AndyID Posted September 15, 2019 Share Posted September 15, 2019 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 1 Link to post Share on other sites More sharing options...
AndyID Posted September 15, 2019 Share Posted September 15, 2019 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. 1 Link to post Share on other sites More sharing options...
RMweb Gold john new Posted September 15, 2019 RMweb Gold Share Posted September 15, 2019 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. 3 Link to post Share on other sites More sharing options...
Hroth Posted September 15, 2019 Share Posted September 15, 2019 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. Link to post Share on other sites More sharing options...
Bernard Lamb Posted September 15, 2019 Share Posted September 15, 2019 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 Link to post Share on other sites More sharing options...
AndyID Posted September 15, 2019 Share Posted September 15, 2019 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. Link to post Share on other sites More sharing options...
AndyID Posted September 15, 2019 Share Posted September 15, 2019 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. Link to post Share on other sites More sharing options...
Hroth Posted September 15, 2019 Share Posted September 15, 2019 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! Link to post Share on other sites More sharing options...
Porkscratching Posted September 15, 2019 Share Posted September 15, 2019 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... 1 Link to post Share on other sites More sharing options...
Hroth Posted September 15, 2019 Share Posted September 15, 2019 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). 2 1 Link to post Share on other sites More sharing options...
PatB Posted September 16, 2019 Share Posted September 16, 2019 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 . 3 Link to post Share on other sites More sharing options...
DCB Posted September 19, 2019 Share Posted September 19, 2019 The old rubber insulation gets a bad name but in my experience its the 1970s plastic insulation which deteriorates. Quite often it fractures where the cable twists and can expose both live and neutral wires. Those same 1970s transformers have pop rivets holding the bottom on instead of screws so you can't have a look see without it being obvious you have tampered with it. What the old controllers do have is decent overload protection so maybe keep the cut out and bin the rest. Link to post Share on other sites More sharing options...
Junctionmad Posted September 19, 2019 Share Posted September 19, 2019 (edited) On 15/09/2019 at 09:54, Porkscratching said: 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... I still have my original duette from 1969 . But frankly it’s not a good controller compared to even the most trivial of modern controllers . It’s just a resistance mat, ie a high powered pot. It’s not good from an electrical / electronic perspective ( nor would they pass modern legislation requirements ) I keep mine for sentimental value , so should you. Edited September 19, 2019 by Junctionmad Link to post Share on other sites More sharing options...
DCB Posted September 19, 2019 Share Posted September 19, 2019 (edited) On 15/09/2019 at 08:58, Hroth said: 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. My Duette had rectifier failure when it was a couple of years old in the 1970s and would only provide 1/2 wave on the bad side no matter which way the half wave switch was set. Subsequently a new rectifier cured it. On 15/09/2019 at 10:47, Hroth said: In the UK they're called a Residual Current Device (RCD). Everyone calls them RCDs "Arsie Dee" Few realise they are residual current devices and fewer understand what a residual current device is. Can't stress enough how important the correct rating fuse in the plug is, A friend's transformer caught fire as it was in an unventilated plastic box with a wooden base and was left on for ages, luckily we smelled it before any real harm was done. The 13amp fuse didn't exactly help... How often does one blow a 2 amp and the only one available is a 13 amp so in it goes- sorted. Edited September 19, 2019 by DavidCBroad Link to post Share on other sites More sharing options...
RMweb Premium kevinlms Posted September 19, 2019 RMweb Premium Share Posted September 19, 2019 3 minutes ago, DavidCBroad said: Everyone calls them RCDs "Arsie Dee" Few realise they are residual current devices and fewer understand what a residual current device is. Those that have no idea, shouldn't be playing with mains voltage - full stop! 4 Link to post Share on other sites More sharing options...
Junctionmad Posted September 19, 2019 Share Posted September 19, 2019 Not sure why we are taking about RCBs in this thread , in fact most domestic installations are actually RCBOs 30mA RCDs are not necessarily protection for transformers or the wires leading to them, they are almost exclusively there to protect humans from electrocution , though arnt a whole lot of use if the transformer goes on fire etc. 2 Link to post Share on other sites More sharing options...
MarkC Posted September 19, 2019 Share Posted September 19, 2019 Very useful thread, this, having dodged assorted thrown toys & spat out dummies... I had an interesting conversation at a show recently with the operators of an old Hornby-Dublo 3-rail exhibit. At first glance, they were using original mains-fed HD controllers. I was assured that the internals had been changed, and were now safe. Having been thrown across the room by one of those HD controllers when I was nobbut a lad, I was relieved to hear that. They are potentially lethal due to age-related breakdown of both components and cables. Mark 1 Link to post Share on other sites More sharing options...
RMweb Premium rab Posted September 19, 2019 RMweb Premium Share Posted September 19, 2019 6 hours ago, DavidCBroad said: My Duette had rectifier failure when it was a couple of years old in the 1970s and would only provide 1/2 wave on the bad side no matter which way the half wave switch was set. Subsequently a new rectifier cured it. Everyone calls them RCDs "Arsie Dee" Few realise they are residual current devices and fewer understand what a residual current device is. Can't stress enough how important the correct rating fuse in the plug is, A friend's transformer caught fire as it was in an unventilated plastic box with a wooden base and was left on for ages, luckily we smelled it before any real harm was done. The 13amp fuse didn't exactly help... How often does one blow a 2 amp and the only one available is a 13 amp so in it goes- sorted. 13amp fuse, surely you mean a piece sawn out of a 6 in nail. 1 3 Link to post Share on other sites More sharing options...
Free At Last Posted September 19, 2019 Share Posted September 19, 2019 Plugtop fuses were often mended with the silver paper from a fag packet. 2 1 Link to post Share on other sites More sharing options...
Porkscratching Posted September 19, 2019 Share Posted September 19, 2019 (edited) 1 hour ago, Free At Last said: Plugtop fuses were often mended with the silver paper from a fag packet. I've 'done' fuses with a bit off a nail too.. Needless to say I also won't be taking the advice of the bloke earlier to not use my old H&M transformers, they work for my purposes ta! I've also got a c1969 Akai reel to reel tape machine, I still use that too.. Edited September 19, 2019 by Porkscratching 1 Link to post Share on other sites More sharing options...
AndyID Posted September 20, 2019 Share Posted September 20, 2019 11 hours ago, Junctionmad said: Not sure why we are taking about RCBs in this thread , in fact most domestic installations are actually RCBOs 30mA RCDs are not necessarily protection for transformers or the wires leading to them, they are almost exclusively there to protect humans from electrocution , though arnt a whole lot of use if the transformer goes on fire etc. RCD - Residual Current Device is pretty obscure terminology. They call them GFIs (Ground Fault Interrupter) here. Still a bit obscure but maybe a bit more meaningful. The "ground fault" means some current is going to ground (which it shouldn't) and it might be going through you. Generally that's not a good thing. I'll put in my usual "plug" about voltage. Mains voltage in the UK is twice what it is in the US. That doesn't just double the chance of fatal electrocution. It quadruples it. Link to post Share on other sites More sharing options...
RMweb Gold Oldddudders Posted September 20, 2019 RMweb Gold Share Posted September 20, 2019 17 minutes ago, AndyID said: RCD - Residual Current Device is pretty obscure terminology. They call them GFIs (Ground Fault Interrupter) here. Still a bit obscure but maybe a bit more meaningful. The "ground fault" means some current is going to ground (which it shouldn't) and it might be going through you. Generally that's not a good thing. I'll put in my usual "plug" about voltage. Mains voltage in the UK is twice what it is in the US. That doesn't just double the chance of fatal electrocution. It quadruples it. GFI sounds more like Earth Leakage Trip, which I think was the predecessor to RCD in the UK. 1 1 Link to post Share on other sites More sharing options...
PatB Posted September 20, 2019 Share Posted September 20, 2019 Probably time for one of these. An oldie but still quite funny. 2 1 11 Link to post Share on other sites More sharing options...
AndyID Posted September 20, 2019 Share Posted September 20, 2019 19 minutes ago, Oldddudders said: GFI sounds more like Earth Leakage Trip, which I think was the predecessor to RCD in the UK. That sounds like a much better description. That's what these things do. The "Residual" bit makes no sense to me. Currents don't just "hang around". Either they go, or they don't. Link to post Share on other sites More sharing options...
RLWP Posted September 20, 2019 Share Posted September 20, 2019 Isn't is because they sort of subtract current from one wire from current in another. The difference should be zero, if it isn't the residual from the sum triggers the switch 4 Link to post Share on other sites More sharing options...
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