Grundig TK14 Record Problem Fixed. - UK Vintage Radio Repair and Restoration Discussion Forum

Phantomrose1999 · 29th Jun 2019, 11:27 am

I got another one, a beautiful two tone TK14, and while it played, it did not record well. Two problems.

1) Not erasing the previous contents
2) New content very heavily distorted.

Short answer

1) A dry joint at near the Erase head, prevented the bias signal reaching the Erase head, thus not Erasing the previous content.

2) There seemed to be a very high voltage going to the Record / Playback head, which was saturating the head and causing distortion. It took a while to figure this out, but in the end just adjusing C19, until i got around 15 volts at the Record / Play back head got it recording beautifuilly

There are many CRO video's as i went through the process of fixing it. Hope these video show others what they should get at the Record / Playback and Erase heads for a Grunding Reel to Reel to record properly.

https://www.youtube.com/watch?v=0nuEoxr7azw

The above is Part 1, there are 4 parts in total.

martin.m · 2nd Jul 2019, 11:46 am

Well done on getting the TK14 working again, they are well engineered machines and don't usually suffer from leaky capacitors like some of the 1950s Grundigs. No erase and distorted recordings are symptoms of the bias oscillator not running. In the UK there doesn't seem to be a huge interest in domestic tape recorders but I love them. As a teenager in the 60s, all my music was on reels of tape. Four LPs on a five and three quarter inch reel, mono of course.

Ray_Singh · 5th Jul 2019, 8:12 pm

I have just dug out my old Grundig TK14 out of my loft on reading your thread. Its been up there for 15 years and i didnt have good hopes for it.

It fired up straight away and plays lovely. The only thing that has stopped working is the "Magic Eye", but if i press on the plastic body just above the magic eye, it works.

I will investigate.

A lovely machine.

ricard · 8th Jul 2019, 6:20 am

Sounds like a bad connection in the corresponding valve socket. Should be an easy fix.

29th Jun 2019, 11:27 am	#1
Phantomrose1999 Hexode Join Date: Mar 2008 Location: Melbourne, Victoria, Australia Posts: 289	Grundig TK14 Record Problem Fixed. I got another one, a beautiful two tone TK14, and while it played, it did not record well. Two problems. 1) Not erasing the previous contents 2) New content very heavily distorted. Short answer 1) A dry joint at near the Erase head, prevented the bias signal reaching the Erase head, thus not Erasing the previous content. 2) There seemed to be a very high voltage going to the Record / Playback head, which was saturating the head and causing distortion. It took a while to figure this out, but in the end just adjusing C19, until i got around 15 volts at the Record / Play back head got it recording beautifuilly There are many CRO video's as i went through the process of fixing it. Hope these video show others what they should get at the Record / Playback and Erase heads for a Grunding Reel to Reel to record properly. https://www.youtube.com/watch?v=0nuEoxr7azw The above is Part 1, there are 4 parts in total.

2nd Jul 2019, 11:46 am	#2
martin.m Hexode Join Date: Mar 2018 Location: Bishop Auckland, County Durham, UK. Posts: 373	Re: Grundig TK14 Record Problem Fixed. Well done on getting the TK14 working again, they are well engineered machines and don't usually suffer from leaky capacitors like some of the 1950s Grundigs. No erase and distorted recordings are symptoms of the bias oscillator not running. In the UK there doesn't seem to be a huge interest in domestic tape recorders but I love them. As a teenager in the 60s, all my music was on reels of tape. Four LPs on a five and three quarter inch reel, mono of course. __________________ Regards Martin Last edited by martin.m; 2nd Jul 2019 at 11:49 am. Reason: Clarity

5th Jul 2019, 8:12 pm	#3
Ray_Singh Pentode Join Date: Jun 2019 Location: Marlborough, Wiltshire, UK. Posts: 179	Re: Grundig TK14 Record Problem Fixed. I have just dug out my old Grundig TK14 out of my loft on reading your thread. Its been up there for 15 years and i didnt have good hopes for it. It fired up straight away and plays lovely. The only thing that has stopped working is the "Magic Eye", but if i press on the plastic body just above the magic eye, it works. I will investigate. A lovely machine.

8th Jul 2019, 6:20 am	#4
ricard Octode Join Date: Mar 2006 Location: Lund, Sweden Posts: 1,632	Re: Grundig TK14 Record Problem Fixed. Sounds like a bad connection in the corresponding valve socket. Should be an easy fix.