Freypal Posted January 11, 2020 Share Posted January 11, 2020 Hi, quick question hopefully.I was looking at picking up a 28xx model (2847 is one I'd looked at) and noticed it has a smoke unit and glowing firebox as standard. I'd like to keep the glowing firebox but would like to disconnect the smoke unit, ideally without damaging anything. Looking at service sheet 277b-248 it looks like the smoke unit just plugs into the glowing firebox and works in a parallel circuit. As such is it simply a case of taking the loco body off and unplugging the two wires to disconnect it? I'm hoping doing so wouldn't affect the glowing firebox or pickups? Thanks Link to comment Share on other sites More sharing options...
Mico11 Posted January 11, 2020 Share Posted January 11, 2020 Hello Freypal, and welcome.On this page and in the "Search Forums" column you may care to type in 28XX to find previous discussion on this subject. Link to comment Share on other sites More sharing options...
Freypal Posted January 11, 2020 Author Share Posted January 11, 2020 Hi, thanks. I'd had a search and found some topics on how to access the unit for maintenance / replacement and also on maintaining the functionality with DCC but nothing on leaving it in-situ and just disconnecting it. Just had another look and couldn't see anything on the specific query. Thanks Link to comment Share on other sites More sharing options...
walkingthedog Posted January 11, 2020 Share Posted January 11, 2020 Looking at the service sheet it looks as if the smoke unit is plugged in in parallel with the glow box and you should be able to unplug it. If it doesn't unplug I suggest you cut the wires to the smoke box but not too near the glow box or smoke unit in case you need to rejoin the wires. Insulate the ends of the live wires once cut. Link to comment Share on other sites More sharing options...
DBfan Posted January 11, 2020 Share Posted January 11, 2020 Be very careful fitting the smole unit, it can lead to the smokebox sagging. It is best left out Link to comment Share on other sites More sharing options...
Ruffnut Thorston Posted January 11, 2020 Share Posted January 11, 2020 Thing is... The OP has a loco with the smoke unit already fitted. They want to isolate it to avoid any problems... So it will need two wires isolating. All the Tender Drive GWR 2800 class 2-8-0 Locomotives seem to have been fitted with the Hornby Railways Plastic Smoke Unit. Originally introduced in 1981, it was eventually phased out except for the 2800 locos...which also have a 'glowing firebox' feature... The newer tool 2800, doesn't have either feature, and is loco drive. Link to comment Share on other sites More sharing options...
ColinB Posted January 12, 2020 Share Posted January 12, 2020 In answer to your original question, if it is like my 1980's locos with smoke, the smoke unit is on two flying leads which terminate in spade connectors. Just pull them off. The smoke unit on mine is held in with a little screw, and is inside a tube underneath the chimney, unscrew the screw and it should pull out. Watching them smoke is really good but it is very messy, also if the tin foil around the smoke unit gets removed you will find your body will distort with the heat, mine did. I could say replace the lamp that does the smoke box glow, with a led and resistor, but if you are using DC it would only work in one direction. Link to comment Share on other sites More sharing options...
Freypal Posted January 12, 2020 Author Share Posted January 12, 2020 Perfect, thanks for the replies all. So it should be simple to do. It would be nice to have the option of using it occasionally so a non-permanent disconnection is ideal. @ColinB what was the reason for saying replace the lamp with an LED? Im assuming as it looks like the smoke unit is wired in parallel, disconnecting it shouldn't have an effect on the glowing firebox? Thanks Link to comment Share on other sites More sharing options...
ColinB Posted January 13, 2020 Share Posted January 13, 2020 No, don't bother replacing the bulb with a LED. It is only if it fails and you can't get a flickering bulb, you can buy flinkering LEDs. If you ever go to DCC you might have to replace the bulb with a LED as the bulb probably consumes too much power but for DC keep it as it is. With DC to replace the bulb with a LED you would need to use a bridge rectifier, so don't bother. Link to comment Share on other sites More sharing options...
Chrissaf Posted January 13, 2020 Share Posted January 13, 2020 With DC to replace the bulb with a LED you would need to use a bridge rectifier,.And a resistor to limit the current. Link to comment Share on other sites More sharing options...
Ruffnut Thorston Posted January 13, 2020 Share Posted January 13, 2020 I converted an old Margate Tender Drive 2800 to DCC. I had an LED, with resistor, connected to the 8 pin socket that I installed, so that it worked in both directions, wired to what would, on a diesel, be both directional head and tail lights. The decoder had a setting to make the LED flicker... Thing is, that when I took the decoder out, and put a standard blanking plug in place, there was a direct short caused by that connexion. So, I have re wired the LED to just the 'headlight' function, so no short with a blanking plug, but it now only works in the one direction. I could put a second LED and resistor in place wired to the "tail lights" function... I may even get around to this... Taking the smoke unit out of circuit does not affect the lighting. That's a completely separate circuit. Link to comment Share on other sites More sharing options...
Freypal Posted January 13, 2020 Author Share Posted January 13, 2020 Lovely, thanks for all the info everyone, exactly what I needed! Understand with regards the LEDs too. I have an '80s 8F from from my childhood with a glowing firebox and l always loved it so good to know I can retain it. Link to comment Share on other sites More sharing options...
Chrissaf Posted January 13, 2020 Share Posted January 13, 2020 Sarah,I take it that the decoder in question didn't have a green or purple function wire that you could have wired the firebox LED to....rather than the white and/or yellow directional lights wire Link to comment Share on other sites More sharing options...
Ruffnut Thorston Posted January 13, 2020 Share Posted January 13, 2020 Hi Chris. Yes, that may well have been the best option, as the decoder had the full set of wires. I was hoping to make it so that the firebox lighting would work on DC analogue as well. It did work ok. It was only when I took the decoder out and fitted a blanking plug, with a view to selling the loco, after we got hold of a newer tooled loco drive version, that I discovered that the joining of head and tail light wires causes a short circuit with the blanking plug in place. And that only after a bit of head scratching, as to why the sudden short! 😉 Link to comment Share on other sites More sharing options...
ColinB Posted January 14, 2020 Share Posted January 14, 2020 Yes, forgot about the resistor. Link to comment Share on other sites More sharing options...
Chrissaf Posted January 14, 2020 Share Posted January 14, 2020 Sarah,For future reference if you wire your Glowing Smoke Box like this, you can get the functionality you prefer as you described (DCC or DC) but without the short circuit when a blanking plug is fitted.../media/tinymce_upload/f44a42b8c4375ac3a47b38fd29ec4a9c.jpg.Diodes D1 & D2 pass the negative voltage to light the LED subject to which DC Analogue direction is in use, but prevent a current flowing (thus no short circuit) between the wheel pickups when a blanking plug is fitted. They also pass the switched negative if a decoder is fitted, thus the D1 & D2 diodes are both DC & DCC friendly..The smaller diodes with the dotted lines need to be there to provide the positive supply. These diodes usually form part of the main lighting PCB in non steam locos. Sometimes they may be incorporated on the blanking plug itself for some locos. However with a steam loco where the lights are unlikely to be a factory option or a non 'DCC Ready' loco where the decoder is DIY installed 'hard wired' or with a DIY socket. Then the two smaller drawn diodes would need to be added as well to provide the positive return current path..The curved purple dotted lines represent the pin connections that a basic 'blanking plug' would provide..Suitable diodes would be any of the 1N4000 series. Link to comment Share on other sites More sharing options...
Ruffnut Thorston Posted January 14, 2020 Share Posted January 14, 2020 Thanks for that Chris.. Very informative... 😀 Link to comment Share on other sites More sharing options...
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