Thanks, I will try that.

Is the IR decoding on these boards proprietary to B&O or is the IR decoding something common? Can another IR receiver (that uses +5VDC for power) be used as a replacement?

The receiver does not do any decoding of the data per se. It demodulates the signal removing the 455kHz carrier and sends the received data out the output pin, just like the integrated receiver packages do. The IR is also filtered and processed by an automatic gain system before demodulation.

Another receiver chip could be substituted, however the discrete design used by B&O used has very high sensitivity and you will find a TSOP style receiver is very directional if used as a replacement. This means you'll have to aim the remote at the beocenter more.

If you persevere you should be able to fix the receiver. The IC is used in other B&O equipment, so if you have a scrap beolink 5000 or a beaten up link eye (ML) lying around there is a spare in that. It is very unlikely to be the IC at fault, but not impossible. The filter circuitry around the IC is fairly high impedance and would be impaired by leaked electrolyte.

In the past I've found beolink 5000s with poor or no IR receive have had leaky caps around the U2506B receiver, and cleaning the board and replacing the caps fixed the problem, same with the beolink 7000.

The decoded data pulses are pretty short, so make sure you have your scope set to an appropriate timebase when fault finding.

Definitely try a replacement photodiode if recap and cleaning does not fix the problem, however make sure that it is a close or identical replacement. The capacitance of the photo diode affect the tuning of the IR front end filtering.

The BC9300 service manual says it is a B&O part (8330145) - IR Detector 455kHz.  That same part is used in the Beosound MK-III where it is described as an IR Detector, 880nm, 455kHz. The back of the device says TEK BPW82 which appears to be a Vishay photodiode. Mouser has it in stock so I will pick one up before the weekend.

I picked up my replacement photo diode (Vishay BPW82, 60V, 215mW, 650nm) today and I am happy to report that did the trick.  My Beocenter 9300 remote control functionality works.  Thanks for the help in debugging that.

The next step for this project is cosmetic.  The unit came with detached glass panels that I had to reinstall into the plastic trim.  When I first re-installed it I checked the glass borders and didn't see any light pass through.  However, after I glued the pieces in (Aleene's Tacky Glue), various places along the glass border looked like they had bubbles. I was able to easily remove the panels from the trim and get rid of the glue. The glass is missing some black paint from around the edges in a lot of places now.  I have two ideas to repaint it black.  One is to mask off the areas that need light to go through and spray paint the back with a flat black.  The other is to paint the back with a brush using 1Shot Sign Painters' Lettering Enamel (199-L Lettering Black). I guess the best thing to do is take some blank piece of glass and test how well each paint works after painting, drying and test gluing a piece of plastic to it.

-sonavor

My success was short lived.  After I re-installed the IR board into its normal position it stopped working. I removed it again, took off the metal shield box and it started working again.  But only for about a minute. I was able to operate the radio and volume control, then it went dead again.  I am afraid that there are other components (SMD components) that might also be bad.  So I am back without remote control capability on this Beocenter. I have to decide if I want to take on trying to replace the IC and/or transistors.  I will probably wait for a spare to come up for sale. 

-sonavor

Update on this Beocenter 9300. 

After repairing the DC power for the processor on a friend's Beocenter 9500 I started looking at my Beocenter 9300 again. With the 9300 cover open yesterday, the remote control functionality started working again. It continues to work today. So I am thinking this problem must be a wiring or connector problem.  An odd problem for sure these apparent connectivity issues.

I think I am over the hump with the Beocenter remote control problem.  I never had a problem with the remote control functionality while it started working with the BC9300 cover open. I left it like that for a couple of days and tried the remote several times during that period.  It always worked. When I closed the Beocenter up, the remote stopped so it had to be with the connecting cable. I thought about building a new one with new connectors but I decided to remove and resolder the connector on the P2 IR Board.  That did the trick.  I have the Beocenter all put back together and the remote is working properly.  How many times does a problem end up being caused by a bad connection or a wiring problem?

This unit is in getting in pretty good shape. The radio and CD work good.  The auto-reverse cassette deck works okay but I think it needs some maintenance before I can declare it fully functional.