Prime 4+ fx2 button not working

Engine DJ Hardware Standalone Controllers
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Hi everyone,

Having already replaced the channel fader on my Denon Prime 4, a friend of mine gave me his Prime 4+ which he just bought in second hand. The FX 2 button on channel 2 doesn’t light up when pressed and doesn’t work either. Before replacing it, I’d like your opinion: is it possible that the LED on it isn’t lighting up because the tact swith is faulty, and that replacing it would make it light up and work again? Or is it possible that the entire mixer unit needs to be replaced?

Also, would a tact switch for the play button for a DJM2000 that I have, which looks exactly like the FX 2 button I saw in a photo of a Prime 4 mixer’s Pcb, should work?

The djm 2000 button is between 4 and 5 mm and both tabs are between 1.4 and 1.5 cm, I don’t know the size of the prime 4 tact Switches..

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These days, switches and LEDs only have one thing in common: their location.

Switching the switch and controlling the LED are two completely separate things.

In this case, however, it sounds like the switch is simply defective – I’ve seen that with several devices, whether Denon or Pioneer.

Sometimes you’re just unlucky.

The components are industry standard, but I don’t know what you have lying around.

You should be very good at soldering and pay close attention to where and how everything was connected, especially with the “delicate” ribbon cables!

My advice: have someone who really knows what they’re doing handle it, or take it to a repair center, where they’ll almost certainly replace the entire board.

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Hi, thanks for answering me, I didn’t mention it but I’m a computer repairman and I’m ok with soldering. I precised that I disassembled my prime 4 to unsold two dead channel faders and sold new ones with success and I intend to do it again because I broke these new ones AL0-09-0057 :sweat_smile: not so robust too I’m looking for stronger ones but I made an other topic for that.

So for you it is possible that if the led doesn’t light up, it can be because the switch is just dead?

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In countless repaired devices, it was always the switch.

Once it was the entire circuit board, but that was easy to spot because it smelled like Bacardi Orange.

Just bridge the switch. Since it’s normally a momentary switch, that works perfectly.

Then you’ll see if the LED lights up, or you can measure whether there’s any voltage at the LED. It should be around 1.2V… if there’s 5V or more, the LED is probably blown, which is generally a very bad sign.

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Thanks, I’m gonna do it and will let you know, but can you tell me about the compatibility of the Djm2000 tact Switch for the prime 4+?

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Be careful with the ribbon cables. Make a mark with a thin marker so you know how it was mounted!

I can’t tell you the exact type of button off the top of my head; I only have about four types in my workshop, which differ in SMD or via mounting, plus two more by size. They’re usually standard components.

My advice: See if you can access the contacts on the back. Turn the device on and try bridging the contacts with a 470-ohm resistor – even at 12V, the current will only be a maximum of about 25mA.

This usually triggers the function, provided nothing else is defective, which I don’t expect “if everything else is working”.

You should normally be able to measure ground on one side of the button and 3.3V or 5V on the other. If these voltages aren’t measurable, the button might be stuck.

… I’ve had that happen before, recognizable by the missing 3.3V or 5V – it might be, but it doesn’t have to be!!! Then you MUST desolder it!

Definitely wear an anti-static wrist strap! Especially when it’s cold outside and the air is very dry, to avoid static buildup.

Oh yeah, and stay away from the power supply… that can get really nasty! There’s easily 300V DC at the capacitors. That’s really, really dangerous! That’ll give you instant diarrhea, and that would be the least of your worries.

Basically, I can only advise you to take it to an electronics repair shop.

PC components are all designed to be touch-safe and, while they might burn out, they’re unlikely to kill you.

It’s a completely different story with an open switching power supply! I can’t tell you much more from a distance.

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Oooow! OK I didn’t think about the power supply to test this component, I heard about testing it with a 3v cell :sweat_smile: it seems to need more knowledge as the fader replacement, in fact have to test it before and after the soldering of the new makes sens when you know the struggle to get there, all the screws,…

I think I’m gonna let my friend drop it to a repair shop after your last message :victory_hand: thank you for your time

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