Grundig TK120 - UK Vintage Radio Repair and Restoration Discussion Forum

mjb2019 · 11th Oct 2019, 2:07 pm

Hello all,

New to this world as I find myself in possession of an old TK120. I have a few questions as I really don't know how to gauge my expectation of sound quality and also functionality.

Problem one. I have just one original tape reel that has some old recordings. I found the volume has to be played relatively low as it starts to get quite distorted. I'm not sure whether this is down to recording quality or a bigger issue with playback?

Second question. It has a Microphone which I have tried to use. I can see its picking up the from the MIC as the small green tube at the front responds to the MIC when the record is pressed, however it doesn't appear to record anything. Not sure whether this is to do with the tape or there is an issue with the recording functionality.

Any insight would be greatly appreciated.

Thanks, Matt

AndiiT · 11th Oct 2019, 8:59 pm

Hi, at a rough guess I would check the output valve screen grid decoupling electrolytic capacitor. It may be prudent to check/change the power supply electrolytics too.

Andrew

Welsh Anorak · 13th Oct 2019, 11:36 am

I've had this fault which was due to a resistor (I think 150k) in the biasing of the first valve stage. Easily found with a meter, but obviously that depends on your level of experience with valved electronics - there are a few volts lurking around! Andrew's advice is of course valid, as would be a check on the output valve itself - and the speaker. I've not had any trouble with the power supply electrolytics, but it's possible.
If the 'magic eye' jumps about when you press the record button then I suspect your microphone might be faulty. Turn the volume up, then insert the plug while watching the display. If it moves, then I'd suspect the microphone itself.

11th Oct 2019, 2:07 pm	#1
mjb2019 Diode Join Date: Oct 2019 Location: Oxford, Oxfordshire, UK. Posts: 1	Grundig TK120 Hello all, New to this world as I find myself in possession of an old TK120. I have a few questions as I really don't know how to gauge my expectation of sound quality and also functionality. Problem one. I have just one original tape reel that has some old recordings. I found the volume has to be played relatively low as it starts to get quite distorted. I'm not sure whether this is down to recording quality or a bigger issue with playback? Second question. It has a Microphone which I have tried to use. I can see its picking up the from the MIC as the small green tube at the front responds to the MIC when the record is pressed, however it doesn't appear to record anything. Not sure whether this is to do with the tape or there is an issue with the recording functionality. Any insight would be greatly appreciated. Thanks, Matt

11th Oct 2019, 8:59 pm	#2
AndiiT Octode Join Date: Aug 2005 Location: Saltburn-East, Cleveland, UK. Posts: 1,786	Re: Grundig TK120 Hi, at a rough guess I would check the output valve screen grid decoupling electrolytic capacitor. It may be prudent to check/change the power supply electrolytics too. Andrew

13th Oct 2019, 11:36 am	#3
Welsh Anorak Dekatron Join Date: Apr 2005 Location: North Wales, UK. Posts: 6,918	Re: Grundig TK120 I've had this fault which was due to a resistor (I think 150k) in the biasing of the first valve stage. Easily found with a meter, but obviously that depends on your level of experience with valved electronics - there are a few volts lurking around! Andrew's advice is of course valid, as would be a check on the output valve itself - and the speaker. I've not had any trouble with the power supply electrolytics, but it's possible. If the 'magic eye' jumps about when you press the record button then I suspect your microphone might be faulty. Turn the volume up, then insert the plug while watching the display. If it moves, then I'd suspect the microphone itself. __________________ Glyn www.gdelectronics.wales