far as I have seen, he has Autorange . That is not always helpful.

 

[fucanay]

That gives some hope for a cautious “Bingo”, or a light at the end of the tunnel.
Pull only C9, then measure DC Voltage on Pin 1, 2, 3, 17, 18, 19 again with C9 pulled and report back.
What is the range of the fluctuation?

He came out of protections, why are we pulling C9 now? It is certain that the 5VDC he had there before changing C1 and re-flowing those joints changed that voltage. If anything he should be just rechecking what you asked before hand.

 

[golfnut]

Well, that sure is exciting.

Never mind 1, 2 and 18, 19 for this moment. 3 and 17 are looking much better. That is why your relay clicked over. Can you put the multi meter in mv DC and see if you can get a more precise reading? And can you remind me if you own hook clip or alligator clip attachements for your multi meter or not? Those come in handy with what I want you to do next.

I do have clips and I turn the unit off before going to the next pin.

I have another dmm and it has 2000m and a 200m as a setting.

The measurements are still jumping around. Should I give it time to warm up? It seems like I read somewhere that for the dc offset, when adjusting, which I'm not doing right now, but you have to wait a few minutes. Just grasping as I would love to take a video, but I can't post it.

 

[pa_200]

He came out of protections, why are we pulling C9 now? It is certain that the 5VDC he had there before changing C1 and re-flowing those joints changed that voltage. If anything he should be just rechecking what you asked before hand.

C9 should have 25VDC on plus (value of R3) and below 0 vdc on minus if it’s working.
But on #324 he reports position R2 with 5.0VDC which is as well C9 minus.
I just like to see what happens with C9 pulled.
What is the range of the fluctuation?

Nevertheless, I would recommend as a final step, to replace at least C7, 8, 9 and 10, together with C1 and C2.

 

[golfnut]

I have kept the unit one for 13 minutes on Pin 17, It still fluctuates between -200mv to +300mv. It's just random and quickly changes.

 

[fucanay]

The measurements bounce around but the high points for:
Pins 1, 2, 3 are .5vdc
Pins 17, 18, 19 are .4vdc

They really fluctuate with no steady constant reading.

Nothing has been removed.

The fluctuation is pretty normal, but .5vdc is 500mv and we want that to be closer to 0mv to 5mv range.

That Tantalum was cooked, as they get from time to time. This was likely the issue.

I also am not super comfortable with the re-flow on pin 9, it's awfully close to an unrelated trace. The rest look ok enough but I'd rather they not look like little balls of solder. It might take some more heat to get them to really flow. Like I said before, use some flux to help them out.

I do have clips and I turn the unit off before going to the next pin.

I have another dmm and it has 2000m and a 200m as a setting.

The measurements are still jumping around. Should I give it time to warm up? It seems like I read somewhere that for the dc offset, when adjusting, which I'm not doing right now, but you have to wait a few minutes. Just grasping as I would love to take a video, but I can't post it.

Ok, clip your black lead to ground and your red lead to Pin 3 and switch it to 2000m for now, once you get closer to 0V you'll be able to switch to 200m to get a finer adjustment. You'll use VR3 to adjust. Your trimmers aren't great and very old (should be replaced. They are single turn, meaning 1 turn covers the entire range, and will change value very quickly, so VERY SMALL movements on that until you get the number you're looking for.

C9 should have 25VDC on plus (value of R3) and below 0 vdc on minus if it’s working.
But on #324 he reports position R2 with 5.0VDC which is as well C9 minus.
I just like to see what happens with C9 pulled.
What is the range of the fluctuation?

Nevertheless, I would recommend as a final step, to replace at least C7, 8, 9 and 10, together with C1 and C2.

When he changed C1 and re-flowed the pins, it changed Pin 3 ,which is electrically connected to the negative of C9, down to the mv range no longer 5VDC. He needs to adjust the DC offset now. Also confused about the R3 reference which is on the input side.

 

[pa_200]

Recheck that the Function switch is set to AUX
Volume control set fully left minimum
Speaker A selected button pressed

 

[fucanay]

I have kept the unit one for 13 minutes on Pin 17, It still fluctuates between -200mv to +300mv. It's just random and quickly changes.

17 is for the right channel, which isn't what we've been narrowing things down to. Pin 3 is the left channel equivalent of pin 17.

If you want to post videos, use youtube. It's pretty simple to post them and you have the ability to make them unpublished and just send us a link to the video. That's what I did on mine earlier.

 

[golfnut]

17 is for the right channel, which isn't what we've been narrowing things down to. Pin 3 is the left channel equivalent of pin 17.

If you want to post videos, use youtube. It's pretty simple to post them and you have the ability to make them unpublished and just send us a link to the video. That's what I did on mine earlier.

I’ll report back in about 20 mins. Thanks so much. It seems like we are making some headway!

 

[fucanay]

I’ll report back in about 20 mins. Thanks so much. It seems like we are making some headway!

Not just headway, I'd gamble that thing makes sound.

Still, take it slow. No mistakes. Do as pa_200 asked in post 337, that is essential for getting this reading correct.