Thanks for sharing this.
Those IC pins surely look like they were eaten away by oxidation. Water-damage ?

It's actually very rare to see these early ICs fail.
The above symptoms are usually those of a bad low-voltage rectifier.

Martin

Hi Martin!

This Beomaster  was very clean and original internally with no evidence of water damage to the rest of the board.

A similar type of failure can occur with small signal plastic packaged transistors. The metal migrates out across the plastic as a plating and shorts the pins. This has been discovered in 70's era vintage Sansui equipment (and other brands)

 I have seen one other instance of the IC failure in a Beomaster 2400, although the problem was not as severe. A bad batch of ICs? Who knows...

I'm not sure of the mechanism behind the failure, whether is caused by humidity or contamination in the encapsulation plastic.

Thanks Cozza, I found the same fault in a BeoMaster 2400-2 which would shut down as soon a the finger was removed from the input selector button. I removed the two ICs 5 & 6, buffed the pins and between with a fine wire brush in a Dremel tool, then cleaned the IC cases with solvent and replaced. The unit now operates correctly.

Hi cozza. I know this is a very old thread but was hoping that I might get a response. My 2400-2 started acting up a couple of years ago. It would lock on P4 after and hour or so of use which slowly went down to a few minutes. I read your thread and changed IC5 and IC 6 after finding the pins were corroded exacly as in your post. After reassembly it now switches to P1 after 3 or so minutes instead of P4. I can see in the schematic that transistors TR1 to TR7 and TR15 to TR22 are also part of the touch panel but I would like to see if it would be possible to narrow things down a bit more. I am also thinking that one of the new IC´s that I installed might be also faulty or that I might have mishandled one during instalation. Namely IC5 seeing that it handles the P1 preset. I have also changed all of the electrolytics. Apart from this problem, it sounds fine and doesn´t seem to have any other fault. Any help would be greatly appreciated.

Check (or replace) the D50 rectifier as the first thing. It's known to cause intermittent problems, often related to source selection.

Martin

Thanks Dillen. I try that first.