Pioneer DDJ-SZ XLR right is distorting

[DjKrish]

Have anyone repaired here a pioneer DDJ-SZ before? I have a unit with the problem of right channel XLR is distorting. But left channel is fine. And best part? The RCA both L and R channels are perfectly fine. I have replaced all possible opamps in that audio out board and all the voltage measures accurately. Sorry i dont have a oscilloscope to measure the input nor the output signal. I have attached the service manual here. Any kind souls can show me a lead? Thank you.

[CapLeaker]

Good news is that you have an identical channel you can compare the broken one to. Bad news is, you don’t have a oscilloscope, as it would make this problem easy. I think you really need to explain better what’s happening.
Does your problem channel have a unbalance, where one side is louder in volume than the other? Is it distorted all the time? At what level does it distort?
Maybe show in the schematic what you have replaced already. See, the XLR jack is balanced audio. So you have 3 pins. GND, a hot side and a cold side. Maybe one is shorted to ground, or the ground is missing, or something is open in one of the sides. Can you post a link to the full service manual?

[DjKrish]

Originally Posted by CapLeaker

Good news is that you have an identical channel you can compare the broken one to. Bad news is, you don’t have a oscilloscope, as it would make this problem easy. I think you really need to explain better what’s happening.
Does your problem channel have a unbalance, where one side is louder in volume than the other? Is it distorted all the time? At what level does it distort?
Maybe show in the schematic what you have replaced already. See, the XLR jack is balanced audio. So you have 3 pins. GND, a hot side and a cold side. Maybe one is shorted to ground, or the ground is missing, or something is open in one of the sides. Can you post a link to the full service manual?

Hi this is the link to the service manual.

https://elektrotanya.com/pioneer_ddj.../download.html


As for your questions, all my levels are at 12pm. When i try the sound on RCA at same levels, sound is good. But when i try the same on XLR, its distorting. I have replaced the 3 OPAMPS and also all the output signal capacitors. Still no luck. If i go to 1PM, it distorts even worse. Only the right channel is distorting while the left channel XLR is fine.

If i lower the fader, the sound is stable, but if i put the fader to maximum, it distorts. The signal LED is below RED so nothing is clipping.

All voltages are accurate -15v and +15. Master L and R signal comes from mainboard to audio out board. On audio out board, the signals are processed and amplified by 3 opamps thats NJM45850. Output to RCA is fine but failing to XLR R. So this problem is not from mainboard as RCA signal are fine. This problem is solely on the audio out board.

[CapLeaker]

Did you try to change the XLR cables around from L to R and R to L, to rule out a cable problem? I still don't know if the broken channel is lower in volume than the working one right before it distorts. With an oscilloscope it would be absolutely no problem to find this. All you can do is to make some resistance checks and see if something is out of line comparing it to the same point of the opposite channel. I wonder if the problem is one of these Protection Zener Diodes on the end like D711 and D712? Swap em around and see if the problem moves to the other channel. Check out the protection fuse P702 what it does.

[DjKrish]

Originally Posted by CapLeaker

Did you try to change the XLR cables around from L to R and R to L, to rule out a cable problem? I still don't know if the broken channel is lower in volume than the working one right before it distorts. With an oscilloscope it would be absolutely no problem to find this. All you can do is to make some resistance checks and see if something is out of line comparing it to the same point of the opposite channel. I wonder if the problem is one of these Protection Zener Diodes on the end like D711 and D712? Swap em around and see if the problem moves to the other channel. Check out the protection fuse P702 what it does.

Yes i swapped various cables, all same. Left is good, right is distorting if put full fader volume. The ports are fine with multi meter check. Checked the zener diodes on diode mode, both are perfectly fine and identical on L and R. The protection fuse is for overload protection. Both are working fine and tested fine.

[CapLeaker]

Noticed right away discolouration on C767 and C768. Swap them out with those from the left channel and see if the problem transfers.

[DjKrish]

Originally Posted by CapLeaker

Noticed right away discolouration on C767 and C768. Swap them out with those from the left channel and see if the problem transfers.

Haha thats not discoloration. Certain caps of those comes in white color and certain comes in yellow color. I already replaced, swapped, no changes. BTW, they read fine as well with a capacitance meter.

[DjKrish]

I'm just curious. These master L and R signals coming from a DAC chip on the main board. Could it be the problem in that?

Its a WM8740SEDS.

[CapLeaker]

Well, I think you are going to need that oscilloscope. The unbalanced comes from the master hot, so that’s working. That leaves the master cold. Not much else you can do besides compare or get that oscilloscope.

[DjKrish]

Originally Posted by CapLeaker

Well, I think you are going to need that oscilloscope. The unbalanced comes from the master hot, so that’s working. That leaves the master cold. Not much else you can do besides compare or get that oscilloscope.

any other possibilities ?

[CapLeaker]

Btw. These caps I pointed out should be the same than the other side. So not sure why the discolouration, unless they are bad or got changed.
Other possibilities? I think not, be abuse the bad channel is actually working with a little extra feature of distortion. You have to be able to see or hear where the distortion is coming from.
I guess you replaced already IC702? So yeah... need to see or hear whats going into this IC and coming out.

[DjKrish]

Originally Posted by CapLeaker

Btw. These caps I pointed out should be the same than the other side. So not sure why the discolouration, unless they are bad or got changed.
Other possibilities? I think not, be abuse the bad channel is actually working with a little extra feature of distortion. You have to be able to see or hear where the distortion is coming from.
I guess you replaced already IC702? So yeah... need to see or hear whats going into this IC and coming out.

Its not discoloration. These caps comes in 2 colors White and Yellow, probably different suppliers thus the different colors but same value. I took out the caps from a DJM same value. BTW, i tested all those caps using a capacitance meter. All near value and correct. No damage.

Any way to test whats going in and out of that IC via a digital multimeter?

[lotas]

Check the transistor switches (mute), if there is no oscilloscope, then try to transfer the input from the left channel to the right one, this will determine the problem in the output stage or in the dac.

[DjKrish]

Originally Posted by lotas

Check the transistor switches (mute), if there is no oscilloscope, then try to transfer the input from the left channel to the right one, this will determine the problem in the output stage or in the dac.

ok will do that and report back

[CapLeaker]

No, a digital multimeter won’t do much here. All you can do is swapping things from the left channel to the right channel and vise versa.

[TMTGTR]

Not a Tech, can't help much.

If memory serves, I had a similar symptom on a cassette deck with RCA jacks. one channel was distorting intermittently. I retouched the solder points on the jacks' connection to the main board. Problem went away.

Good luck!

[DjKrish]

Originally Posted by CapLeaker

No, a digital multimeter won’t do much here. All you can do is swapping things from the left channel to the right channel and vise versa.

Going to try that soon. Ive swapped almost everything with no luck. Going to pop out the smd transistor and check.

[DjKrish]

Originally Posted by TMTGTR

Not a Tech, can't help much.

If memory serves, I had a similar symptom on a cassette deck with RCA jacks. one channel was distorting intermittently. I retouched the solder points on the jacks' connection to the main board. Problem went away.

Good luck!

Wish it was that simple haha. All jack legs are solid. This is more deeper issue.

[DjKrish]

Ive just replaced the mute switches (transistors) - NO GO, still same

swapped components from left to right - NO GO, still same

I'm lost now, not really know what to do anymore........

[CapLeaker]

I think you are going to need that oscilloscope as I suggested earlier. For this project, you don't need a real fancy one either. Something basic will do just fine. Other than that, you just stab around in the dark and get frustrated on top of it.

You know that the unbalanced output jacks work, but not one of the balanced output. The unbalanced ports work of Master Hot. So there must be something either with the Master Cold going on on the bad balanced port or there is something not equal coming out of the DAC. You need to be able to compare that in order to go any further.