12-06-2017, 09:14 AM
The first tape recorder I ever worked on was a TK5. I was still at school and it belonged to our Group Scoutmaster.
However, it wasn't in that dingy colour scheme but had the same mixture of greys used in later models, such as the TK20 so I wonder if yours is a particularly early model? Should be interesting to see what the date codes on any original valves - I would expect that to be most of them - and other components reveal.
For anybody who has never touched a Grundig machine there is a hidden danger - the top deck fixing screws. These have a domed head and a curved slot. Using a normal driver on these is virtually guaranteed to cut into the soft brass which, apart from the appearance, is almost certain to leave two upright razor-sharp spikes which are guaranteed to snag on every finger that comes into contact with them!
It looks as if a coin would be the best bet but even this can be a problem as, apart from being fiddly, the coin can sometimes also engage with, and scratch, the edges of the countersunk depressions in the surrounding cover plate.
I should still have kicking around the special tool I made 50 or so years ago to resolve the matter.
It was based on a tip I read somewhere which was to take a suitable sized coin - an old ha'penny in my case - and cut a segment out of it exactly the right size to fit the slot, then cut a slot in a normal screwdriver blade and solder the coin segment into place and Robert is your father's brother.
I'm sure that the tip I read said to find a suitable foreign coin for this - because it was a criminal offence in those days to deface the coinage of the realm (but you won't tell anyone, will you?)
That law was repealed at the time of decimalisation, so you should be safe now! A modern 2p coin is almost identification in diameter but thicker - which probably a snugger fit in the wide slot. I used a normal sixpenny terminal driver with an eighth of an inch wide blade for mine but the extra thickness of the modern coin will probably mean using something chunkier but you can also use a suitably sized washer in place of the coin if you prefer.
A common fault on the TK5 and the later TK20 can be a little puzzling to find. Grundig supplied these machines with a capacitive microphone which needs a polarizing voltage to function - in this case, the HT line! This is fed via a suitable resistor to the input socket with one of those nasty brown Wima capacitors blocking the DC whilst transferring the audio to the input of the amplifier. Those brown Wima caps should be considered as the German secret defence against the dreaded British Hunts!
Finding an HT source on the input of an audio amplifier is not something that many folk would expect to find! Indeed, back in the day, I often wondered if anybody ever considered breakdown of the valveholder material as the source of the fluctuating positive voltage on the grid!
However, it wasn't in that dingy colour scheme but had the same mixture of greys used in later models, such as the TK20 so I wonder if yours is a particularly early model? Should be interesting to see what the date codes on any original valves - I would expect that to be most of them - and other components reveal.
For anybody who has never touched a Grundig machine there is a hidden danger - the top deck fixing screws. These have a domed head and a curved slot. Using a normal driver on these is virtually guaranteed to cut into the soft brass which, apart from the appearance, is almost certain to leave two upright razor-sharp spikes which are guaranteed to snag on every finger that comes into contact with them!
It looks as if a coin would be the best bet but even this can be a problem as, apart from being fiddly, the coin can sometimes also engage with, and scratch, the edges of the countersunk depressions in the surrounding cover plate.
I should still have kicking around the special tool I made 50 or so years ago to resolve the matter.
It was based on a tip I read somewhere which was to take a suitable sized coin - an old ha'penny in my case - and cut a segment out of it exactly the right size to fit the slot, then cut a slot in a normal screwdriver blade and solder the coin segment into place and Robert is your father's brother.
I'm sure that the tip I read said to find a suitable foreign coin for this - because it was a criminal offence in those days to deface the coinage of the realm (but you won't tell anyone, will you?)
That law was repealed at the time of decimalisation, so you should be safe now! A modern 2p coin is almost identification in diameter but thicker - which probably a snugger fit in the wide slot. I used a normal sixpenny terminal driver with an eighth of an inch wide blade for mine but the extra thickness of the modern coin will probably mean using something chunkier but you can also use a suitably sized washer in place of the coin if you prefer.
A common fault on the TK5 and the later TK20 can be a little puzzling to find. Grundig supplied these machines with a capacitive microphone which needs a polarizing voltage to function - in this case, the HT line! This is fed via a suitable resistor to the input socket with one of those nasty brown Wima capacitors blocking the DC whilst transferring the audio to the input of the amplifier. Those brown Wima caps should be considered as the German secret defence against the dreaded British Hunts!
Finding an HT source on the input of an audio amplifier is not something that many folk would expect to find! Indeed, back in the day, I often wondered if anybody ever considered breakdown of the valveholder material as the source of the fluctuating positive voltage on the grid!
