I have a question about refurbishing the glass panels on the Beocenter 9300. There are a few places where the black coating on the back of the panel (where the old glue/tape was) has rubbed off. It is noticeable when the glass is mounting in the trim so I would like to fix that. My local art supply store suggested I clean the back of the glass and paint it with 1 Shot Sign Painter's Enamel Paint.  It sticks to glass and has excellent coverage. I think it only comes in gloss enamel though. Has anyone successfully fixed these Beocenter panels? I am planning on masking off the display areas so no paint gets on the colored film strips.

sonavor wrote:

With power on the IR board, should I be able see signal activity on P49-2 when I press buttons on the remote control?

I haven't seen the schematics of that board, but I can only presume it contains the entire front end - demodulator combination (where does the signal line go in the other end? Directly to a processor pin?), and you should see clean digital level pulses on the signal line. So it seems that it indeed does not work.

As to your panel question, I have simply used a black felt pen on the scrubbed off areas, and can tell diddly squat of a difference to original paint once the panel is installed. If you have larger damaged areas (not just scratches), it might be worth trying a proper paint.

Here is a scan (of a copy) of the Beocenter 9300 IR Receiver.

Looks like you've already changed C8 on PCB2 but there seems to be another of those dreadful leaky Panasonic SMD caps in the silver box.

That one (C9) is smoothing Vref and could well be the reason for not receiving IR.

I think the Beolink7000 has a similar circuit and that is known for missing 2-way-IR-reception with the 22uF Pana's leaking 🙁

Don't know how to open the box, I suppose it's soldered to the board like usual.

You will smell if the cap has been leaking while desoldering it  - a smell you'll never forget again 😕

Good luck,

   Gunther

EDIT: looking at your pictures the metal cover IS soldered to the PCB...

@ tournedos - according to the SM the chip is a U2506B...

hemenex wrote:

Looks like you've already changed C8 on PCB2 but there seems to be another of those dreadful leaky Panasonic SMD caps in the silver box.

That one (C9) is smoothing Vref and could well be the reason for not receiving IR.

Indeed... a typical 455 kHz B&O IR receiver is actually very close to being an AM radio receiver, both functionally and from circuit design viewpoint. It doesn't need much interference to not work properly.

I opened the shielding box. You are right, there is another electrolytic cap inside. I think I will go ahead and change it but I will have to order a smaller size replacement than the standard one I used to replace the cap outside the shield box.

I replaced the other SMD, 22uF capacitor on the IR board but that did not bring the board to life. I double checked the signal again. With power (+5 VDC) applied the board output signal (P49-2) goes up to +5 VDC and stays there. Using the remote control I cannot catch any activity on that line.

You may be "chasing your tail " here somewhat sir?

It's very common for the ir diode to become noisy with age,this will obviously affect the remote control function.

They are readily available,the type No is on the body of the device.I've also used a replacement type available from Maplin Electronics in the UK,or online.

Surface mount electrolytics are also available as direct replacements to fit inside the can etc.

Regards,

Nick

I will try that next then. My replacement components so far were from recommendations of other forum members. The capacitors I replaced were also the easiest for me to try first.

Thanks,
-sonavor

It is a good idea to take a cotton swab dipped in isopropyl alcohol and clean the board thoroughly. Those leaky caps usually leave electrolyte on the board which will be a problem. Don't be afraid to get the board really wet, and focus on the the IC itself, you want to dilute and flush away any residue. I see a couple of the pins look a little green on the U2506 which is typical corrosion from leaked electrolyte.