Jump to content
 

H&M Duette - help with accessory plug sizes


Graham108
 Share

Recommended Posts

I'm using an old H&M Duette which must be around 50 years old now. Only one of the transformers works, which is OK for me, and I've just tested the 12v accessory connections and they work as well. But I'm really in need of knowing what type / size of plug should be used for a tight fit please.

Link to post
Share on other sites

  • RMweb Premium
40 minutes ago, bartram108 said:

I'm using an old H&M Duette which must be around 50 years old now. Only one of the transformers works, which is OK for me, and I've just tested the 12v accessory connections and they work as well. But I'm really in need of knowing what type / size of plug should be used for a tight fit please.

I have an old H&M catalogue which shows that they were once available, but it doesn't give the size!

 

Usually banana type plugs, the normal size of which are 4mm diameter.

Link to post
Share on other sites

One side failing sounds ominous.  Do the AC and DC uncontrolled outputs both work?   If so its probably the rheostat wire support which may be asbestos has disintegrated. No big deal but I would have the top off and do a visual test on the internal wiring.

The more common fail is the rectifiers, selenium? fail. There are some excellent rectifiers about 12 amp on eBay for about £2 which bolt straight in and work fine just using the case as a heat sink.   You could use a 2 Amp for 75p but you need a £3 heat sink so to misquote Mr pres dent  its Fake Economy.      There was some lethal insulation around circa 1975 which sort of falls off as if its been attacked by acid.  We had some in some UK made flourescent lamps made 1975, had to scrap all 16 or so.  In many cases the 1950s insulation seems fine but I still change it if there is any doubt.

Link to post
Share on other sites

19 hours ago, DavidCBroad said:

One side failing sounds ominous.  Do the AC and DC uncontrolled outputs both work?   If so its probably the rheostat wire support which may be asbestos has disintegrated. No big deal but I would have the top off and do a visual test on the internal wiring.

The more common fail is the rectifiers, selenium? fail. There are some excellent rectifiers about 12 amp on eBay for about £2 which bolt straight in and work fine just using the case as a heat sink.   You could use a 2 Amp for 75p but you need a £3 heat sink so to misquote Mr pres dent  its Fake Economy.      There was some lethal insulation around circa 1975 which sort of falls off as if its been attacked by acid.  We had some in some UK made flourescent lamps made 1975, had to scrap all 16 or so.  In many cases the 1950s insulation seems fine but I still change it if there is any doubt.

Not had chance to test the AC output yet - will try later.

 

Thanks for the other replies - I'll check size with a drill bit (with the unit unplugged!) and I'll get some appropriate plugs from my local electrical shop (if it's open again yet).

Link to post
Share on other sites

19 hours ago, DavidCBroad said:

"... asbestos has disintegrated. No big deal ..."

I agree with the rest of the post but the quoted 2 phrases above don't seem to fit together very well.  If the part is asbestos and has disintegrated I'd junk (I mean dispose responsibly) the controller and buy or use something less harmful.

Link to post
Share on other sites

The duette has a split winding transformer, one winding used for the DC output and one controller, and the other transformer winding used for the AC output and the other controller.

 

'Wander' plugs were the plugs to use for this, and you can probably make 3mm plugs fit by opening them out a little. 1/8" is 3.175mm so not much bigger.

 

I think there might be a little opportunity here to 3D print a suitable plug based around 1/8" brass cotter pins. much like the originals were made.

Link to post
Share on other sites

  • 2 weeks later...

OK so I've now checked the AC outlet and it's working fine. Bu I have another question - which of the sockets are +ve and which -ve please? There's nothing on the unit to identify this and I wouldn't want to wire anything up the wrong way and cause a problem somewhere.

Link to post
Share on other sites

I assume your question regarding +ve and -ve refers to the DC sockets (otherwise the question makes no sense). On mine the +ve is the rear most one (which seems counter intuitive). One assumes they were all the same

Edited by JeremyC
Link to post
Share on other sites

On 10/07/2020 at 17:45, JeremyC said:

I assume your question regarding +ve and -ve refers to the DC sockets (otherwise the question makes no sense). On mine the +ve is the rear most one (which seems counter intuitive). One assumes they were all the same

Many thanks for the info

Link to post
Share on other sites

  • 7 months later...

If you are going to mess about with the insides of a H&M Duettee, be aware that the rheostat is wound on something that looks awfully like flaky asbestos. It is actually described as asbestos in a user manual, but in those days, "asbestos" was sometimes used generically for any heat resistance mat material.

 

image.png.bf032f047732d83efc35ec187df3b79d.png

Edited by Dave B
add a word
Link to post
Share on other sites

  • RMweb Premium
7 hours ago, Dave B said:

If you are going to mess about with the insides of a H&M Duettee, be aware that the rheostat is wound on something that looks awfully like flaky asbestos. It is actually described as asbestos in a user manual, but in those days, "asbestos" was sometimes used generically for any heat resistance mat material.

 

image.png.bf032f047732d83efc35ec187df3b79d.png

For the sake of safety, anything that 'looks like' asbestos, should be treated as if it is asbestos.

 

The answer is for someone to pay for one to be tested. However the problem is that proper testing would cost vastly more than the controller is worth!

  • Agree 1
Link to post
Share on other sites

  • RMweb Premium
On 24/06/2020 at 03:55, Tony Cane said:

In the good old days we (my Dad really) used to push the wire into the hole and hold it there with half a matchstick (used, generally).

Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share

×
×
  • Create New...