Latest Acquisition - Grundig TK 14

[DMcMahon]

It arrived a couple of days back and have had a quick cursory inspection.

It is basically a 2 track version of my TK 23s and came with a grubby looking slightly damaged Grundig GDM 18 microphone.

As expected from sales photos, it is pretty grubby looking, I think some of it will clean up. 2 of the 3 drive belts are broken.

Internally it has 30mm glass fuses, not the more typical 20mm.

[8 Tracker]

That's nice. Grundig did an excellent job with this range of machines. Judging by the amount still around, they must have sold like hot cakes. Simple, very reliable and smart-looking. They are my favourite range of machines.

Yours looks like an early example, before the colour scheme was changed to all-white. Even looking at just the one model, there is variety between them. I've not seen that type of motor before, looks like just a single coil instead of the more usual two. Are there any paper caps on the board? I've just had one cause some trouble on a TK19 that I've aquired. Shame about the drive belts but as I said in another post recently, O rings work nicely, just require careful size selection.

I now have an example of each of the models in the range except the TK17, the basic four track model. The TK27 stereo version is considerably more crammed in than the 14, but still quite enjoyable to work on.

Mark.

[DMcMahon]

Yes the motor is smaller/simpler than what I am used to on the TK 23.

No mains cable with the machine, but it is fitted with a mini Bulgin mains connector, so fitted one of my Bulgin cables and powered up (first did a few measurements to make sure that safe to power up).

Powered up OK, motor runs and the EM84 Magic Eye lights up well. RWD & FFD work (not tried with tape yet). The rubber tread on the Supply Reel Table is somewhat cracked. Removed the FWD/RWD idler to check for pot metal disease (as per a separate thread in another section), it is good.

HT voltage is OK, level lower than schematic value (235 vs 255) but not concerned with that currently and HT mains ripple level typical around 6-7V p-p.

Checked that the 3 anode to grid coupling capacitors (C3, C5 & C10) are not leaking/passing DC, they are good. Not sure what type of capacitors they are but not the old waxed paper type that can cause problems.

Next to do, need to find suitable drive belts for the tape counter and the drive from the flywheel to the Take Up spool (not the easiest belt to fit) then will test Play etc.

[DMcMahon]

Found suitable drive belts and fitted. Completely removed the flywheel to make access to the flywheel belt install easier (although entails a bit of a strip down). Took opportunity to grease the bottom of the flywheel shaft and remove corrosion off the capstan shaft. Also clean and re-lubed where required the general area.

Cleaned the heads (not bad) and removed plenty of fluff from tape path.

With tape fitted RWD, FWD, Play & Pause all work well. Playback sounds good, recording to do next.

Tape counter not working as gearing too stiff, have removed for cleaning and a touch of suitable lubrication.

Top plastic panel has cleaned up pretty well. Am going to clean the filthy carrying handle, a quick go with IPA and elbow grease shows that it will clean up. Also want to clean the dirty perforated plastic case, plus top & bottom covers, I think all of these will be much harder work.

[Gulliver]

Nice, basic domestic machines. I've had two of those in my time and still own one of the later all white machines which I bought at a jumble sale in the 80s. Last time I had it out I replaced the belts but couldn't get any sound of the amp at all.

[DMcMahon]

Didn't by any chance have the loudspeaker switch on the rear panel inadvertently switched off ?

[DMcMahon]

On off switch/tone control knob is mis-aligned resulting in incomplete physical range of tone control adjustment and 2 on/off operating positions, need to investigate.

[Gulliver]

Originally Posted by DMcMahon

Didn't by any chance have the loudspeaker switch on the rear panel inadvertently switched off ?

I tried that. Unfortunately while I have loads of time right now, the machine is in storage and I can't get to it!

[DMcMahon]

Reference Post #4 many thanks to TowerRadio, who previously gave me a number of Grundig drive belts, one of which I used for the TK 14 flywheel drive to the Take Up spool.

[julie_m]

While most UK manufacturers were supplying crystal mics with their tape recorders, Grundig were supplying condenser mics with some machines and dynamic mics fitted with an integral impedance matching transformer with others.

As this predates the discovery of electrets, the condenser mics required a high voltage power supply on a "spare" pin of the DIN socket ..... which must surely have caused a few surprises

[DMcMahon]

Yesterday had a quick check of recording (just by visual Magic Eye indication) using the Grundig GDM 18 dynamic mic that came with the TK 14 and it worked.

I then tried my lastest Grundig mic acquisition, a lovelly looking (and VGC) GDM 11 but this did not work. I believe this is not a condenser mic so should be wired to pin 1 of the microphone DIN as against pin 3 for condenser mic.

So I need to double check that the GDM 11 is not condenser, it certainly is old enough to be and if not, check it is wired to pin 1.

[DMcMahon]

Got tape counter working, its worm gear was all gummed up.

Ref post # 7 tried to fix the on/off switch - tone control, but found that whatever position I fitted the control knob always ended up with 2 different physical positions where on/off worked and with resultant incomplete range of tone control physical operation.

I think one of my TK 23s is the same. Sometime I need to look at one of the TK 23s that does not exhibit this feature to determine what is different.

[TonyDuell]

Originally Posted by DMcMahon

So I need to double check that the GDM 11 is not condenser, it certainly is old enough to be and if not, check it is wired to pin 1.

I thought the condenser microphones were GCM's and dynamic ones GDM's

Although it almost certainly originally stood for something in German, I remember it as 'Grundig Condenser Microphone' and 'Grundig Dynamic Microphone'

[DMcMahon]

Thank you Tony, yes I am sure you are correct.

My GCM3 mic is a condenser and the German version of it is GKM17, condenser in German being Kondesator, which is also German for capacitor (a condenser being a capacitor of course).

Dynamic in German being Dynamisch.

[DMcMahon]

Tested microphone recording using the GDM 11. As before the Magic Eye showed good record signal, but nothing played back, apart from some loud clicks, plus the original recording was not erased.

So next need to check out the Bias Oscillator and if good then check that the bias signals are getting to the Erase & Record Heads.

I thought things were progressing too well !

[DMcMahon]

Typo error in Post #14:- "Kondesator" should have read "Kondensator".

[Ray_Singh]

Ive got one of these that i rescued from my uncle a long long time ago. He had it for years and one day i noticed it in the bin. I took it home.
It still works and plays well even after being dormant for 25 years. The magic eye needs pressing in to make it work.
If you want me to take any pictures or measure voltages for you, please let me know.

[DMcMahon]

Hello Ray,

Thank you for the offer, I should be OK as I have several TK 23s that are basically the same or very similar.

David

[DMcMahon]

See that Grundig also did GBM microphones, which were ribbon microphones.

Ribbon in German is bändchen, so Grundig Bändchen Mikrofon.

[TonyDuell]

I _think_ those were called GRM's in the UK. I've certainly seen references to a Grundig GRM1 ribbon microphone.