Victor Meldrew Posted November 20, 2009 Share Posted November 20, 2009 Anyone any idea what is causing this? I recently put a decoder (Lenz Silver) in a Hornby 50018, but when the loco goes on the track the circuit breaker immediately sees a 'short'. Reversing the plug and the loco works (backwards obviously with no lights). Thinking the decoder may be at fault, I put in a ZTC 4007 with the same problems (shorting or going backwards). Both decoders are working OK, so what is wrong with the 50? Link to post Share on other sites More sharing options...
Brian Posted November 20, 2009 Share Posted November 20, 2009 Anyone any idea what is causing this? I recently put a decoder (Lenz Silver) in a Hornby 50018, but when the loco goes on the track the circuit breaker immediately sees a 'short'. Reversing the plug and the loco works (backwards obviously with no lights). Thinking the decoder may be at fault, I put in a ZTC 4007 with the same problems (shorting or going backwards). Both decoders are working OK, so what is wrong with the 50? Hi As two different decoders are causing the same problem, I would check.... When the 8 pin plug is pushed into the socket, ensure that the pins aren't protruding through the underside of the socket and one or more is touching the metal chassis. A piece of PVC insulating tape placed under the socket will help if this is the problem? The only other thing I can think of is the locos circuit board might be defective? Have you tried the loco on dc with the dc blanking plug fitted? Link to post Share on other sites More sharing options...
RMweb Gold Barry Ten Posted November 20, 2009 RMweb Gold Share Posted November 20, 2009 Hi As two different decoders are causing the same problem, I would check.... When the 8 pin plug is pushed into the socket, ensure that the pins aren't protruding through the underside of the socket and one or more is touching the metal chassis. A piece of PVC insulating tape placed under the socket will help if this is the problem? The only other thing I can think of is the locos circuit board might be defective? Have you tried the loco on dc with the dc blanking plug fitted? Is this one of the early 50s that had a fault in the circuit board installation? I seem to recall that replacement boards were available. Link to post Share on other sites More sharing options...
Grovenor Posted November 20, 2009 Share Posted November 20, 2009 Is this one of the early 50s that had a fault in the circuit board installation? I seem to recall that replacement boards were available. Very likely as the original boards would exhibit just this symptom and only your system cutting out prevents the decoder frying. The problem was that the Hornby board has a bridge rectifier to produce power for the lights. The negative of this rectifier was connected to the socket where the pin goes for the blue wire. So when you plug the decoder in the correct way round the blue wire which is the positive of the decoder rectifier is connected directly to the negative of the on board rectifier. Result short circuit through two diodes in series across the rails. Reversing the plug buts the positive (blue) pin in a spare position hence no short. Really you want to junk that whole Hornby board, its there to create constant lighting on DC and is completely unnecessary for DCC, but that then gives you another problem in that Hornby connected all the diode lighting with common negative when DCC needs common positive so you then have to modify all the lighting boards. If you don't want to go down that path ask Hornby for a replacement board. Regards Link to post Share on other sites More sharing options...
Adrian Wintle Posted November 20, 2009 Share Posted November 20, 2009 50018 (R2348) was one of original three 50 releases that had the defective circuit board. Talk to Hornby - they sent me a replacement board when I asked (a few years ago now). Adrian Link to post Share on other sites More sharing options...
Victor Meldrew Posted November 20, 2009 Author Share Posted November 20, 2009 Thanks for the responses guys, The loco is fine on DC and I checked for contact with the protruding pins, however when I had the continuity tester on the socket without the decoder in, there is continuity between the red and blue pins! This has confirmed the nagging doubt I had about a fault in the board. I also have a 50045 that looks to be the same. I'll get on to Hornby about it. Link to post Share on other sites More sharing options...
Road Stone Posted November 21, 2009 Share Posted November 21, 2009 Hornby were very goodwhen I contacted them on this problem. Sent me a new board AND decoder. Very nice. Board is easy to change and I found the Hornby decoder, which is still in the 50, gives very good performance. Especially slow running. Cheers, Jerry Link to post Share on other sites More sharing options...
orlando bridge Posted November 23, 2009 Share Posted November 23, 2009 I had the same problem with 50045 as per other comments. Nearly fried the chip but managed to try it reversed, just in time I suspect......and it works OK. Link to post Share on other sites More sharing options...
ebbwdent Posted November 23, 2009 Share Posted November 23, 2009 Hmm - my problem with 50045 is a little more strange. For some reason, it shorts the circuit out when going over one particular point. Other co-co locos are fine. Why the 50? Your thoughts please..... Link to post Share on other sites More sharing options...
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