Grundig 2043/W/3D double declutching problem - UK Vintage Radio Repair and Restoration Discussion Forum

Mullard · 22nd Aug 2007, 4:18 pm

No, I haven't gone mad, nor am I in the wrong forum. I recently obtained the Grundig 2043 and discovered that the tuning knob had no effect. At first I thought the problem would be broken drive cords. But no; on removing the back, the drive cords for both AM and FM were intact and turning the tuning knob just spun the flywheel designed to give a smooth tuning operation and rapid travel by spinning. The Grundig is a classic 50’s radio with Mullard valve line up including a tuning indicator. The 3D version includes 3 speakers; 1 facing forwards and 2 mounted 1 each side of the case.

Once the chassis was out I was faced with a typical German solution to driving 2 tuning systems from a single tuning knob. A double clutch system operated by a fork driven from the waveband selector switch (what else would you do?). The flywheel is attached to the tuning shaft, and two pulleys, one either side of the flywheel have two turns of drive cord around them; one for AM and one for FM. The drive cords drive the tuning caps and pointers via a number of idler pulleys. The two pulleys are free to turn on the shaft, and so no motion is transferred to them when the tuning knob is operated. Each of the pulleys has a spring on the shaft that pushes the pulley towards flywheel, and operating the waveband selector causes the pulleys to move into and out of contact with the flywheel. It was clear that this was a clutch mechanism designed to transfer the drive to the appropriate tuning system according to whether an AM waveband was selected or the FM waveband. Unfortunately, the clutches were slipping and consequently there was no drive. Under the chassis is a fork mechanism that presses on a flange machined into each pulley. The fork operates by disengaging the tuning system that is not required by pushing it away from the flywheel against the spring.

The only solution was to disassemble the clutch unit, and before anything was removed, sticky tape was used to prevent the drive cords falling off the pulleys. The operating fork is fixed to the operating shaft by 2 set screws and these were slackened and the fork unit slid clear of the mechanism. Three circlips hold the clutch unit together, and the first of these is on the end of the shaft and the other 2 provide the stops for the pulley/clutch springs. The flywheel is secured to the shaft with a set screw. All clips, washers, plastic bushes, and springs were carefully removed and set down in the order they fit on the shaft to assist with correct reassembly, and the shaft, flywheel, and pulleys removed. Once the parts were on the bench the problem was clear; each of the pulleys had some sort of facing material stuck on it and the flywheel had a set of conical protrusions cast into it. The material on the pulley faces was black and hard, and had probably been soft rubber 50 years ago. The material was glued on and came away easily in one piece. I considered a number of alternative materials to replace the original, and following bench tests with a few candidates (including rubber washers), I decided that leather was the best solution. I used two layers of thick leather with the rough side towards the flywheel and glued them to the clutch faces of the pulleys.

Following reassembly, the flywheel was positioned so that each of the clutch springs was equally compressed and the set screw tightened. With the clutch fork out of position, both clutches engage and I was pleased to note that turning the tuning knob, drove both the AM and FM tuning cords. To reposition the fork, it is necessary to push back one of the pulleys and then tighten the set screws. It took several attempts to get the fork in the right position on the shaft so that the AM and FM pulleys, each moved the same amount as FM and AM wavebands were selected. Finally, the tuning system was working correctly (well at least mechanically).

Next I will look at the rest of the set, but first I must get the service sheet.

Hope this is intersting/useful to someone.
John

newlite4 · 22nd Aug 2007, 4:59 pm

This mechanism is similar to that on the Philips B4X bi-ampli John. Here you have the fork position controlled by wether FM or AM bands are selected on the piano keys, but it controls the position of a dog clutch which either engages one pulley or the other onto the tuning shaft. This mechanism can stiffen-up when the radio in unused but with heat and use, it frees-up.
Neil

kalee20 · 22nd Aug 2007, 5:12 pm

This is generally a good radio, sound is excellent, FM range includes Clasic FM, and sensitivity is good.

It sounds like you have done a good job with the clutches! Mine, incidentally, uses reconstituted cork for the clutch facings - oroginal equipment as far as I know, and I've had it since 1977!

The other job you may need to reconcile yourself to, is replacing the valveholders. Why Grundig used cheap nasty Paxolin valveholders beats me. I had to change all of mine, using McMurdo for all except the ECC85 FM frequency changer, for which I used ceramic.

johnlees · 22nd Aug 2007, 8:40 pm

I have a Philips B3X92A which had a similar clutch problem. I can't remember how I fixed it but it was a simple mechanical problem which needed freeing up.

Mullard · 22nd Aug 2007, 9:13 pm

I have now obtained the R&TV Servicing entry, and according to the drawng shown here, the clutch nlining should be rubber. I tried rubber washers and these didn't seem to gve enough grip and so I assume the originals must have been a coarse rubber sponge (perhaps similar to the solid carpet underlay you see sometmes). This is supported by the pieces I removed that, although now hard, clearly show a granular structure.

John

Keith · 25th Aug 2007, 9:42 pm

I fixed my 2043 clutch by glueing in an additional rubber disc made from a piece of bicycle inner tube. By cutting along a radius of the disc it can be inserted without having to dismantle the clutch assembly. Still working fine.

GJR 11L · 25th Aug 2007, 10:14 pm

I recently fixed a tuning clutch fault on one of my growing number of Graetz sets, the problem here was that rather than being a friction-type clutch, it had a dog clutch with fine, Nylon teeth.

Not to be beaten by this, I shaved each plate down to the base of the teeth and glued pieces of thin rubber sheeting to each, using rubber solution which reacted sufficiently well with the nylon parts to form more than a contact-style bond.

This may be of use to some in place of the cork used for the older types of clutches in these applications.

The rubber comes from some of the places who supply kit-car makers and was originally bought by me to replace the perished and rattly original canvas that sits atop the chassis of my car to insulate the floorboards from the steel beneath.

22nd Aug 2007, 4:18 pm	#1
Mullard Pentode Join Date: Jul 2007 Location: Clophill, Bedfordshire, UK. Posts: 127	Grundig 2043/W/3D double declutching problem No, I haven't gone mad, nor am I in the wrong forum. I recently obtained the Grundig 2043 and discovered that the tuning knob had no effect. At first I thought the problem would be broken drive cords. But no; on removing the back, the drive cords for both AM and FM were intact and turning the tuning knob just spun the flywheel designed to give a smooth tuning operation and rapid travel by spinning. The Grundig is a classic 50’s radio with Mullard valve line up including a tuning indicator. The 3D version includes 3 speakers; 1 facing forwards and 2 mounted 1 each side of the case. Once the chassis was out I was faced with a typical German solution to driving 2 tuning systems from a single tuning knob. A double clutch system operated by a fork driven from the waveband selector switch (what else would you do?). The flywheel is attached to the tuning shaft, and two pulleys, one either side of the flywheel have two turns of drive cord around them; one for AM and one for FM. The drive cords drive the tuning caps and pointers via a number of idler pulleys. The two pulleys are free to turn on the shaft, and so no motion is transferred to them when the tuning knob is operated. Each of the pulleys has a spring on the shaft that pushes the pulley towards flywheel, and operating the waveband selector causes the pulleys to move into and out of contact with the flywheel. It was clear that this was a clutch mechanism designed to transfer the drive to the appropriate tuning system according to whether an AM waveband was selected or the FM waveband. Unfortunately, the clutches were slipping and consequently there was no drive. Under the chassis is a fork mechanism that presses on a flange machined into each pulley. The fork operates by disengaging the tuning system that is not required by pushing it away from the flywheel against the spring. The only solution was to disassemble the clutch unit, and before anything was removed, sticky tape was used to prevent the drive cords falling off the pulleys. The operating fork is fixed to the operating shaft by 2 set screws and these were slackened and the fork unit slid clear of the mechanism. Three circlips hold the clutch unit together, and the first of these is on the end of the shaft and the other 2 provide the stops for the pulley/clutch springs. The flywheel is secured to the shaft with a set screw. All clips, washers, plastic bushes, and springs were carefully removed and set down in the order they fit on the shaft to assist with correct reassembly, and the shaft, flywheel, and pulleys removed. Once the parts were on the bench the problem was clear; each of the pulleys had some sort of facing material stuck on it and the flywheel had a set of conical protrusions cast into it. The material on the pulley faces was black and hard, and had probably been soft rubber 50 years ago. The material was glued on and came away easily in one piece. I considered a number of alternative materials to replace the original, and following bench tests with a few candidates (including rubber washers), I decided that leather was the best solution. I used two layers of thick leather with the rough side towards the flywheel and glued them to the clutch faces of the pulleys. Following reassembly, the flywheel was positioned so that each of the clutch springs was equally compressed and the set screw tightened. With the clutch fork out of position, both clutches engage and I was pleased to note that turning the tuning knob, drove both the AM and FM tuning cords. To reposition the fork, it is necessary to push back one of the pulleys and then tighten the set screws. It took several attempts to get the fork in the right position on the shaft so that the AM and FM pulleys, each moved the same amount as FM and AM wavebands were selected. Finally, the tuning system was working correctly (well at least mechanically). Next I will look at the rest of the set, but first I must get the service sheet. Hope this is intersting/useful to someone. John

22nd Aug 2007, 4:59 pm	#2
newlite4 Octode Join Date: Nov 2003 Location: Bath, Somerset, UK. Posts: 1,806	Re: Grundig 2043/W/3D double declutching problem This mechanism is similar to that on the Philips B4X bi-ampli John. Here you have the fork position controlled by wether FM or AM bands are selected on the piano keys, but it controls the position of a dog clutch which either engages one pulley or the other onto the tuning shaft. This mechanism can stiffen-up when the radio in unused but with heat and use, it frees-up. Neil __________________ preserving the recent past, for the distant future.

22nd Aug 2007, 5:12 pm	#3
kalee20 Dekatron Join Date: Feb 2007 Location: Lynton, N. Devon, UK. Posts: 7,088	Re: Grundig 2043/W/3D double declutching problem This is generally a good radio, sound is excellent, FM range includes Clasic FM, and sensitivity is good. It sounds like you have done a good job with the clutches! Mine, incidentally, uses reconstituted cork for the clutch facings - oroginal equipment as far as I know, and I've had it since 1977! The other job you may need to reconcile yourself to, is replacing the valveholders. Why Grundig used cheap nasty Paxolin valveholders beats me. I had to change all of mine, using McMurdo for all except the ECC85 FM frequency changer, for which I used ceramic.

22nd Aug 2007, 8:40 pm	#4
johnlees Hexode Join Date: Oct 2004 Location: Cheltenham, Gloucestershire, UK. Posts: 283	Re: Grundig 2043/W/3D double declutching problem I have a Philips B3X92A which had a similar clutch problem. I can't remember how I fixed it but it was a simple mechanical problem which needed freeing up. __________________ Now that's the kind of Long Wave I like ! (Severn Bore near Gloucester)

22nd Aug 2007, 9:13 pm	#5
Mullard Pentode Join Date: Jul 2007 Location: Clophill, Bedfordshire, UK. Posts: 127	Re: Grundig 2043/W/3D double declutching problem I have now obtained the R&TV Servicing entry, and according to the drawng shown here, the clutch nlining should be rubber. I tried rubber washers and these didn't seem to gve enough grip and so I assume the originals must have been a coarse rubber sponge (perhaps similar to the solid carpet underlay you see sometmes). This is supported by the pieces I removed that, although now hard, clearly show a granular structure. John

25th Aug 2007, 9:42 pm	#6
Keith Heptode Join Date: Jan 2003 Location: Tewkesbury, Gloucestershire, UK. Posts: 693	Re: Grundig 2043/W/3D double declutching problem I fixed my 2043 clutch by glueing in an additional rubber disc made from a piece of bicycle inner tube. By cutting along a radius of the disc it can be inserted without having to dismantle the clutch assembly. Still working fine. __________________ Keith Yates - G3XGW VMARS & BVWS member http://www.tibblestone.com/oldradios/Old_Radios.htm

25th Aug 2007, 10:14 pm	#7
GJR 11L Heptode Join Date: May 2004 Location: Ellington, Northumberland, UK. Posts: 815	Re: Grundig 2043/W/3D double declutching problem I recently fixed a tuning clutch fault on one of my growing number of Graetz sets, the problem here was that rather than being a friction-type clutch, it had a dog clutch with fine, Nylon teeth. Not to be beaten by this, I shaved each plate down to the base of the teeth and glued pieces of thin rubber sheeting to each, using rubber solution which reacted sufficiently well with the nylon parts to form more than a contact-style bond. This may be of use to some in place of the cork used for the older types of clutches in these applications. The rubber comes from some of the places who supply kit-car makers and was originally bought by me to replace the perished and rattly original canvas that sits atop the chassis of my car to insulate the floorboards from the steel beneath. __________________ John.