I had this brought in by a friend of mine who seems to have an endless supply of old HiFi, the decks had several problem, the first of which was they didn’t seem to register a tape being present. The first and most obvious place to look for this was the leaf switches at the top of the mechanism, when a tape is inserted they close, thereby telling the deck that a tape has been inserted. I metered across them when closed and found all of them had several hundred ohms across the contacts where they should obviously have a dead short. This was going to be problematic as the switches are sealed and I couldn’t find any replacements, the only thing I could do was file a small opening on each switch to give me access to the contacts, once that was done I was able to get a small sliver of card soaked in switch cleaner between the contacts to clean them up, this had to be done on seven or eight switches, so fairly time consuming.
Problem two was there was no movement of the tape, the mechanism would move into playback position but there was no reel takeup. The decks came apart fairly easily to expose the reel drive mechanism where I found the gear sitting on the reel motor shaft had a split in it, this obviously wasn’t gripping the shaft like it should and had to be replaced. Both decks had the same problem. It looked like the belts had been replaced recently, probably in an attempt to resolve this issue, so I left them in place.
Problem three was isolated to deck B, there was no capstan motor drive, I traced this to a defective drive IC and switching transistor.
So everything was now sorted and both decks were behaving perfectly.
