Pioneer DEQ-9200 backlight fix

My car stereo is built around a Pioneer DEQ-9200. It’s a quite high-end, late 90’s sound processor with some nice features like auto-equalisation, a remote control and a three-group internal crossover. I like it a lot as it’s very seriously laid out, and aside from some pre-programmed EQ curves, it doesn’t try to be more “noob-friendly” than it needs to be.

There’s only one problem with it:


It wasn't like this when it was new.

It’s hard to demonstrate the problem with pictures, as the level of light emitted from the display was so low in comparison to the buttons; it was hard to read even in a completely darkened room.

Upon taking the backside of the front panel off, one is greeted by two ICs, some passive components, two lightbulbs (the next thing to fail) and the solder blobs that supply power to the EL sheet that illuminates the display, as well as the “bendies” that hold the display assembly in place.

Lovely, Pioneer-branded ICs.

That's a quite nice-looking board.

On the other side of the board, there’s an LCD display, some LEDs, an IR receiver (top right corner) and a whole bunch of buttons.


Ooh! White!

Underneath the LCD assembly, the white EL sheet is easily accessed. It’s merely taped onto the white piece of plastic with double-sided tape.


The sun has left its mark in less than a year!

Everybody tell me that I've got womanly hands.

There's not much light emanating from that EL sheet.

I’m going to use an EL sheet that I ordered from Electro-Luminescence Incorporated. They didn’t have anything that’d fit perfectly (22x108mm), but their 18x122mm sheet was the closest I could find anywhere.

Isn't that a nice roll of tape?

The EL sheet can't be soldered, so the connection is pressure-based.

I made the pressure connector by soldering two component leads onto the pads on the PCB, and simply bending them in under the sheet. It works a charm, as the LCD assembly presses it down quite snugly.

That's thermally safe tape from Dealextreme.

It's not beautiful, but it's at least... reasonably usable.

Since the sheet was just a little bit too small, I had to strategically place it to illuminate the most important part of the display. I chose the upper part, which houses the graphic and numerical displays, Auto EQ and posistion indicators. The lower part houses the pre-programmed EQ indicators and functions for the F keys.

The interior of my car is kind of rackety.

It works!

Ia! Cthulhu fhtagn! It works! The above picture was taken in broad daylight, even!



18 thoughts on “Pioneer DEQ-9200 backlight fix

    • Hi Lee, was this the correct panel for yours, I also have dim display on my DEQ9200,
      Thanks Tony.

  1. Hi !
    I’m having DEQ-9200 and the display does not work at all. Before it was very dim and than it went off. I was using it without display and was working good. Few days back my car ECM got shot circuit and now DEQ-9200 is showing only illumination lights and no sound out put.

    I’ve bought the DSP to Muscat Oman now to repair and install in my here. But the problem is to get the spare parts. Now I’m in search of a good technician to fix it.

  2. If display spends a few minutes, it’s also necessary to replace the 3 condensers SMS 10µF of map INVERTERS (Support of the screen). For visualizing well, I can transmit a photograph to you if you want.

  3. hahahahahaah but why you refuse to put the lamp again instead of making the change to ultra bright white LEDs, and eliminate the inverter circuit that lets even the hum on the audio line ?? my now has more ‘high voltage and it’ so bright that is very impressive and it shows in full sun perfectly. I used the LEDs of a display iphone 4 s and traspostare light a plexiglass piece of a broken laptop warning. After removing everything in it you see a very rigid transparent sheet and I chose the most ‘order not to create problems under the display. everything works in circa4,75 volts and light and ‘spectacular

  4. Hi, Hope you are well. Came across your site through a google search in regards to my pioneer display which also has EL backlight.
    I brought it from ebay for a retro look :model KEH-P8400R. It all works fine and I think the display is bright (not sure how to compare). But because you did this repair and know a lot about electronics, I was wondering if you know : Do you know why my EL display would making a buzzing sound and also the inverter block too? When the ILL wire is connected on, then the buzz is lower but the screen is less bright.
    I would be grateful if you have any information. Thank You

      • Oh I see. Thanks for the info.
        On that basis, any idea why the buzz quieten down when I connect the ILL wire (which turns on the button backlights)?
        The display will then dim, because its using less power?
        Thx again.

      • Oh ok, understood. Can I ask for further help please.
        My HU was working fine, was doing the final fit and connect everything backup. When I started the system, the right sound was coming through. I saw the RCA was lose and pushed it in. I started car up and now I’m hearing buzzing noise. According to every one the internet Pioneer has issues with the pico fuse that blows quickly with RCA connections. I tried the RCA grounding method as read on forums, but didn’t work. My unit is an older model, and don’t think has a pico fuse but maybe a resistor. Some people have jusp shorted it and works fine. Unfortunately I don’t know which resistor it is or if more than 1 (I only know very basic stuff)
        If I gave you link to the service manual, could you let me know?
        I know I’m asking a lot, but don’t want to waste this unit.
        Thx again

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