Evan-380262 Posted February 1 Share Posted February 1 Hi,I have a question concerning fusing for an old 12V transformer 'Hornby Dublo Type 00/1'.I recently received the transformer which passes all safety tests, but it's obviously fitted with incorrect fuses. I don't have user instructions.Please could you advise the correct fuse physical size / rating for this product?Kind regards,Evan Link to comment Share on other sites More sharing options...
P-Henny Posted February 1 Share Posted February 1 Please could you advise the correct fuse physical size / rating for this product? The phrasing of this part of your post suggests to me that you believe Hornby staff will be reading your post and responding to it.Be aware that this forum is ALL user generated content. So any answers your post generates will be posted by forum members who may either use the specified product or have experience of it.The label (see link below) says "Fuses" are under the terminals. The plural "fuses" suggests that there is both an input and an output fuse. Or both legs of the output have an individual fuse, which seems to me to be very unusual.The label on the product states that the output is rated 12 volts AC @ 1 Amp. Therefore any output fuse should not be greater than 1 Amp.For an output current of 1 Amp @ 12 VAC, the input current will be significantly less than 100 mA (0.1 Amps).https://tri-angman.co.uk/product/meccano-hornby-dublo-00-1-transformer-in-excellent-tested-condition/EDIT: I agree with GS below. The age of this product means that I personally wouldn't touch it with a 'barge pole' even if it has been tested. 12 volt AC Transformers can be sourced with higher than 1 Amp currents and more importantly constructed to modern safety standards. Link to comment Share on other sites More sharing options...
Going Spare Posted February 1 Share Posted February 1 Frankly, because of its age (early post-war?), I would be loathe to use it.However, if it and its mains cable have been fully checked by an electrician, I would use nothing higher than a 3 amp fuse in the plug.The unit appears to have a 1 amp output rating so others will be more qualified to say whether an even lower-rated fuse might be appropriate. Link to comment Share on other sites More sharing options...
What About The Bee Posted February 1 Share Posted February 1 My understanding of these instructions is as follows.The fuses are on the output side of the transformer. You could, of course, confirm this with a volt-ohm meter. The electrical plate of the transformer indicates the output at 1 amp at 12 volts. Conservatively, then, select 0.9 amp @ 12 VDC. Feeling bold? 1 amp @ 12VDC. In other words, the fuse should match the rating or slightly less.Bee Link to comment Share on other sites More sharing options...
LTSR_NSE Posted February 1 Share Posted February 1 I would be most interested to hear how the product has passed proper safety tests by an electrician with incorrect fuses present?Unless replaced with correct ones before test (or testing redone after replacement) a ‘proper’ test would fail a device with incorrect fuses as hazardous! Link to comment Share on other sites More sharing options...
Going Spare Posted February 1 Share Posted February 1 Thank you, Bee, for finding these instructions. It is the first time I have encountered fuses on the output side of a transformer; once again, proves you are never too old to learn! Link to comment Share on other sites More sharing options...
P-Henny Posted February 1 Share Posted February 1 Plus fuses on both output legs seems exceptionally strange. But I suppose when this product was made, there were less standard construction methods.Also, the imagery gives no clue as to how one gets access to the fuse locations under the terminals. Link to comment Share on other sites More sharing options...
Rana Temporia Posted February 1 Share Posted February 1 Unless it’s been rewired I would worry about perished rubber wire coverings and asbestos insulation. Link to comment Share on other sites More sharing options...
What About The Bee Posted February 1 Share Posted February 1 LT&SR_NSE You do a visual check on the mains chord, inspecting for insulation integrity. Check for leakage path from mains to case, mains to any exposed metals, etc. None of this requires the unit to be plugged in or power applied.Checking for functionality is different from checking for safety. Checking for functionality means you know what the device is to do. Hand me an 80 year old device and I may balk.Going SpareI expect that the transformer was protected from the mains by a fuse in the house circuit. The fuses on the output legs are to protect the controller and the motor in the locomotive. Thus 1 amp @12vdc.I thought I got super lucky as I found a catalog. And there is was. Fuses. Absolutely no specification! There is also a specific transformer instruction sheet which I had no luck locating.Bee Link to comment Share on other sites More sharing options...
What About The Bee Posted February 1 Share Posted February 1 Golly. On re-reading this for possibly the 1000th time, it occurs to me that the fuses may be on the 250V side, to "protect the Transformer".The only way to be sure is to carefully probe the unit under power. Pull whatever fuses are in the unit out. Apply voltage. And test. I take no responsibility for the actions of anyone in regards to this unit. Probing a unit under power is not for the unwary or uneducated. It can result in injury or death. 10 amps @250VAC can be lethal. Personally, unless I was super determined to use this old kit, I would merely display it boldly on the layout, wired up for purpose. And never turn it onA modern controller, discretely hidden, would drive my locomotives 'round.Bee Link to comment Share on other sites More sharing options...
Going Spare Posted February 1 Share Posted February 1 Bee: I think your first interpretation was correct. The type of fuse used will be interesting to discover.Evan: No-one at Hornby will have any information to answer your question, Hornby-Dublo (Meccano Ltd.) having been a totally separate entity to the present Hornby. The Hornby Railways Collectors Association may be able to help but taking out membership may be required. Link to comment Share on other sites More sharing options...
What About The Bee Posted February 2 Share Posted February 2 Behold the grail. A box of 1 amp fuses for the Hornby Dublo No. 1 Transformer.Bee Link to comment Share on other sites More sharing options...
What About The Bee Posted February 2 Share Posted February 2 While I wait for the image to be approved, the Hornby Dublo Transformer No. 1 FUSE is product number BSS646.I note there is a commercially available fuse BS646 at 1 amp. That is one heck of a coincidence.Bee Link to comment Share on other sites More sharing options...
threelink Posted February 2 Share Posted February 2 Having dismantled a few older transformer/controllers in my time I would advise in the strongest possible terms that this item is not used. Age does funny things to insulation. The last transformer I took to pieces was an electrocution waiting to happen. Link to comment Share on other sites More sharing options...
96RAF Posted February 2 Share Posted February 2 Having dismantled a few older transformer/controllers in my time I would advise in the strongest possible terms that this item is not used. Age does funny things to insulation. The last transformer I took to pieces was an electrocution waiting to happen. OP does say it has passed all safety tests, thus presumably carried out and certified by a qualified sparky. @BeeBS646 is a British Standard predating European (EN) standards.Normally the additional S would refer to a slo-blow fuse. Link to comment Share on other sites More sharing options...
Evan-380262 Posted February 2 Author Share Posted February 2 Thank you all for your useful comments and suggestions. I hadn't realised the question would generate that much response.The two fuses in question were on the transformer secondary, and those fitted were of different sizes and ratings to each other. I have enough info now to get it sorted, thank you.Incidentally, the safety testing wasn't affected by incorrect secondary fuses. The transformer was treated as a Class II appliance and passed all visual checks and dialectric tests.Thanks once again, Evan Link to comment Share on other sites More sharing options...
LTSR_NSE Posted February 2 Share Posted February 2 LT&SR_NSEYou do a visual check on the mains chord, inspecting for insulation integrity. Check for leakage path from mains to case, mains to any exposed metals, etc. None of this requires the unit to be plugged in or power applied… Fair enough Bee, I was referring to a PAT test (a specific type of safety test - my error for not stating that) rather than a simple visual check. Link to comment Share on other sites More sharing options...
What About The Bee Posted February 2 Share Posted February 2 Hello EvanI do hope it is sorted. When you have a final result, would you mind updating us? You will not be the last person with this problem. Looking out for the next modeler to come along, your update will be useful.Bee Link to comment Share on other sites More sharing options...
LTSR_NSE Posted February 2 Share Posted February 2 Incidentally, the safety testing wasn't affected by incorrect secondary fuses. The transformer was treated as a Class II appliance and passed all visual checks and dialectric tests. Thanks Evan, most interesting. Having been required to have 1000s of items PAT tested over several years, I’ve experienced failures for: damaged cases, damaged cables, incorrect fuses, switched live & neutral wires, damaged/degraded insulation etc…The highlight always (for me) were the occasions when the electrician plugged his tester into a wall socket (to test equipment) & it immediately reported that the socket had been mis-wired (live & neutral switched). I’m not so sure that he found it that enjoyable having to then check & re-wire a roomful of sockets! 🤭 Link to comment Share on other sites More sharing options...
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