Gingerman Posted September 2, 2013 Share Posted September 2, 2013 Good afternoon everyone I just installed a r8249 chip into a hornby schools class, as soon as I turn on my dynamis controller the loco moved. The controller speed dial was at zero and I just had no control. Took the chip out and tried the loco on dc with no problems, checked all wired and re installed the chip, the loco did the same thing but this time the chip went up in smoke. Now before I purchase another chip can anyone tell me what went wrong. Kind regards Link to comment Share on other sites More sharing options...
poliss Posted September 2, 2013 Share Posted September 2, 2013 It could be that the pins on the plug were projecting too far through the socket and causing a short circuit, or it could have just been a dodgy decoder. Link to comment Share on other sites More sharing options...
Gingerman Posted September 2, 2013 Author Share Posted September 2, 2013 Okay thanks for the reply poliss, will look at purchasing another decoder and trying again. Many thanks Link to comment Share on other sites More sharing options...
RDS Posted September 2, 2013 Share Posted September 2, 2013 @Gingerman If you bought the decoder from a Hornby dealer, I would take it all back, including your loco and ask for advice regarding what has happened because if it the plug in type you should just be able to plug it in without these sort of problems. Link to comment Share on other sites More sharing options...
Fishmanoz Posted September 2, 2013 Share Posted September 2, 2013 Did it take off flat out or just slowly? If flat out, it could be that the decoder was getting a bad DCC signal, interpreting it to be DC then taking off as full voltage is on the track all the time with DCC. This is well known and can be fixed by an adjustment to CV 29 to turn off DC operation. I would also be cleaning the track, wheels and pickups to make sure the loco gets a good DCC signal. All that said, it doesn't really explain the decoder burning out. I would certainly do as RDS says and return it for replacement as this shouldn't happen. Although just one thing here - I'm assuming we are talking about a relatively new loco here as an older one might draw more current than an 8249 can handle. Link to comment Share on other sites More sharing options...
Fishmanoz Posted September 2, 2013 Share Posted September 2, 2013 Did it take off flat out or just slowly? If flat out, it could be that the decoder was getting a bad DCC signal, interpreting it to be DC then taking off as full voltage is on the track all the time with DCC. This is well known and can be fixed by an adjustment to CV 29 to turn off DC operation. I would also be cleaning the track, wheels and pickups to make sure the loco gets a good DCC signal. All that said, it doesn't really explain the decoder burning out. I would certainly do as RDS says and return it for replacement as this shouldn't happen. Although just one thing here - I'm assuming we are talking about a relatively new loco here as an older one might draw more current than an 8249 can handle. Link to comment Share on other sites More sharing options...
Gingerman Posted September 3, 2013 Author Share Posted September 3, 2013 Fishmanoz said: Did it take off flat out or just slowly? If flat out, it could be that the decoder was getting a bad DCC signal, interpreting it to be DC then taking off as full voltage is on the track all the time with DCC. This is well known and can be fixed by an adjustment to CV 29 to turn off DC operation. I would also be cleaning the track, wheels and pickups to make sure the loco gets a good DCC signal. All that said, it doesn't really explain the decoder burning out. I would certainly do as RDS says and return it for replacement as this shouldn't happen. Although just one thing here - I'm assuming we are talking about a relatively new loco here as an older one might draw more current than an 8249 can handle. Link to comment Share on other sites More sharing options...
Gingerman Posted September 3, 2013 Author Share Posted September 3, 2013 The loco took off at about 12 throttle, after taking apart another loco and trying its decoder, ive come to the conclusion its a short as it did exactly the same thing. The loco was brought second hand and is the super detailed version of the schools class so relatively new in design. The other chip I tried was from another company, the loco would run very briefly as described and then short the system. With the r8249 chip in the loco would run away but not short the system? The only other thing I haven't mentioned was when it ran off the motor emitted a metalic sound from the motor! Have since ran it on on dc and no problems at all. Sorry for any grammar mistakes im typing on a phone and its proving tricky. Kind regards Link to comment Share on other sites More sharing options...
poliss Posted September 3, 2013 Share Posted September 3, 2013 Another thing you could do is to look very carefully at the socket to see if there are any whiskers of metal across the holes. On DC this won't cause a problem, but will cause a short on DCC. Link to comment Share on other sites More sharing options...
Gingerman Posted September 3, 2013 Author Share Posted September 3, 2013 poliss said: Another thing you could do is to look very carefully at the socket to see if there are any whiskers of metal across the holes. On DC this won't cause a problem, but will cause a short on DCC. Link to comment Share on other sites More sharing options...
Gingerman Posted September 3, 2013 Author Share Posted September 3, 2013 Thanks for the help gents, ive started to strip the loco down so I can work from the ground up and whilst I'm at it I'll give her a service. Kind regards Link to comment Share on other sites More sharing options...
Gingerman Posted September 5, 2013 Author Share Posted September 5, 2013 Got to the bottom of it! Tender pick ups were the culprit, wired the opposite way to the loco for some reason. Thanks for the replies gents. Link to comment Share on other sites More sharing options...
RDS Posted September 5, 2013 Share Posted September 5, 2013 @Gingerman I am pleased you have sorted the problem. Thanks for letting us know the solution. Link to comment Share on other sites More sharing options...
poliss Posted September 5, 2013 Share Posted September 5, 2013 Was it the pick-ups or had the wheels been put in the wrong way round? Link to comment Share on other sites More sharing options...
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