152xs switching inputs on its own

Hi-Fi Corner
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This issue happened about six months ago, went away, and now it’s back: my preamp would not switch to another input, switching back to TUNER input. It was occupied by a streamer connected via RCA - I switched the streamer to CD input but the preamp would still stubbornly switch to TUNER when I press any input buttons on the unit or the remote. With some persistence, it will switch to the desired input but clearly there is an issue somewhere.

I did make sure that automated input selection is turned off (plus reset the unit to factory settings just in case). The only other used input is a phono preamp connected to AUX, also via RCA.

@NeilS have you per chance had heard of a similar issue reported before and was there a recommended solution? Thank you!

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Have you ruled out any external sources of spurious IR in the area - such as artificial lighting & TV screens etc?

Is there anything connected to the 3.5mm RC5 remote port on the 152?

Does the operation of the front panel Tuner button feel the same as the other buttons i.e. not stuck in?

Regards

Neil.

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Hi @NeilS , appreciate you helping me troubleshoot the issue. Yes I moved all remotes to another room to make sure there is no interference. Here is a short video showing an input jumping back to Tuner (sorry I couldn’t make an .mov attachment). You will also notice how all input buttons blink when one is pressed. Sometimes the issue will go away but eventually the input will switch to Tuner. That button feels like the rest, not stuck. And nothing is connected to the remote port

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First, ensure there are no remotes stuck down the edge of sofa or chair cushions - believe it or not this has been the cause of issues in the past!

Otherwise, if you disconnect all sources from the NAC152xs does it still happen?

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In summer with long twilight period, the orange sun coming in through the window would make my UQ2 do random stuff. A bit of cardboard over the logo where the remote sensor is fixed it until I moved.

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Thanks for the video - it’s certainly unhappy about something! Unfortunately, I don’t have a 152 around to have a play with currently.

I’d start by covering the central logo with something (as mentioned above). Check it is successfully blocking the IR by using the remote.

If it still plays up, it must be an internal fault.

The intermittent nature may make troubleshooting on the bench difficult though.

But we like a challenge :grin:

Regards

Neil.

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Great suggestion about disconnecting al sources - thank you. The input was misfiring this morning just like yesterday. Once it was restarted with all sources unplugged, the issue went away. And it now works fine after another restart with the sources plugged back in. I did restart the unit before, so not sure if it’s the restart that fixed it. Maybe something to do with the two RCA cables?

cc @NeilS

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I wonder whether something connected was looking for a route to earth through the signal connection to the Naim system and messed with the control logic circuits?

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If the streamer is the ND5xs in your profile, is the earth switch on the back in the default position?

Regards

Neil.

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I should have updated the profile - I no longer own ND5xs. I’m now have room only for a small system, and got it replaced with a tiny WiiM Ultra. I mainly listen to vinyl anyway :wink:

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If it happens again, try connecting the earth terminal on the rear of the preamp to mains earth.

Regards

Neil.

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That’s a great idea! I will do that.

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