Beomaster 8000 memory problems

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geearr Posted: Sat, Feb 9 2013 1:46 AM

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Hi

My Beomaster 8000 continues to work well with full functionality but over the last year has started to develop some problems with the system that stores and accesses the preset radio channels and volume.  Last night for example, I stored nine radio channels and the volume and then accessed them with no problem.  I switched the set off late in the evening, left it on standby overnight and this morning, found that almost everything had been wiped.  So now I have to set it all up again.

The fact that the problem is intermittent leads me to believe that PCB9 might have a bad solder joint or a cracked track but where is this likely to be??  I resoldered all of the pins on the memory chip IC6 and the corresponding pins 6,7,8 and 9 on IC4.  I also checked that those four connections which carry the instructions between the two chips were sound and they seem OK.  So where else can the problem be?

I have no idea how this memory chip is controlled.  The six, 5V connections and the ground seem to be OK but the workings of pins 1, 5, 13, 7 and 6 are beyond my understanding.  Is it possible that the chip is getting a faulty signal to reset and if so, what is it resetting to.

If anyone has a good technical understanding how this part of the BM8000 control system is supposed to work, I would like to hear from you.  What could be going wrong and how can we systematically resolve this problem.  I always hate the idea of resoldering the whole board because of the risk of doing more unnecessary damage.  What should I do next.

Thanks

Geoff