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DJM-900NXS2 - No Phono Signal

I've noticed an odd issue on my DJM-900NXS2:

I have no L phono signal on Ch 3 (R is fine), and no R phono signal on Ch 4 (L is fine). Line inputs on both channels are fully-functioning, and all inputs on Ch 1 and Ch 2 are both working as they should.

What would cause this, and what is an appropriate fix?

 

CHAD DARBY Répondu

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HI,

I had a quick look at the schematic of the 900NXS2. There are no shared parts between channel 3L and 4R, at least from the schematic / parts, it should be "all or nothing". So e.g. CH3/Ch4 each one has its own RIAA EQ circuit, where some parts are shared between L and R channel, but not between the different inputs 3 and 4. Also on the PCB there is nothing shared for 3L / 4R obviously.

However, if all other possible problems like cables and plugs have been checked, it looks like this isn't something which can be easily fixed. If you are not very(!) experienced in electronics and have the related test equipment, you have to send this mixer to repair, unfortunately.

Most probably (but no guarantee!) you would have to repair/replace the AINB ASSY (DWX3713).

Regards
Markus

Markus Marquardt 0 votes
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Thanks Marcus.

Yes- cables tested. I actually have never used the phono inputs on those channels until the other day. Who knows how long they've been non-functional.

Yoooouch. That's definitely bigger fix than I expected. I was hoping I had done something in the menu settings. It seems odd that one side works on each channel.

CHAD DARBY 0 votes
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So from the circuit, it is working like this (simplified):

Depending if you have selected LINE or PHONO for an input channel, either the L/R LINE signals or the L/R PHONO signals (after RIAA EQ) are fed to the ADC of this input channel.

The switching between LINE and PHONO is done using a single relay which switches both - the L and R signals.

As your LINE inputs are working properly, it means the ADC is OK, but something between the phono input jack and the relay is not OK. And it is weird that not only a single channel is affected, but half of channel 3 and half of channel 4.

However, you could try to do a factory reset of your mixer, just to be sure it isn't a software issue somehow. The procedure is described in the user manual at page 18.

 

 

Markus Marquardt 0 votes
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Markus- 

Ok, now things are getting really interesting. I just did the factory reset...and now both L/R of PHONO on channel 4 are functional. Now, only the L PHONO on Channel 3 is malfunctioning. I do see a minor amount of signal from the actual contact of plugging in the cable, but very little compared to the functioning channels.

CHAD DARBY 0 votes
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It's hard to believe how the factory reset could have helped :-)

Maybe it is indeed a problem with the physical contact in the RCA jack and by multiple plugging/unplugging during your testing it got resolved?

What you can try:

Plug/unplug your RCA cable on the non-working channel a few times and see if it improves.

Switch between phono/line on the non-working channel a few times, let's say 20 times, and see if it improves. That could help if there is a problem with the relay contacts.

Markus Marquardt 0 votes
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