Odd electrical problem - Hornby class 50

[PoshPaws]

I have a Hornby class 50 which came from eBay and started life as 50018 Resolution. When run on analog power it runs normally and the lights are fine. When I remove the blanking pcb and install a dcc decoder it shorts out the whole system. I have tried a few different Zimo and Lenz decoders, including three that work fine in their normal locomotives, so I'm pretty sure the issue is in the locomotive itself.

 

Does anyone have any suggestions for where to look first, or know of anything that is connected under dcc but not analogue? This one has me scratching my head and sending it to Hornby isn't an easy option as I live in the USA.

 

Many thanks

Mike

[markw]

The early releases of the Hornby class 50 had faulty circuit boards that connected one of the function outputs directly to the positive common.

At the time Hornby would supply a replacement on request.

[34theletterbetweenB&D]

There might be clues to a DIY fix in this (rather large) thread:

http://www.rmweb.co.uk/community/index.php?/topic/366-Hornby-class-50s/page-16?hl=%26quot%3Bclass+50%26quot%3B+dcc+problem&do=findComment&comment=2784815

[Pannier Tank]

One of many topics on this subject. http://www.rmweb.co.uk/community/index.php?/topic/57160-Hornby-class-50-dcc-problem/

[PoshPaws]

Thank you for the fast answers. So it was as simple as put the decoder in backward and change the direction CV. Glad I asked here first.

 

Mike

Edited November 25, 2017 by PoshPaws