gazzavc Posted October 17, 2023 Share Posted October 17, 2023 I recently acquired one of these from a 2nd hand model shop here in Los Angeles. Trying to program it with my MRC Prodigy Express DCC unit has been an exercise in frustration as it doesn’t seem to recognize the chip. The loco runs fine using DC power but I’d like to get it running on DCC if possible. I did verify that the chip is present in the loco. Any help would be appreciated 🙏🏻🙏🏻 Link to comment Share on other sites More sharing options...
RDS Posted October 17, 2023 Share Posted October 17, 2023 HiPlease post a picture of the chip installation. Link to comment Share on other sites More sharing options...
Bulleidboy Posted October 17, 2023 Share Posted October 17, 2023 HiAs this is DCC Fitted, I would assume it would have been fitted with either the R8215 or the R8249 decoder which was the replacement for the R8215. The R8215 was the first decoder Hornby introduced, and until very recently was the decoder I had fitted into my Class 08 - it ran well. I am not sure if the R8215 was NMRA compliant - the R8249 was. Link to comment Share on other sites More sharing options...
Going Spare Posted October 17, 2023 Share Posted October 17, 2023 Coming from set R1075, this loco should have the factory-fitted 4-pin decoder which I believe carried part number X9659 and may be the same as what is now offered as R7274. Link to comment Share on other sites More sharing options...
Fishmanoz Posted October 17, 2023 Share Posted October 17, 2023 I agree with Going Spare in all respects. I have the set, my first purchase this century. Link to comment Share on other sites More sharing options...
ColinB Posted October 17, 2023 Share Posted October 17, 2023 I think I had this issue with one of the early Hornby decoders, someone on this site identified that there were issues with these early decoders. I think in the end I binned it, converted it to six pin and used a Zimo decoder. Link to comment Share on other sites More sharing options...
gazzavc Posted October 18, 2023 Author Share Posted October 18, 2023 HiPlease post a picture of the chip installation. Link to comment Share on other sites More sharing options...
RDS Posted October 18, 2023 Share Posted October 18, 2023 That's a very good picture. Can anyone confirm the chip and offer any advice. Link to comment Share on other sites More sharing options...
Going Spare Posted October 18, 2023 Share Posted October 18, 2023 Yes, as expected it is the Hornby factory-fit 4-pin X9659/possibly R7274. Link to comment Share on other sites More sharing options...
96RAF Posted October 18, 2023 Share Posted October 18, 2023 Compare Link to comment Share on other sites More sharing options...
Going Spare Posted October 18, 2023 Share Posted October 18, 2023 So, although the images are of one top and one bottom surface of the two decoders judging by the cable connections, it looks as if X9659 and R7274 are not physically the same (do they act differently?) and the OP's decoder giving him compatibility problems is the X9659. Over to those with the DCC know-how. Link to comment Share on other sites More sharing options...
Bulleidboy Posted October 18, 2023 Share Posted October 18, 2023 Sorry, I was not aware that some factory fitted loco's came with four pin decoders. Link to comment Share on other sites More sharing options...
Brew Man Posted October 18, 2023 Share Posted October 18, 2023 Yes, back in th' olden days. Link to comment Share on other sites More sharing options...
96RAF Posted October 18, 2023 Share Posted October 18, 2023 So, although the images are of one top and one bottom surface of the two decoders judging by the cable connections, it looks as if X9659 and R7274 are not physically the same (do they act differently?) and the OP's decoder giving him compatibility problems is the X9659. Over to those with the DCC know-how. The X number was simply the spare part designation on the service sheet. The R number being the retail packaging SKU. No difference twixt the two operationally. The only physical difference may be the colour of some components as production rolled along. Link to comment Share on other sites More sharing options...
Fishmanoz Posted October 18, 2023 Share Posted October 18, 2023 That picture is not original if my memory serves me correctly. The decoder should be direct plug not harness. No matter though, they are all 8249 variants. Link to comment Share on other sites More sharing options...
ColinB Posted October 18, 2023 Share Posted October 18, 2023 Either way whether it is "Plug in" or on a harness it should program that is something to do with the electronics. I must admit I rewired anything with 4 pin because it is Hornby unique, but looking at the photo the outer wires are supply, the inner wires motor. So basically you can plug it in upside down and it should still work it will just drive backwards. As I said in my first post it is a replacement fix. Personally I would rewire it as a six pin if your skills are up to that, then your choice of replacements improves dramatically. The easiest way I have found to do it is buy a Pecket DCC socket which is 6 pin and the PCB is a decent improvement to the loco. Link to comment Share on other sites More sharing options...
Howbi Posted October 18, 2023 Share Posted October 18, 2023 gazzavc.....have you tried resetting the decoder by writing value 8 to CV8. This will reset to default with an address of 03. Link to comment Share on other sites More sharing options...
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