Grundig TK20 - Belt Replacement Procedure? - UK Vintage Radio Repair and Restoration Discussion Forum

ThermionicIdler · 22nd Apr 2018, 1:13 pm

Hi all,

I'm stumped and would be enormously grateful for some advice please. We bought a Grundig TK20 last week in apparently quite good original shape - however all the belts had perished and snapped so needed replacement.

We got a new belt set from Germany and here is where I've been struggling. I've downloaded all the service manuals I can find (in German) and purchased the two English ones available on this website as well. However, NONE of the service manuals have any kind of documented procedure on how you're supposed to get the belts around the flywheel. I've removed the plastic bearing at the top of the capstan which did leave enough of a gap to thread the smaller belt through (the one that goes from the flywheel to the take-up spool). However, the larger belt which goes from the motor to the flywheel seems slightly too large to go through that gap.

The only way around this seems to be to remove the whole top assembly that has the heads on it - but it's not only the heads that are fixed to this, there seems to be a riveted linkage to the left control switch controlling the position of the pinch roller, and this is also linked up to the left hand spool and down through the chassis to all sorts of microswitches and lord knows what else. I can't believe that doing something as simple as replacing a belt should have to involve dismantling half the mechanics, and I feel really uncomfortable attempting it without any kind of documentation.

Has anyone had any experience replacing the belts on this particular machine? Seems each Grundig tape recorder has a slightly different design of head mounting assembly as well.

ThermionicIdler · 22nd Apr 2018, 7:30 pm

Update - having examined the mechanism more closely, it appears that the lever that I thought was attached to the control knob, isn't! The control knob has a series of cams, and the lever in fact 'rolls over' the cam to enable the positioning of the pinch roller wheel. I was looking from the wrong angle before.

So - it looks like with some care, it should be possible for me to remove that top plate without too much difficulty. Wish me luck!

camtechman · 29th Apr 2018, 9:47 am

Quote:

I've removed the plastic bearing at the top of the capstan.

Hopefully you measured the original gap between the 'bearing' and the capstan as the gap is factory set to specific gap.

If you have the service manual, it should state the gap required for correct running of the flywheel.

If you have set of spark plug feelers they will help you set it up.

22nd Apr 2018, 1:13 pm	#1
ThermionicIdler Retired Dormant Member Join Date: Apr 2018 Location: Derbyshire, UK. Posts: 2	Grundig TK20 - Belt Replacement Procedure? Hi all, I'm stumped and would be enormously grateful for some advice please. We bought a Grundig TK20 last week in apparently quite good original shape - however all the belts had perished and snapped so needed replacement. We got a new belt set from Germany and here is where I've been struggling. I've downloaded all the service manuals I can find (in German) and purchased the two English ones available on this website as well. However, NONE of the service manuals have any kind of documented procedure on how you're supposed to get the belts around the flywheel. I've removed the plastic bearing at the top of the capstan which did leave enough of a gap to thread the smaller belt through (the one that goes from the flywheel to the take-up spool). However, the larger belt which goes from the motor to the flywheel seems slightly too large to go through that gap. The only way around this seems to be to remove the whole top assembly that has the heads on it - but it's not only the heads that are fixed to this, there seems to be a riveted linkage to the left control switch controlling the position of the pinch roller, and this is also linked up to the left hand spool and down through the chassis to all sorts of microswitches and lord knows what else. I can't believe that doing something as simple as replacing a belt should have to involve dismantling half the mechanics, and I feel really uncomfortable attempting it without any kind of documentation. Has anyone had any experience replacing the belts on this particular machine? Seems each Grundig tape recorder has a slightly different design of head mounting assembly as well.

22nd Apr 2018, 7:30 pm	#2
ThermionicIdler Retired Dormant Member Join Date: Apr 2018 Location: Derbyshire, UK. Posts: 2	Re: Grundig TK20 - Belt Replacement Procedure? Update - having examined the mechanism more closely, it appears that the lever that I thought was attached to the control knob, isn't! The control knob has a series of cams, and the lever in fact 'rolls over' the cam to enable the positioning of the pinch roller wheel. I was looking from the wrong angle before. So - it looks like with some care, it should be possible for me to remove that top plate without too much difficulty. Wish me luck!