Highbridge resurgent

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Paul Townsend
Posts: 897
Joined: Mon Sep 14, 2009 6:09 pm

Highbridge resurgent

Postby Paul Townsend » Wed Oct 13, 2021 10:11 am

Second switch on was Monday am Oct 11th. with me alone to allow fresh(ish) brain to focus.

Pong traced to exploded tantalum capacitor on one of my DiY logic PCBs of which there are 12, each with 8 channels.
These PCBs are of 1980s design and use CMOS logic to accept push button inputs and provide ouputs to control panel LEDs and my TOUs which are good old PO 2000 relays.....since I have around 80 turnouts on Highbridge, I used these as free of charge ( ex BBC Studios ! ) and way back then pennies were short.
The dead C put a near short on the 5v logic supply in the fiddle control panel, dragging it down to 2.4v

C changed, pong dissipated, 5v now OK so all FY CP leds etc work again.

I then started the complete track clean required since little train running had happened since May when I started to feel mega-grotty.

Due to unusuallly long hiatus, I plan that every inch of track will be run over by both my track cleaning machines, at least twice in each dirrection.
First is the self powered Parcels van No.34 which applies the Pendon style hardboard pad, thus very gentle abrasion ( similar to the French technique whereby track is cleaned with wine)
Second is a run with my CMX tanker filled with heptane (I used to use IPA ). This vehicle is so heavy that the only way I can shift it up my 1:40s or over complex pointwork, barrow crossings etc is to have a dedicated diesel. This is a Bachmann Class 25 acquired dirt cheap at Warley several decades ago. It was sold as chassis only, no body so I pretend it really aint a diesel! Well after all this is 1913 :D

Results so far are encouraging. The GWR up and down circuits main lines and most FY through roads are now clean. GW Goods Yard, Down relief loop and up relief siding are not yet done. No S&DJR track has been assaulted yet.

I had anticipated two categories of faults arising from the over cooking incident during the July heatwave ( 40degrees C for a day or three).
1. Broken dropper wires. Track is all Brook Smith using original Studiolith brass tags under rivets to the actual TCW dropper.
2. Buckled rail ends where gaps cled up and bumped each other, thus probable fractures of the solder joints to rivets and/or brass screws providing support at baseboard joints.

Surprisingly, when Tim and I ran trains on Monday evening, much of the track run over so far is free of above faults.
However the predominate failure is lateral displacement of rails at baseboard joints. There are 3 such BB joints out of the 13 that carry GWR tracks.
The further 8 BBs that are unique to the S&DJR have not yet been tested.

The 3 BB joints that are embarrased include two in the station area that have had a history of needing adjustment once or twice since H/B was rebuilt in its new home 5 years ago. These only carry two or three roads. The third is in the middle of the FY and carries 13 tracks, Bug%$r.

I will assault these faults soon and anticipate it will take a full day of slackening BB joining bolts, adjust and retighten, resoldering etc
You will ask why didn't I use proper dowel BB aligners! I did where ever possible but on a circular layout, to enable a BB to be lifted out ( admittedly a rare event ) there are issues about sliding BBs apart enough to split the male/female dowel joint. This was resolved by a few joints being made with two female dowels and a 6mm steel pin to align them. Guess which joints have this technique used?

Once the 3 offending joints are sorted I will turn to the S&DJR.

Normal running will be resumed asap :D

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steve howe
Posts: 659
Joined: Sun Feb 01, 2009 10:16 pm

Re: Highbridge resurgent

Postby steve howe » Wed Oct 13, 2021 12:55 pm

All power to your elbow Paul, we are currently embarking on a major de-bug on Watermouth following the completion and installation of the new control panel about a week before we were plunged into lockdown 1. Systematic working through each route with a meter seems promising, the main issue being the polarity of turnouts through the new cobalt motors, but as there was always a 50/50 chance of the wires being the right way round to begin with its an easy fix.

Old layouts! we love 'em!


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Paul Townsend
Posts: 897
Joined: Mon Sep 14, 2009 6:09 pm

Re: Highbridge resurgent

Postby Paul Townsend » Wed Oct 13, 2021 2:53 pm

[quote="steve howe"
, but as there was always a 50/50 chance of the wires being the right way round to begin with its an easy fix.

Old layouts! we love 'em!

If you have a lot of turnouts Probability Theory predicts that exactly half will be the wrong way round.
The question is "which half" :twisted:

Terry Bendall
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Posts: 1977
Joined: Sun Jul 27, 2008 7:46 am

Re: Highbridge resurgent

Postby Terry Bendall » Thu Oct 14, 2021 7:54 am

Paul Townsend wrote:Old layouts! we love 'em!

Indeed. The Mid Sussex Group's model of Pulborough was started in 1984 and took 11 years to get to a fairly substantial state of completion. This shows in the wiring, quite a lot of which has been redone in the last couple of years but things still catch us out. The model was shown at the Bluebell Railway model show in July and a fault developed which put the up loop out of action. An investigation after the show showed no problems and the section worked fine on the next occasion!

Keep up the good work Paul.

Terry Bendall

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