Unusual - Shorting - R3677 'New tooling' streamlined Coronation.

[atom3624]

This is an unusual one.

I've an R3677 streamlined Coronation - Duchess of Hamilton.

Superb runner normally, but had previously had a shorting problem, which has returned.

 

I've separated the loco and tender - when placing the tender on the tracks, power supplied, there's no problem - no short.

When I place the locomotive on the track, it shorts, power cuts - HM2000 - DC operation.

 

When I invert the locomotive and try powering individual driver pairs, it shorts.

BUT

When I remove the baseplate with integrated pickups and WIRE sander pipes, THEN touch the wheels, it's fine.

 

When 'feeling around' I had been pleasantly surprised how robust the sander mouldings were until I realised they were metal wires - obvious now.

When touching LH / RH sanders of one pair, there's no short - obviously separated.

When touching LH / RH the other pair of sanders - there's 4 wires - 2 each side - it shorts out!!

 

I have raised this with Hornby - perhaps they can send a replacement baseplate with pickups - it's all integrated and 'sealed in' with a second piece of plastic bonded to the main one, holding in the contacts and the sanders.

 

I'm suspecting the sander pair which shorts out is touching the pickups, and/or is connected ... seems obvious, but inaccessible.

 

I'll see what Hornby have to say, just reaching out in case anyone else has encountered this - or even has a baseplate spare they can sell on ...

 

Al.

[atom3624]

I found if I moved the 'offending sanders' there was a moment they didn't short out, yet appeared in much the same position ... 

 

I might try this jiggling a little over the weekend and see if it'll work.

There's no way of opening it up without destroying it - top / bottom are sealed together trapping the sanders and pickups within.

 

Al.

[atom3624]

Right - possibly SORTED - not shorted!!

 

The problem seems to relate to the sanders - one of the 'pairs', not the other.  Must be touching the pickups.

 

It IS one piece.

Sanders appear to be 'hot glued' onto the outside of the baseplate. I tested out if it was one piece / shorting, and it was, and came off when warmed a little.

 

I tried the plate in place on the locomotive, without the one-piece, 2-sides sanders which fell off - photo - and no short!!

I've now snipped into 2 pieces and glued separately into position - SHOULD BE sorted ... will advise.

 

 

 

Very frustrating, but all part of the modelling experience I suppose!!

 

Al.

[atom3624]

Well, 'the offending article' was split into 2 and superglued back into place.

 

Plate was replaced onto the chassis, taking care with the 'fingers' - easy to misalign.

 

NO SHORTS.

Locomotive was reassembled - running very well.

 

I cannot say 'perfectly' as there's a 'chattering' of the gears - I had replaced the motor / worm as there was a moment of harshness, even when oiled of the original - DoH had been running quite a lot.

Gears have been realigned quite a bit - only one you can actually position is that on the final drive shaft / centre drivers - this might be slightly out.

 

RUNNING WELL, NO SHORTING!!

 

Al.

[atom3624]

Another thing ....

This loco's damned sensitive to quartering!!

I mentioned the 'chattering'.

I'd tried all manner of things - including old Coronation gears - same diameters, different widths, same overall width - double gear driven by the worm.

 

The locomotive was NOT super-smooth at a crawl, but this time it coincided perfectly with wheel revolutions - 2 'tight spots' per revolution.

Off with the coupling, connecting and valve actuation rods ... again ... after I had reviewed the alignments - VERY slightly out.

 

I've had others be more out than this and run perfectly - possibly it's lack of wear in the coupling rod holes - fortunately (not valid for the other locomotives I intimated!)

 

ALL RUNNING WELL NOW as I touch tons of wood - including my head!  This includes a decent and smooth crawl.

 

I think this story's over - not mentioning a couple of wires which had to be resoldered with all of the removal and replacement of parts ... done.

 

Al.