Beomaster 8000 Suddenly Cuts Output Stages Power (Continued)

Again my Beomaster 8000 cut out! I opened it up again, and a quick tracking of the pin 16 voltage revealed that IC4 still did not connect properly to the relay driver. It turned out that the via I thought I had fixed yesterday was still intermittent. The bad contact was on the top side of the via, not at the bottom where I resoldered it. The pic shows the three vias for pins 14-16 from the top after removal of the top part of the shield can.

I resoldered the vias from the top side and now the Beomaster seems to run stable. Note that there is a tendency of the solder to be pulled down below when soldering the via from top on a flat laying board, i.e. the solder bump below gets larger, while from the top it appears that the solder 'vanishes'. This means that the soldering should be relatively quick, just long enough that the bump reflows properly.

Beomaster 8000 Suddenly Goes into Standby Mode

The Beomaster 8000 is on the bench again. After about two weeks of happy service in the living room after 'completing' my restoration, out of a sudden it went into standby. Turned it on again...half an hour later: Standby! Not great. Tried it a few more times....Standby! And again!. I swapped it out with Beomaster 8000-2 (it is like with classic cars...one best has two if one is supposed to run at all times...;-), and opened it up. It turned out that the standby pin (#14 on IC4 - the microprocessor responsible for the radio, volume and startup) occasionally disconnected from the power supply causing the Beomaster to go into standby. This becomes evident by a larger-than-0V voltage (~3.5-4V) at pin 7 on P76 on the microprocessor board (#9). I traced the problem to a bad via on the board. Resoldering the via between P76-7 and pin 14 of the processor solved the problem. Here is a picture:

I resoldered all three vias above the microprocessor (to the right of the C97 label) for good measure. This is done best by simply putting a dab of flux paste on each via, and briefly reheating them with the soldering iron (340C). Use the usual precautions against ESD if you do this in a dry-air environment...the microprocessors are hard to find...;-).