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H & M Clipper help required

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22 hours ago, Bernard Lamb said:

What is the expert opinion about using an ancient Powermaster. I use one to power an oval of set track in my work room and use it to test stock. I usually run a small diesel loco round to check bearings, couplings, corridor connectors and such like. Should I ditch it and replace it with a modern transformer and plug in one of my Gaugemaster Ws?

Bernard

 

Hi Bernard,

 

There were several versions of the H&M Powermaster. The earlier versions most likely used selenium rectifiers. It's not impossible that the later versions employed silicon rectifiers but I really don't know.

 

Even if it has selenium rectifiers and you are only using it very occasionally the risk of the rectifiers going south and causing injury is very small. The more important thing is that you are aware that there could possibly be a problem and you vacate the area at the slightest sign of trouble. And, as others have correctly pointed out there are potential issues with old electrical equipment quite apart from the rectifiers.

 

If you prefer to minimize all risks it's probably best to dump it.

 

Andy

 

 

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13 minutes ago, Hroth said:

 

p.s. How far did the flames go?

 

 

About three feet. I was sufficiently shocked to never repeated the experiment.

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3 minutes ago, AndyID said:

 

Hi Bernard,

 

There were several versions of the H&M Powermaster. The earlier versions most likely used selenium rectifiers. It's not impossible that the later versions employed silicon rectifiers but I really don't know.

 

Even if it has selenium rectifiers and you are only using it very occasionally the risk of the rectifiers going south and causing injury is very small. The more important thing is that you are aware that there could possibly be a problem and you vacate the area at the slightest sign of trouble. And, as others have correctly pointed out there are potential issues with old electrical equipment quite apart from the rectifiers.

 

If you prefer to minimize all risks it's probably best to dump it.

 

Andy

 

 

Wise advice. As a Hornby-Dublo fan I have several old examples of Meccano electrics, I haven’t put power into them since the 1980s. Failing insulation inside the case can’t be seen etc. Retained solely due to collectable interest, not for practical use.

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Thing is, according to my limited understanding of these things, where Clippers and Duettes are concerned, the rectifier is on the "low voltage" side of the transformer, so if it gives up, there will either be no voltage to the controller at all or a bastard low voltage (circa 15v) AC supply. So a loco will either just halt or stop and hum itself to death.

 

I'd be more concerned with the transformer windings shorting out due to failure of the varnish coating the wires, but provided the fuse in the plug is low enough (3A) that should let go and protect all and sundry.

 

 

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10 minutes ago, AndyID said:

 

Hi Bernard,

 

There were several versions of the H&M Powermaster. The earlier versions most likely used selenium rectifiers. It's not impossible that the later versions employed silicon rectifiers but I really don't know.

 

Even if it has selenium rectifiers and you are only using it very occasionally the risk of the rectifiers going south and causing injury is very small. The more important thing is that you are aware that there could possibly be a problem and you vacate the area at the slightest sign of trouble. And, as others have correctly pointed out there are potential issues with old electrical equipment quite apart from the rectifiers.

 

If you prefer to minimize all risks it's probably best to dump it.

 

Andy

 

 

Thanks Andy.

It is probably time to get rid of it.

I must have bought it soon after they were introduced.

It was replaced free of charge many years later, so I have no idea of an actual date of manufacture.

A couple of the section switches no longer work so it is no use for a layout even if it is considered as safe to use.

I would reckon that I have had more than value for money out of it. Several times over probably.

Bernard

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25 minutes ago, Hroth said:

 I've a Clipper and a Duette that are suffering from worn resistance mats and was toying with the idea of opening them up and trying to do something about them. Having seen the innards of the Clipper posted above, I've decided that the best option would be to drill out the rivets, discard the internals and use the cases to contain new electronic gubbins.  That seems the safest option!

 

I'd be inclined to keep the transformers too, but that's just me (and mains voltage in the US is four times less lethal than it is in the UK). If you are not sure, dump the lot and re-use the nice cases.

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5 minutes ago, Hroth said:

I'd be more concerned with the transformer windings shorting out due to failure of the varnish coating the wires, but provided the fuse in the plug is low enough (3A) that should let go and protect all and sundry.

 

Unfortunately, in the event of insulation breakdown between the primary and secondary transformer windings the fuse will not protect anyone from potential electrocution but it will help to prevent a fire. A GFI (ground fault interrupter) (called something else in the UK) will protect against electrocution. They can be a bit of a nuisance if they trip too often but they really do save lives.

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1 minute ago, AndyID said:

Unfortunately, in the event of insulation breakdown between the primary and secondary transformer windings the fuse will not protect anyone from potential electrocution but it will help to prevent a fire.

 

The transformer in the Clipper in the photograph above has the primary and secondary windings formed on separate heavy plastic bobbins so the only link between the two is the magnetic flux carried by the laminated core. If the primary circuit shorts out there is little chance that the mains voltage will pass through to the low voltage side, mains fuse goes, jobs a goodun!

 

To be honest, the H&M looks well engineered internally, even if it appears crude to modern eyes.  I've got a couple of even older Hornby Dublo and Triang controllers that I don't even dare to plug in to use with their contemporary models due to the rubber insulated mains cables, let alone the state of their transformers!

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I've got both a clipper, and a duette, in fact these are the only things I use to electrify track...they seem to work fine for my purposes, I like the heavy duty old school-ness of them, and they haven't gassed or electrocuted me as yet...;)

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1 hour ago, AndyID said:

A GFI (ground fault interrupter) (called something else in the UK) will protect against electrocution.

In the UK they're called a Residual Current Device (RCD).

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On 15/09/2019 at 15:14, AndyID said:

 

That's nuthin. I put meths in my Mamod's boiler and converted it into a flame thrower. (DO NOT EVEN THINK ABOUT TRYING THIS AT HOME!)

 

(Apologies for the drift.)

Well, I hadn't thought about trying it before, but you can bet I am now :D

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