Old Philips PM6668 counter to 1 GHz --- in trouble

Author	Message
plover Guru Joined: 18/04/2013 Location: Australia Posts: 306	Posted: 01:23pm 04 Jul 2025       Update on counter. After removing the battery unit and scrutinizing the schematic diagram of the battery unit the penny dropped. In the schematic there is an 7805 5V regulator, which is removed when battery unit is installed. I found a 7805 in my stock installed it in 30 second place in socket install a 3 mm csnk 3mm screw, washer and nut. Turn on and measure 5V output but crazy display. Head scratching and accidentally knocking the counter I realised there was an intermittent associated with the pre-scaler board.  Gentle knock on the side of the case now installed seems to start proper operation. this was a pleasant surprise as the pressure to look for modification and to replace display can be put off.