Hornby HST TTS decoder fitting & lighting circuit repair

[andyman7]

My son (11) used his Christmas money to buy the TSS (MTU) decoders for his HST set (Hornby GWR latest pattern superdetail versions). He is young enough to still assume that plug & play means just that, despite my attempts to advise that whilst it makes things easier, finding your way round modern superdetail models and dealing with the issues that arise is often a bit more challenging.

 

'No problem dad, I've got the bodies off' was followed by my observation that he had broken a number of the headlight lighting wires......

 

This thread:

 

Covered the older style circuit but since 2016 a plug in wiring harness is used. There is only one wire detached from the power car but proving impossible for me to get enough access to solder it back, so Question1 is 'does the little PCB headlight board pull out or is it glued or otherwise attached?'

 

On the dummy car, all 3 wires are detached at the PCB. I found the complete harness as a spare:

https://www.ebay.co.uk/itm/X7077-Hornby-Spare-Dummy-Light-Board-PCB-for-Class-43-HST/142962231264

 

But I can in this case, I get access to resolder the wires if I can decipher which pin goes to which terminal. I'm trying to work it out from the photo in the listing but any help would be appreciated.

 

On to the decoders themselves, the mounting screw holes in the dummy car cannot be reached by the supplied screws with the speaker housing as the weight is in the way. So much for plug and play, unless I am missing something. Rather than remove the weight I plan to use longer screws and a dab of blu-tack to seat the speaker on the weight. 

 

Any tipe or advice anyone might have with fitting these would help!

 

Many thanks and Happy New Year to fellow RMWebbers

 

 

[andyman7]

Well having taken a look at this with a cool head today, I've dealt with most of the issues and am sharing them here in case anyone else needs to know.

 

Fitting the TTS chips - the only issue in the dummy car was that despite the chassis having mounting screws for the speaker, the weight gets in the way. A dig in the spares box for a couple of longer self tapping screws lets the speaker housing rest on top of the weight, still plenty of room to get the body on.

 

The power car was fine although the supplied screws are not self tapping so won't bite into the chassis holes. Spares box again, sorted. Both chips wrapped in masking tape and enough room to get the body back on.

 

As for the lights - well a precaution I have taken is to tag the wires from the plug L - M - R so that if they become detached I know which position on the LED lighting board they go. This was fine for the power car because only one wire was detached, on the trailer all three have come off. The easiest solution was just to order a replacement X7077 harness, it won't go in the model as I'll keep it for spares but it will let m note the plug-to-PCB wiring order, I'll tag and resolder the wires in the trailer once it arrives. Meanwhile the boy is happily playing with the set, just minus one set of lights until that last job is done.  

[RAF96]

No sure masking tape is a good wrap idea as the glue may be bad for your decoders. By all means insulate metal bits like the weights with tape, but the decoders need air round them to avoid overheating,

[andyman7]

On 05/01/2020 at 09:13, RAF96 said:

No sure masking tape is a good wrap idea as the glue may be bad for your decoders. By all means insulate metal bits like the weights with tape, but the decoders need air round them to avoid overheating,

The instruction leaflet actually recommends a layer of sellotape (and says that this still allows for heat dissipation), but I didn't want the tape glue round the chip. I therefore chose a loose single layer wrap of masking tape because it is much lighter tack - I will monitor the situation though.

 

For anyone that needs it, I've attached a diagram to show how the lighting plug is connected to the cab roof and headlight PCBs: