Tandberg 6000X Earthed?
 

Hi All,
I have a rather non technical question. I have just bought a Tandberg 6000X Reel to Reel tape machine via the internet. I am hoping to digitize some 7 inch tapes recorded the 1980's when I had a Grundig machine.
My question is, when cleaning the machine I noticed that the earth wire on the mains lead is cut off short of the mains plug. Should this machine be earthed, or has someone replaced the mains lead with a 3 core one instead of a two core?
I remember back in the day that an earth wire was sometimes disconnected on a peace of band equipment to prevent an earth loop hum, I don't know if that's a possibility here.
I won't be plugging the 6000X into the mains until I'm certain.
Many Thanks.

Re: Tandberg 6000X Earthed?
 

I have examined the mains leads of 3 of my Tandbergs and all of them are two-core.

Re: Tandberg 6000X Earthed?
 

A large number of R2Rs only come (as built) with 2 core mains flex/cable, particularly from continental Europe, the majority of these are not double insulated.

Where practical I always convert to 3 core mains cable and connect the earth wire to the chassis metalwork and of course convert the often fitted 2 pin plugs to UK 3 pin.

This is for my own peace of mind safety wise, particularly as I do a lot of live working inside them (live working only suitable if one is competent and then only with extreme care).

The only exception to this, to my mind would be on the very ancient and rare recorders that have a live chassis, I have never seen one but have heard of a few.

My 6000X (model 6021X) actually came with a 3 core mains cable with the earth connected to chassis metalwork, so presumably done by a previous owner. Have never experienced earth loop hum with any 2 to 3 core converted R2R.

I personally would strongly recommend earthing it and would be surprised if you subsequently have a hum problem.

Update - And check that the earth wire does internally connect to chassis metalwork.

David

Re: Tandberg 6000X Earthed?
 

Many thanks for your replies. I can only assume that someone has replaced the mains lead with 3 core flex, and didn't use the earth. think I will get a new 3 core lead fitted.
I haven't had any earth loop hum on this machine, I just wondered if a previous owner had taken the earth off for that purpose as it seems these machines could be used by musicians on stage. I could try to contact the previous owner via Gumtree.
Best Regards, Barry

Re: Tandberg 6000X Earthed?
 

I know safety standards were more relaxed years ago but how were such continental machines considered safe considering the amount of metalwork exposed?

Re: Tandberg 6000X Earthed?
 

I had a 6041X from new and that had a three core lead.

I have also had four from the 3300 series and all had 3 core as original.

Often in multi equipment setup only one item, usually the amplifier, would have the earth connected to prevent hum loop

Re: Tandberg 6000X Earthed?
 

All my series 15 units came with 3-core leads. I have a series 12, of roughly similar vintage, bought in Europe which has a 2-core mains lead and moulded plug. So it clearly depends on country of origin.

In Europe you can still find unearthed schuko-style mains sockets in vast numbers of properties. In our place the schukos are unearthed apart from in the kitchen.

Re: Tandberg 6000X Earthed?
 

Every Tandberg I have looked at/had through my hands has had 2 core cable either blue black (early) or blue brown (later harmonised).
I suspect 3 core varieties are "home grown"
A lot of people, me included, fit 3 core for current safety standards, but in a lot of cases is not necessary as the metalwork is earthed via the interconnects.
I have fitted a 3 pin IEC to my Revox B77 MkII but added an earth lift switch, and done similar to my 465B so I can work on live chassis with some impunity:o

John

Re: Tandberg 6000X Earthed?
 

I think it varies both depending on country and time frame. I've had a few series 15's over the years, all manufactured for and sold for the Swedish market, and the mains leads were 2-core up to some point, after which they went to 3-core, but even on the 2-core machines there is an obvious earth terminal intended for a 3-core connection.

Earthing in Europe varies between countries. In Germany, eathing is mandatory, in fact, it is not legal to operate unearthed equipment that is not double insulated (i.e. has an unearthed schuko, it is safe and legal to operate double insulated equipment which has a 'flat' two-pin Euro connector). In Sweden where I live, up to some point, I think in the late 1990's or so, earthing was only mandatory in kitchens, bathrooms, and other locations exposed to water. Some premises have an additional room with earthed outlets, intended for operating computers and other equipment where one is expected be in contact with them for long periods of time. Today I think earthing is mandatory in all newly built premises in this country.

Regarding earthing and exposed metalwork, as I understand it, the safety of such equipment is partly based on the fact that it is operated in a room in which there is no exposed grounding points, ergo, you can't get an electric shock from touching said equipment because there is no exposed ground for the current to flow to. Radiators are grounded, but also covered in paint, i.e. isolated (yes, I know that is debatable). The question of an electrical fault in two pieces of equipment is another issue, I think it is considered a 'double fault', i.e. much more unlikely than a 'single fault'.

The dubious nature of this 'isolated room' concept is one of the reasons earthing is becoming mandatory in more and more countries.

Finally, I'm not sure this point was clear to everyone in this thread, ground loops are not a problem when operating equipment in isolation, but when connecting together several pieces of equipment, i.e. a sound system with audio interconnects between the components, an electrical loop will be formed between the ground wire of the audio and the earth wire in the mains wiring. The loop will be susceptible to the mains magnetic field, and will induce hum into the audio channels of said equipment due to the small but sufficient potential difference that is created due to the current flowing in the loop. Often, this effect ground loops can be minimized by relocating cables so that the area of the loop is minimized.

Re: Tandberg 6000X Earthed?
 

One of the Which? reviews of the 1960's checked the electrical safety of tape recorders and several imported ones failed insulation breakdown tests or were rejected as 'not recommended' because there was exposed metalwork that could become live in the event of a fault. There was even one that gave the user a shock when it was being reviewed. The advent of BEAB did alot for safety!

Re: Tandberg 6000X Earthed?
 

Thanks Kevin.