Grundig Tape Recorder Earthing - UK Vintage Radio Repair and Restoration Discussion Forum

tele919er · 2nd Apr 2017, 4:20 pm

Hi

I recently started to refurbish 1960s Tape Recorders as a hobby. The ones I have up to now have all been UK models but I recently purchased a Grundig TK27L which unlike the other Grundigs I have, was made in Germany. It has a two pin plug with only two wires and no earth whereas a similar TK17L UK model has an earth wire connected to the chassis. I was thinking of replacing the two wires with a 3 wire flex and UK plug and connecting the earth wire to the chasis as the TK17L. What do you think?

Tractorfan · 2nd Apr 2017, 8:59 pm

Hi,
A lot of European tape recorders, and other audio stuff, were supplied with two core mains leads without problems, while the UK equivalents had three core flex. Perhaps because Europe had circuit breakers and earth leakage devices long before the UK, which still had fuses? (Just my thoughts, I could well be wrong.)
I can't see a problem fitting an earth myself.
Cheers, Pete.

McMurdo · 2nd Apr 2017, 10:54 pm

If it's not double insulated but has conductive parts that may become live in the event of a fault, then it should be earthed. It might have been ok in the 60's but insulation does degrade.
Some pre-Beab 'which?' tests of all sorts of appliances showed up similar problems with imported appliances including non standard mains leads, missing or loose earths and casings which were actually live out of the box.

This is a seperate issue from the ac/dc live chassis thing which is discussed at great length (ad nauseam?) in other threads.

ricard · 3rd Apr 2017, 1:29 pm

I know there have been discussions on German forums regarding the use for unearthed apparatus in modern electrically earthed environments. The discussion that comes to mind was in regard to model railways, but the same electrical conditions apply to any type of equipment.

Germany had a largely unearthed mains in homes at one point (e.g. the 1950s), however, now everything is earthed since a while back. The consensus in Germany seems to be that it is essentially illegal to operate this equipment in a modern environment. Since the equipment was originally not earthed, adding an earthed mains lead constitutes a non manufacturer approved modification of the apparatus. And replacing the original non earthed mains plug (which in continental Europe won't fit in an earthed receptacle) not only constitutes a modification of the apparatus but also is dangerous in that the only non earthed equipment that may be connected to the mains must be double insulated, which these old machines are not.

In practice, adding an earthed mains cord should be fine of course. But if something does go wrong (electrical shock, fire, etc), I wonder if change of mains cord would affect the issue of who is to blame, regardless of whether the modification could be considered the reason for the mishap. Then again, old equipment with potential isolation breakdown in various components must also be considered a risk per se.

As for why the earthing requirements vary between countries, I think it's simply a question of different countries adopting different policies. Sweden where I live used to be like Germany in that most rooms in a house would be unearthed, with only the kitchen and other potentially damp areas requiring earthing (and no outlets were allowed in bath rooms). In those days, there were no circuit breakers or ground-fault interrupters in residential areas, only ordinary fuses in a centrally mounted fuse box. Today, all new installations must be earthed and the fuse box fitted with ground-fault interrupters, however, it is not necessary to upgrade old installations, and in the apartment where I live (built in the 1950s) partial upgrading of the electrical system has left some rooms earthed and some not, with the fuses in the fuse box being replaced by ground-fault interrupters.

On the other hand, there seems to have been more stringent requirement on equipment that was connected to the mains here in Sweden. Looking at vintage equipment (say from the 1950s and 1960s) there are often special Swedish versions of radios and tape recorders which have extra fuses in the mains and anode circuits. I would assume this was mainly for fire prevention, keeping the amount of energy available down to a limit.

2nd Apr 2017, 4:20 pm	#1
tele919er Retired Dormant Member Join Date: Mar 2011 Location: London, UK. Posts: 7	Grundig Tape Recorder Earthing Hi I recently started to refurbish 1960s Tape Recorders as a hobby. The ones I have up to now have all been UK models but I recently purchased a Grundig TK27L which unlike the other Grundigs I have, was made in Germany. It has a two pin plug with only two wires and no earth whereas a similar TK17L UK model has an earth wire connected to the chassis. I was thinking of replacing the two wires with a 3 wire flex and UK plug and connecting the earth wire to the chasis as the TK17L. What do you think?

2nd Apr 2017, 8:59 pm	#2
Tractorfan Dekatron Join Date: Mar 2008 Location: St. Frajou, l'Isle en Dodon, Haute Garonne, France.(Previously: Ellesmere Port, Cheshire, UK.) Posts: 3,183	Re: Grundig Tape Recorder Earthing Hi, A lot of European tape recorders, and other audio stuff, were supplied with two core mains leads without problems, while the UK equivalents had three core flex. Perhaps because Europe had circuit breakers and earth leakage devices long before the UK, which still had fuses? (Just my thoughts, I could well be wrong.) I can't see a problem fitting an earth myself. Cheers, Pete. __________________ "Hello?, Yes, I'm on the train, I might lose the signal soon as we're just going into a tunn..."

2nd Apr 2017, 10:54 pm	#3
McMurdo Dekatron Join Date: Jun 2009 Location: Staffordshire Moorlands, UK. Posts: 5,271	Re: Grundig Tape Recorder Earthing If it's not double insulated but has conductive parts that may become live in the event of a fault, then it should be earthed. It might have been ok in the 60's but insulation does degrade. Some pre-Beab 'which?' tests of all sorts of appliances showed up similar problems with imported appliances including non standard mains leads, missing or loose earths and casings which were actually live out of the box. This is a seperate issue from the ac/dc live chassis thing which is discussed at great length (ad nauseam?) in other threads. __________________ Kevin

3rd Apr 2017, 1:29 pm	#4
ricard Octode Join Date: Mar 2006 Location: Lund, Sweden Posts: 1,632	Re: Grundig Tape Recorder Earthing I know there have been discussions on German forums regarding the use for unearthed apparatus in modern electrically earthed environments. The discussion that comes to mind was in regard to model railways, but the same electrical conditions apply to any type of equipment. Germany had a largely unearthed mains in homes at one point (e.g. the 1950s), however, now everything is earthed since a while back. The consensus in Germany seems to be that it is essentially illegal to operate this equipment in a modern environment. Since the equipment was originally not earthed, adding an earthed mains lead constitutes a non manufacturer approved modification of the apparatus. And replacing the original non earthed mains plug (which in continental Europe won't fit in an earthed receptacle) not only constitutes a modification of the apparatus but also is dangerous in that the only non earthed equipment that may be connected to the mains must be double insulated, which these old machines are not. In practice, adding an earthed mains cord should be fine of course. But if something does go wrong (electrical shock, fire, etc), I wonder if change of mains cord would affect the issue of who is to blame, regardless of whether the modification could be considered the reason for the mishap. Then again, old equipment with potential isolation breakdown in various components must also be considered a risk per se. As for why the earthing requirements vary between countries, I think it's simply a question of different countries adopting different policies. Sweden where I live used to be like Germany in that most rooms in a house would be unearthed, with only the kitchen and other potentially damp areas requiring earthing (and no outlets were allowed in bath rooms). In those days, there were no circuit breakers or ground-fault interrupters in residential areas, only ordinary fuses in a centrally mounted fuse box. Today, all new installations must be earthed and the fuse box fitted with ground-fault interrupters, however, it is not necessary to upgrade old installations, and in the apartment where I live (built in the 1950s) partial upgrading of the electrical system has left some rooms earthed and some not, with the fuses in the fuse box being replaced by ground-fault interrupters. On the other hand, there seems to have been more stringent requirement on equipment that was connected to the mains here in Sweden. Looking at vintage equipment (say from the 1950s and 1960s) there are often special Swedish versions of radios and tape recorders which have extra fuses in the mains and anode circuits. I would assume this was mainly for fire prevention, keeping the amount of energy available down to a limit.