hoovernut Posted May 17, 2015 Share Posted May 17, 2015 Evening all. I have just had a pal send me the attached pic with a strange query. The chip came out what he thought to believe a 21 chassis but he has found out that it is an 8 pin one.The stange thing is the cab lights come on when its in motion. Up until know the only way the light would have been on would of been it had of on a 21 pin chassis. looking at the blanking chip it looks to small to be a decoder plus it looks unlikly to be a standard blanking chip. one other thing to add unlike a standard blanking chip it has seven pins and not six. Any idear. Thanks in advance Kingy Link to post Share on other sites More sharing options...
shibushe Posted May 17, 2015 Share Posted May 17, 2015 Had a look in my blanking plug box, I have21 & 8 Pin. 6 Pin. & 4 Pin. I think the 4 & 6 Pin are so wired to run motor only. Not sure if the 8 Pin is all pins wired. With an 8 Pin decoder you can operate lights, its not limited to 21 Pin. In answer to your question, It may be just one of those mysteries. Link to post Share on other sites More sharing options...
tractor_37260 Posted May 17, 2015 Share Posted May 17, 2015 Evening all. I have just had a pal send me the attached pic with a strange query. The chip came out what he thought to believe a 21 chassis but he has found out that it is an 8 pin one.The stange thing is the cab lights come on when its in motion. Up until know the only way the light would have been on would of been it had of on a 21 pin chassis. looking at the blanking chip it looks to small to be a decoder plus it looks unlikly to be a standard blanking chip. one other thing to add unlike a standard blanking chip it has seven pins and not six. Any idear. Thanks in advance Kingy There's 2 different versions of 21pin blanking plugs, with one the cab lights will work type (B), but not with the other type (A) also note the solder blob joining pads at J2 on B - the 2 small black boxes are diodes. 8pin locos have 8 pins on the plug ! - unlikely 7 ? unless one has been broken ? although it's the first 8pin blanking plug I've seen with diodes ? HTH Ken Link to post Share on other sites More sharing options...
hoovernut Posted May 17, 2015 Author Share Posted May 17, 2015 Had a look in my blanking plug box, I have21 & 8 Pin. 6 Pin. & 4 Pin. I think the 4 & 6 Pin are so wired to run motor only. Not sure if the 8 Pin is all pins wired. With an 8 Pin decoder you can operate lights, its not limited to 21 Pin. In answer to your question, It may be just one of those mysteries. Very much a mystery , i dont get it. There's 2 different versions of 21pin blanking plugs, with one the cab lights will work type (B), but not with the other type (A) also note the solder blob joining pads at J2 on B - the 2 small black boxes are capacitors. 8pin locos have 8 pins on the plug ! - unlikely 7 ? unless one has been broken ? although it's the first 8pin blanking plug I've seen with capacitors ? HTH Ken That makes two of us ref the capacitors Ken, im not sure if it is something thats been done on purpose. Link to post Share on other sites More sharing options...
tractor_37260 Posted May 17, 2015 Share Posted May 17, 2015 Very much a mystery , i dont get it. That makes two of us ref the capacitors Ken, im not sure if it is something thats been done on purpose. Diodes NOT capacitors ! corrected my original post Link to post Share on other sites More sharing options...
RMweb Gold Huw Griffiths Posted May 17, 2015 RMweb Gold Share Posted May 17, 2015 I'd imagine the diodes might have something to do with lighting - perhaps something like keeping pin 7 positive compared to at least one of the power input connections, to allow lights to go on. Saying that, I am only guessing. Link to post Share on other sites More sharing options...
Sir Topham Hatt Posted May 18, 2015 Share Posted May 18, 2015 Yep, looks that way. It's odd to see a custom 8 pin blanking plug used like that but if it works for DC then it's a neat and simple lighting solution. The fitting of a decoder will probably resolve the cab light problem which will operate under a different function button but for DC, not sure. Try the manufacturer for advice? Cut the cab bulb connection! Link to post Share on other sites More sharing options...
Adrian Wintle Posted May 19, 2015 Share Posted May 19, 2015 Yep, looks that way. It's odd to see a custom 8 pin blanking plug used like that but if it works for DC then it's a neat and simple lighting solution. The fitting of a decoder will probably resolve the cab light problem which will operate under a different function button but for DC, not sure. Try the manufacturer for advice? Cut the cab bulb connection! The three soldered together connections at each end of that are each one pickup, one motor contact and one of the F0 contacts. The single pin is the common function return. The diodes are there to give directional lighting under DC. An 8-pin 2-function decoder uses 7 pins (Pickup+/-, Motor+/-, F0+, F0-, common), so the blanking plug is set up the same way. The 8th pin can optionally be used for F1. I think the issue with that is the blanking plug is in the wrong way around - the empty pin should be Pin 3, not Pin 7 as it is currently installed. This is probably why the cab lights are coming on. Table 2 here http://www.nmra.org/sites/default/files/standards/sandrp/pdf/S-9.1.1_Connectors_2013.07.pdf has the pin assignments for the 8-pin connector. Adrian Link to post Share on other sites More sharing options...
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