UK Vintage Radio Repair and Restoration Powered By Google Custom Search Vintage Radio and TV Service Data

Go Back   UK Vintage Radio Repair and Restoration Discussion Forum > Specific Vintage Equipment > Vintage Audio (record players, hi-fi etc)

Notices

Vintage Audio (record players, hi-fi etc) Amplifiers, speakers, gramophones and other audio equipment.

Closed Thread
 
Thread Tools
Old 17th Oct 2019, 9:31 pm   #1
Paul444
Retired Dormant Member
 
Join Date: Oct 2019
Location: Crewe, Cheshire, UK.
Posts: 6
Default Dansette RG31 mains wiring

Hi All,

I've just joined the forum. I've acquired a Dansette RG31 with the old mains twin (white) cable but no plug connected, and I want to check it's working. The unit looks completely original and both are correctly connected to the back of the on/off switch. Which is live and which is neutral?

Thanks.

Last edited by Paul444; 17th Oct 2019 at 9:52 pm. Reason: Grammer
Paul444 is offline  
Old 17th Oct 2019, 10:43 pm   #2
'LIVEWIRE?'
Rest in Peace
 
'LIVEWIRE?''s Avatar
 
Join Date: Mar 2006
Location: N.W. Oxfordshire(Chipping Norton)
Posts: 7,306
Default Re: Dansette RG31 mains wiring

The only way to check is, with no power applied to use an ohmmeter on it's lowest range (The ohms range of either an analogue meter or a DMM ) and check which of the two leads connect to chassis with the switch in the 'on' position. Personally I would replace that flex with a suitable length of modern brown & blue, 3 Amp rated, mains lead, ensuring that the blue wire connects, via the player's on/off switch, to chassis, and then connecting this lead to the Neutral pin of a 13 amp plug. The brown lead should then be connected to the other pole of the player's on/off switch, and to the 'Live' terminal of the 13 Amp plug. Be sure to fit a 3 Amp mains fuse in the plug. By following the above instruction you will ensure that the chassis of the player is always at Neutral potential. This is an important safety precaution.
'LIVEWIRE?' is offline  
Old 18th Oct 2019, 12:09 am   #3
Herald1360
Dekatron
 
Herald1360's Avatar
 
Join Date: Feb 2007
Location: Leominster, Herefordshire, UK.
Posts: 16,528
Default Re: Dansette RG31 mains wiring

As originally designed and supplied the player would have worked OK and been safe enough by the standards of the day with the mains either way round but with old age and possible missing knobs, covers or insulating sleeves on accessible connections it might be possible to touch live wiring or metalwork. The hazard this presents is significantly lower if neutral rather than line is connected to that metalwork!

Edit:

Looked at the circuit here: https://www.radiomuseum.org/r/dansette_rg31rg_3.html

Even in the thumbnail you can see an isolating transformer is used on this particular model so there is no connection between mains lead and chassis/accessible wiring anyway so the set is equally (un)safe either way round. So in short, to answer your original question- "It doesn't matter".

However, being somewhat more complex than a basic one valve amplifier record grinder, this unit, unless it's been properly serviced by someone who is familiar with valve circuits and their problems of old age, will almost certainly need a few (cheap) capacitors replacing to ensure the ongoing health of other much more expensive components. First thing to do is NOT just plug in, turn on and hope!

Let us know your technical expertise level and whether you feel confident about unsoldering and replacing small electronic components
__________________
....__________
....|____||__|__\_____
.=.| _---\__|__|_---_|.
.........O..Chris....O

Last edited by Herald1360; 18th Oct 2019 at 12:23 am. Reason: Checked actual circuit
Herald1360 is offline  
Old 18th Oct 2019, 8:44 am   #4
'LIVEWIRE?'
Rest in Peace
 
'LIVEWIRE?''s Avatar
 
Join Date: Mar 2006
Location: N.W. Oxfordshire(Chipping Norton)
Posts: 7,306
Default Re: Dansette RG31 mains wiring

Apoogies if I misled you, Paul, or any othe readers of this thread. I didn't know, or had forgotten that the RG31 used a mains isolating transformer, but assumed it was a 'live chassis' model, as many old record players are. In those machines my comments in post #2 should be noted, and adhered to. (That'll teach me to check up before posting, won't it??)
'LIVEWIRE?' is offline  
Old 18th Oct 2019, 9:40 am   #5
Edward Huggins
Dekatron
 
Join Date: Sep 2015
Location: Southwold, Suffolk, UK.
Posts: 8,302
Default Re: Dansette RG31 mains wiring

Why not take full advantage of the opportunity to re-wire this and fit a 3 core cable so the unit can be properly earthed? It may also reduce any apparent hum. The Yellow/Green wire can be fitted on to the amplifier chassis using any convenient earthing point.
__________________
Edward.
Edward Huggins is offline  
Old 18th Oct 2019, 9:40 am   #6
Nuvistor
Dekatron
 
Nuvistor's Avatar
 
Join Date: Aug 2013
Location: Wigan, Greater Manchester, UK.
Posts: 9,428
Default Re: Dansette RG31 mains wiring

Need some caution, the radio museum circuit is for a RG30 not an RG31, they could however have the same chassis and circuit.
__________________
Frank
Nuvistor is offline  
Old 18th Oct 2019, 10:12 am   #7
cathoderay57
Nonode
 
Join Date: Oct 2017
Location: Bristol, UK.
Posts: 2,369
Default Re: Dansette RG31 mains wiring

Hi Paul, I restored an RG30 earlier this year. Not sure of the differences between RG30 and RG31. Same valve line-up so the circuits are probably very similar. On the one I repaired the fault was no sound. Two resistors had gone very high. These were R18 (18k) (the dropper resistor across the smoothing capacitors), and R11 (220k) the 6AT6 triode anode load resistor. You'd be wise to check the HT capacitors C18A and C18B and C14. Also C19 if it is a wax paper type or a Hunts black or brown plastic encased capacitor. On mine C19 was ceramic so it was OK. The other thing to check for is an open circuit winding on the output transformer primary (the winding connected to the 6AQ5 anode). On mine the output transformer had been replaced and was OK. Cheers, Jerry
cathoderay57 is offline  
Old 18th Oct 2019, 10:14 am   #8
Herald1360
Dekatron
 
Herald1360's Avatar
 
Join Date: Feb 2007
Location: Leominster, Herefordshire, UK.
Posts: 16,528
Default Re: Dansette RG31 mains wiring

The actual RTVS listing for the RG31 in the '60/'61 volume simply refers to the deck (BSR UA14) and that it is fitted with a similar chassis to the RG30 described in the previous year's volume.


Sooo.... almost certainly isolated chassis but worth a careful check that the mains transformer truly is an isolating type.
__________________
....__________
....|____||__|__\_____
.=.| _---\__|__|_---_|.
.........O..Chris....O
Herald1360 is offline  
Old 18th Oct 2019, 12:33 pm   #9
Techman
Dekatron
 
Techman's Avatar
 
Join Date: Nov 2009
Location: Lincolnshire, UK.
Posts: 4,990
Default Re: Dansette RG31 mains wiring

While I agree with nearly everyone's comments and advice, there's one point that I totally disagree with, and that's suggesting that a completely unskilled person replaces a mains lead - no offence meant to the OP. We know the OP is unskilled to some extent due to the question asked. I also disagree with the fitting of an earth, particularly by an unskilled person, plus the legal implications of 'modification' in this area. Perhaps the OP can let us know his level of skill so that it may be possible to guide him safely, should the existing mains lead be in poor condition, regardless of whether it's the old, unsheathed type or not.
Techman is offline  
Old 18th Oct 2019, 12:49 pm   #10
'LIVEWIRE?'
Rest in Peace
 
'LIVEWIRE?''s Avatar
 
Join Date: Mar 2006
Location: N.W. Oxfordshire(Chipping Norton)
Posts: 7,306
Default Re: Dansette RG31 mains wiring

Fair comment, Techman, but , speaking as someone with 50 years experience in repairing, constructing and servicing radio and audio equipment, I have always understood that anything fitted with a proper double wound mains transformer, which completely isolates the circuits powered from the mains can be safely earthed, and maybe should be earthed, subject to the insulation of the by now over 50 year old mains Tx being in good order. I also accept that any modification opens up a legal minefield. Whether or not an earthed mains lead could or should be fitted, I always replace those old twin leads with a modern sheathed mains lead as I said in post # 2.
'LIVEWIRE?' is offline  
Old 18th Oct 2019, 12:58 pm   #11
Paul444
Retired Dormant Member
 
Join Date: Oct 2019
Location: Crewe, Cheshire, UK.
Posts: 6
Default Re: Dansette RG31 mains wiring

Thanks for all the replies. I’m a complete novice when it comes to radio electricals.

I’m using the setting on my multimeter as shown. With the power switch in the “on” position I tested the wires for continuity, and received a reading of 0.1 on each side of the On/Off switch with the corresponding wires, so know which wire goes to which terminal. However, beyond this I still don’t know which wire is which or what else to test. When I connect one end of the meter to either the metal casing of the on/off switch, or the vertical metal plate in the photo behind the switch, I don’t receive a reading. So, where is the chassis to which I need to connect?

I would like to rewire this with modern cable, but need to establish which is live and which is neutral.
Attached Thumbnails
Click image for larger version

Name:	Dansette 003.jpg
Views:	81
Size:	53.2 KB
ID:	192083   Click image for larger version

Name:	Dansette 002.jpg
Views:	159
Size:	78.8 KB
ID:	192084  
Paul444 is offline  
Old 18th Oct 2019, 1:09 pm   #12
AC/HL
Dekatron
 
AC/HL's Avatar
 
Join Date: Nov 2003
Location: Heckmondwike, West Yorkshire, UK.
Posts: 9,637
Default Re: Dansette RG31 mains wiring

There is no polarity here. There may or may not be a very slight difference in hum level one way, but that's all. A like for like replacement with a two core sheathed cable would be quite legal if you want to do it, but unless the existing one is damaged there isn't much to be gained. It's a vintage player!
AC/HL is offline  
Old 18th Oct 2019, 1:43 pm   #13
'LIVEWIRE?'
Rest in Peace
 
'LIVEWIRE?''s Avatar
 
Join Date: Mar 2006
Location: N.W. Oxfordshire(Chipping Norton)
Posts: 7,306
Default Re: Dansette RG31 mains wiring

I apologise (again!) for misleading you, Paul. In sets fitted, as the RG31 is, with an isolating mains transformer, there will be no connection between either side of the mains and the chassis or negative rail. This only applies to the 'live chassis' players & radios which do not employ a mains transformer.
'LIVEWIRE?' is offline  
Old 18th Oct 2019, 2:13 pm   #14
Paul444
Retired Dormant Member
 
Join Date: Oct 2019
Location: Crewe, Cheshire, UK.
Posts: 6
Default Re: Dansette RG31 mains wiring

All the comments are constructive, I'm grateful for them and not offended. The original cable has a section covered with tape, having been "repaired" in the past, so at the least I'll unwind it and check it. Thanks Livewire, being a novice I didn't initially understand your observation.

Can I therefore go ahead and connect the wires to a 3 amp plug in either order to test it?
Paul444 is offline  
Old 18th Oct 2019, 2:16 pm   #15
AndiiT
Octode
 
AndiiT's Avatar
 
Join Date: Aug 2005
Location: Saltburn-East, Cleveland, UK.
Posts: 1,786
Default Re: Dansette RG31 mains wiring

Hi, many players of this vintage whether live or isolated chassis used copper strands in the cable for the line/live lead and silver strands for the neutral.

On the subject of fitting three - core leads to mains isolated equipment which was originally fitted with a two - core lead, I have seen advice elsewhere in these forums that fitting a three - core lead may cause problems with the mains transformer due to the possibility of insulation breakdown (I think) - I'm not sure if anyone has actually experienced such after doing so though.

Regards

Andrew
AndiiT is online now  
Old 18th Oct 2019, 2:42 pm   #16
Paul444
Retired Dormant Member
 
Join Date: Oct 2019
Location: Crewe, Cheshire, UK.
Posts: 6
Default Re: Dansette RG31 mains wiring

Thanks Andrew, this is the case. Having unravelled the tape, the "repair" consisted of twisting wires together (see photos). I'll test it later and report back.
Attached Thumbnails
Click image for larger version

Name:	Dans2 001.jpg
Views:	96
Size:	74.9 KB
ID:	192091   Click image for larger version

Name:	Dans2 002.jpg
Views:	103
Size:	84.2 KB
ID:	192092  
Paul444 is offline  
Old 18th Oct 2019, 2:51 pm   #17
'LIVEWIRE?'
Rest in Peace
 
'LIVEWIRE?''s Avatar
 
Join Date: Mar 2006
Location: N.W. Oxfordshire(Chipping Norton)
Posts: 7,306
Default Re: Dansette RG31 mains wiring

One relevant observation-I recently repaired a Dansette Conquest Auto Mk1, which, although a different model, has a 2-stage amplifier and an isolated chassis, with a Mains Transformer. This had been fitted from new with a 3-core mains lead, so the chassis was earthed from the start. Having Said that I take the point about possible insulation breakdown in the mains transformer, though I've not experienced this. It may be wisest, and, as Bill (AC/HL) noted, perfectly legal, to fit a sheathed, colour coded, two-core mains lead.
'LIVEWIRE?' is offline  
Old 18th Oct 2019, 3:06 pm   #18
John10b
Nonode
 
Join Date: Nov 2016
Location: Aberaeron, Ceredigion, Wales, UK.
Posts: 2,869
Default Re: Dansette RG31 mains wiring

Hi Paul444 you need to replace the damaged mains lead with a two core lead ( I know there is some difference of opinion regarding two core or three core) as you wish to test it.
I am concerned that you are a “novice” but provided you understand the dangers of dealing with mains electricity and perhaps do a little studying before you start then connecting to the mains should be ok.
There is plenty of information provided in this forum for you to read and study.
This is not intended to put you off but for your own safety.
Cheers
John
John10b is offline  
Old 18th Oct 2019, 3:28 pm   #19
Herald1360
Dekatron
 
Herald1360's Avatar
 
Join Date: Feb 2007
Location: Leominster, Herefordshire, UK.
Posts: 16,528
Default Re: Dansette RG31 mains wiring

Quote:
Originally Posted by Paul444 View Post
Thanks Andrew, this is the case. Having unravelled the tape, the "repair" consisted of twisting wires together (see photos). I'll test it later and report back.
Yup, that's a bodge, not a repair, and a very good reason to replace the mains lead. The type you need is the sheathed flat twin two core (brown and blue) rated at 3A (typically sold for table lamps and the like). Get a 3A fuse for the plug too if one isn't already fitted.

To fit it properly you'll need to solder the wires to the switch tags, but if there's sufficient of the old wire in good condition inside and the new wire is suitably strain relieved where it enters the box, you could use a two way piece of terminal block (choc bloc) to join the new to the old inside the box. Dress the wires so that they are safely clear of anything that moves or gets hot! As already discussed it doesn't matter which way round you make the connections.

Use a suitable small sized terminal block (5A rated is fine), strip all the wire ends back about 10mm, twist the ends then fold each bare wire neatly back on itself. Insert each wire in turn carefully into its terminal- you want the insulation to end just before the clamping screw, neither under it nor more than maybe 1mm out from it so that when tighted down it all looks neat and tidy.

A photo of the finished job will soon attract comment if it doesn't look right!
__________________
....__________
....|____||__|__\_____
.=.| _---\__|__|_---_|.
.........O..Chris....O
Herald1360 is offline  
Old 18th Oct 2019, 3:34 pm   #20
dave walsh
Dekatron
 
Join Date: Jan 2006
Location: Ramsbottom (Nr Bury) Lancs or Bexhill (Nr Hastings) Sussex.
Posts: 5,814
Default Re: Dansette RG31 mains wiring

As suggested in post 3* Paul, it might be better to go cautiously. Even if it works there could be consequences for aged components! Some people use a lamp limiter....a bulb in series [ie between one of the cables and the plug]. If there is a dead short or other problem the bulb lights up protecting the unit itself from the heavy current. It all depends on what you intend to do, start a new hobby or just get one item working.

For Info-
The confusion over the mains lead was because very many items dating back to the fifties and sixties did not have a mains transformer. An alternative circuit was used to simplify things and reduce the manufacturing cost as the Tr might well be the most expensive item. The drawback is that the chassis is then connected to mains neutral but will be live if the wires are reversed at the plug. Because the works would be well insulated and isolated it was only really a problem if there was any direct access to the metal work [eg when attempting a repair]. That might be the reason why the LC mains cable is often not marked or coloured to ID it plus and negative. The player will work either way. To us, an early record player without an earth lead [usually] suggests a "live chassis" model [as "live" wire said at post 4*].

Your Dansette DOES, in fact, appear to have a transformer so my "live" comments are for general background only. With a transformer in place, the polarity in the plug is even less significant and [again] the wires are not necessarily marked [as in your case].

As Andrew says, there are differing opinions about retro-fitting an earth lead to equipment that didn't have one in the first place but that's another kettle of fish. The main priority is always safety! There is a very good clear and simple guide to restoration and repair written by the site owner here and you can check out various postings about Lamp Limiters etc, if putting one together may be useful to you long term.

Dave W

Last edited by dave walsh; 18th Oct 2019 at 3:39 pm.
dave walsh is offline  
Closed Thread

Thread Tools



All times are GMT +1. The time now is 4:27 pm.


All information and advice on this forum is subject to the WARNING AND DISCLAIMER located at https://www.vintage-radio.net/rules.html.
Failure to heed this warning may result in death or serious injury to yourself and/or others.


Powered by vBulletin®
Copyright ©2000 - 2024, vBulletin Solutions, Inc.
Copyright ©2002 - 2023, Paul Stenning.