H&M Duette N/474 Information requested

[petertg]

I have an H&M Duette N/474 controller which has failed. Only the 16V A.C. uncontrolled outlets give a correct reading. All the D.C. outlets give a reading of 1V. I believe that this appliance was purchased in 1972, on one of our sporadic trips to the U.K., because it seems unlikely to be 1975 or 1981, when I purchased other items.

My question is: does anyone have a wiring disgram of this appliance, or know where I can get one?

Also, in the light of what is said above, can anyone suggest where the failure might lie?

Apart from this I read a previous thread concerning this appliance and obtained information of the half wave/full wave and high/low resistence features of which I was unaware.

[Gordon H]

As you are getting AC readings but not DC, I suspect the rectifiers have failed.

[TheSignalEngineer]

Failed rectifers was the reason why quite a few of these died. The other problem with old controllers like these is that they can suffer from insulation breakdown.

[DCB]

Binning it is probably the optimum but I put a pair of 15 amp bridge rectifiers in mine to keep it going for a bit longer. The big bridge rectifiers are not so critical on heat sinks as the smaller ones  

The resistance mat speed control is really poor though, trains race downhill and stop when faced with an uphill slope the older H and M variable transformers are vastly superior.

[petertg]

Binning it is probably the optimum but I put a pair of 15 amp bridge rectifiers in mine to keep it going for a bit longer. The big bridge rectifiers are not so critical on heat sinks as the smaller ones  

The resistance mat speed control is really poor though, trains race downhill and stop when faced with an uphill slope the older H and M variable transformers are vastly superior.

My layout is dcc, but I have recently purchased a DMU not fitted with dcc and want to run it on dc to start with, although I don't want to have to purchase another dc controller, if I can get my H&M to work. Neverthless, I cannot recognise the rectifiers, so can you tell me where they are and exactly how to install replacements. I add a photo of the interior of the appliance.

[cliff park]

Old style plate rectifiers

[DCB]

If you don't know what a rectifier looks like I would suggest you bin the Duette right now.

 

Mine has "square" rectifiers with + and - diagonally opposite with the AC on the other corners  (see photo, Ebay £1.99 free postage) wired much like the diagram  I drew from memory.

 

It is asymmetric as one side has an uncontrolled AC outlet and the other a DC outlet so one connected after the cut out and other after the  rectifier.

 

 Obviously if you have a go at fixing it you could save a few bob or you could burn the house down, or the whole street if you live in a terrace.  Or you could electrocute yourself and die and the wife go off to the Carribean with the bloke from the drama group to spend the life insurance money.

[newbryford]

If you don't know what a rectifier looks like I would suggest you bin the Duette right now.

 

Mine has "square" rectifiers with + and - diagonally opposite with the AC on the other corners  (see photo, Ebay £1.99 free postage) wired much like the diagram  I drew from memory.

 

It is asymmetric as one side has an uncontrolled AC outlet and the other a DC outlet so one connected after the cut out and other after the  rectifier.

 

 Obviously if you have a go at fixing it you could save a few bob or you could burn the house down, or the whole street if you live in a terrace.  Or you could electrocute yourself and die and the wife go off to the Carribean with the bloke from the drama group to spend the life insurance money.

 

There is the issue of the "half-wave" switch that Duettes (and other H&M) controllers have, complicating it a bit more.

 

I would go with the "don't burn your house down" recommendation.

 

IIRC, H&M controllers are riveted together and there looks to be a self-tapping screw along the case lower edge.............. So either you've drilled the rivets out, or someone previous has.

 

Cheers,

Mick

[PatB]

There is the issue of the "half-wave" switch that Duettes (and other H&M) controllers have, complicating it a bit more.

 

I would go with the "don't burn your house down" recommendation.

 

IIRC, H&M controllers are riveted together and there looks to be a self-tapping screw along the case lower edge.............. So either you've drilled the rivets out, or someone previous has.

 

Cheers,

Mick

Dad and I had an old Duette (which he probably bought c1968 but which may have been 2nd hand even then) which appeared to have been held together with self-tappers from the factory. They may have gone to all-riveted construction as progressively less trust was put in the public to not do anything silly with mains electricity.

[Gordon H]

If you don't know what a rectifier looks like I would suggest you bin the Duette right now.

 

Mine has "square" rectifiers with + and - diagonally opposite with the AC on the other corners  (see photo, Ebay £1.99 free postage) wired much like the diagram  I drew from memory.

 

 

The originals are selenium bridge rectifiers, which presumably were the most cost effective option at the time.

Apparently they are still made, but I've never come across any in the usual vendors ranges. Hardly surprising that someone new to the subject might not recognise them.

See here: https://en.wikipedia.org/wiki/Selenium_rectifier

[johnb]

Dad and I had an old Duette (which he probably bought c1968 but which may have been 2nd hand even then) which appeared to have been held together with self-tappers from the factory. They may have gone to all-riveted construction as progressively less trust was put in the public to not do anything silly with mains electricity.

The early H&M controllers were screwed together when made, It was not long though before they were rivetted. Safety and all that!

 

I would strongly suggest that you scrap the one under discussion, it has to be 30+ years old. There is full mains voltage in there and the insulation must have deteroriated by now, disturbing things will only raise the risk of insulation failure a lot.

 

IMHO it's just not worth the risks to try to salvage it.

 

A Hornby DC setup with a 'wall wart' transfomer and a small controller is not too expensive.

 

John

[kevinlms]

Dad and I had an old Duette (which he probably bought c1968 but which may have been 2nd hand even then) which appeared to have been held together with self-tappers from the factory. They may have gone to all-riveted construction as progressively less trust was put in the public to not do anything silly with mains electricity.

Maybe as a RESULT of people doing silly things with mains electricity!

 

This page suggests that the number of deaths by electrical means, rose from 1950 to 1973 (38 to 70) and then down to 3 by 2013.

 

http://www.theiet.org/forums/forum/messageview.cfm?catid=205&threadid=61494

 

So something clearly changed! There were new standards around then (early 70s), so using rivets, rather than self tappers, would appear to be just one step towards better safety.

[hayfield]

The early H&M controllers were screwed together when made, It was not long though before they were rivetted. Safety and all that!

 

I would strongly suggest that you scrap the one under discussion, it has to be 30+ years old. There is full mains voltage in there and the insulation must have deteroriated by now, disturbing things will only raise the risk of insulation failure a lot.

 

IMHO it's just not worth the risks to try to salvage it.

 

A Hornby DC setup with a 'wall wart' transfomer and a small controller is not too expensive.

 

John

 

 

Might it be cheaper buying a s/h one from a local model railway show, they seem to be quite common

[kevinlms]

Might it be cheaper buying a s/h one from a local model railway show, they seem to be quite common

Or it could have exactly the same problem!

 

Before selling them, the seller ought to get them tested & tagged, or else provide a label stating that it hasn't been tested & its the purchasers obligation to get it checked, before use.

[Titan]

The originals are selenium bridge rectifiers, which presumably were the most cost effective option at the time.

Apparently they are still made, but I've never come across any in the usual vendors ranges. Hardly surprising that someone new to the subject might not recognise them.

See here: https://en.wikipedia.org/wiki/Selenium_rectifier

 

Not only that, but they have an extra terminal for the half wave function, so look even less like a conventional rectifier. I have replaced duff rectifiers on mine with the modern square four terminal type, but it does mean that I have to do without the half wave function. I suppose that I could use individual diodes such that I could get the half wave facility back again, but I did not use it much anyway. 

[newbryford]

Might it be cheaper buying a s/h one from a local model railway show, they seem to be quite common

 

Bearing in mind that the OP is in Spain.....

 

Cheers,

Mick

[hayfield]

Bearing in mind that the OP is in Spain.....

 

Cheers,

Mick

 

 

Missed that bit, as for the s/h one all electrical items for sale should be tested and tagged appropriatly

[petertg]

Thanks for all the comments. I shall bear them in mind before making any moves.

 

The self tapping screw is due to having opened the appliance some time back to repair a different fault. The appliance has been mine since new.

[Pete the Elaner]

I fail to understand why people seem to be so fond of regenerating these old things. They provide poor control between stop & half speed & things like this do not go on forever.

Modern electronic controllers give far better performance even with old Hornby Dublo locos. They don't cost a fortune either, easily justifying their purchase price.

[hayfield]

I fail to understand why people seem to be so fond of regenerating these old things. They provide poor control between stop & half speed & things like this do not go on forever.

Modern electronic controllers give far better performance even with old Hornby Dublo locos. They don't cost a fortune either, easily justifying their purchase price.

 

 

Pete

 

I have a Duet which I constantly use for testing things I build, I agree that for running a layout either one of the more modern DC controllers or a DCC system is better, also I guess these are also better for the older vintage locos of their era or earlier 

[CloggyDog]

If you just want something to test a DC item, why not just make a simple and cheap battery controller??

 

DSC_0450 by Alan Monk, on Flickr

 

6 x AA battery holder, a PWM board, a DPDT switch and a few offcuts of wire, all in a suitable plastic box (the 0.2l Really Useful Box is spot-on). Just add batteries (rechargables, ideally) and you're good to go, even away from a mains supply. Cost of components (less batteries) is around £5 (or 6 Euros).

 

Gives around 8v dc at rail, with better control than the Duette.

 

(Pic shows v1.0, with 4 x AA and a large DPDT switch, since swapped out for 6 x AA and a more compact switch)

[griffgriff]

If you just want something to test a DC item, why not just make a simple and cheap battery controller??

 

DSC_0450 by Alan Monk, on Flickr

 

6 x AA battery holder, a PWM board, a DPDT switch and a few offcuts of wire, all in a suitable plastic box (the 0.2l Really Useful Box is spot-on). Just add batteries (rechargables, ideally) and you're good to go, even away from a mains supply. Cost of components (less batteries) is around £5 (or 6 Euros).

 

Gives around 8v dc at rail, with better control than the Duette.

 

(Pic shows v1.0, with 4 x AA and a large DPDT switch, since swapped out for 6 x AA and a more compact switch)

It's the pure DC you get from battery cells that gives smooth, dare I say stutter (hum) free, running. It's a set up well worth considering for small layouts well as test tracks.

 

Griff

[petertg]

I do not want the dc controller for regular use. I only want to test out my most recent (non-dcc) purchase and, possibly, any future purchases. My local dealer has a dc controller for €60 or a start set with locomotive 2 trucks and a transformer for €100, but I don't want to spend that sort of cash for what might well be a one-off job. I'll show all these comments to my son-in-law, who is the handyman of the family, and see what we can do.

I really appreciate the interest shown.

[BR60103]

A 9V battery will give a start to the testing. The contacts ride nicely on 00 rails. No subtle control, though.

[tractor_37260]

My layout is dcc, but I have recently purchased a DMU not fitted with dcc and want to run it on dc to start with, although I don't want to have to purchase another dc controller, if I can get my H&M to work. Neverthless, I cannot recognise the rectifiers, so can you tell me where they are and exactly how to install replacements. I add a photo of the interior of the appliance.

H&M Controller.JPG

 

 

    You might just be in luck, I may have 1 or perhaps more of these rectifiers (unused), still in their original HM boxes. They were available as spares a long time back !  I'll have a look over the weekend and get back to you

 

EDIT: Found this - not HM (only have cut out/reset button replacements for the Major). It's very similar to the HM rectifiers, I've got 1 x 3Amp one.  The HM Duette outputs, from memory I think were 2 x 1.5 Amps, so this would get one output working.

 

Let me know if it's of use to you

 

Regards

Ken