Problem with King George V R3330 Decoder

[sparrow hawk]

I purchased the King George V from a well known acution site. Had locos  before no trouble. tested loco on DC Ran ok. I then put a spare Decoder in that I had  ,and it got fried

I know I should have sent it back, But the engineer in me wanted to find out what was wrong. after much testing and thinking it must be the motor. I checked the connections all ok. I thought I would try again on DC .All was ok. 

I then put another old Decoder I had in that  I new was ok. would not read any C.V..

my Last thought was to undo the DCC Socket in the tender, and check the connections  under neath the socket,  and this is where the fault was .

in Manufacture the wires had been Squeezed together under the socket shorting out a couple of the pins, It caused the fault but only on DCC. I managed to free them apart, Bit of blue tack to keep apart and now runs like a dream.

I Just hope this helps if anyone else has the problem and saves a decoder from destruction.

I would suggest before you fit the decoder just unscrew the DCC socket and check before you install the decoder.

[Rog RJ]

The problem you found is not uncommon.  Usually its a sliver of solder between the socket pins or the pins touching on the chassis.

 

After fitting a decoder you should test the installation by reading the address on the programming track before allowing the loco to go on to the main track.  The programming track is current limited (except on the Select) to prevent damage to the decoder by faulty wiring and connections.  If you can read the address OK, normally 3 on new decoders, then write a new address - anything apart from 3 and read the address again to make sure the address has registered.  Then try it briefly on the main track before fitting the body and again check that you can read the address on the programming track before replacing it on the main track.

 

If you are fitting a sound decoder to a previously un converted loco, fit a non sound decoder first, make sure everything is OK and only then fit the sound decoder.  It's a lot less expensive to fry a non sound decoder than a sound one if the worst should happen

[Fishmanoz]

The actual thing to check is that the socket pins that will take the orange and grey wires (pin numbers will depend on the pin arrangement) are not shorted to chassis, just as you have to ensure with brush holders converting X03/04 and ringfields.  It's that short between input and output that does the decoders in.