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The Randall Museum in San Francisco hosts a large HO-scale model model railroad. Created by the Golden Gate Model Railroad Club starting in 1961, the layout was donated to the Museum in 2015. Since then I have started automatizing trains running on the layout. I am also the model railroad maintainer. This blog describes various updates on the Randall project and I maintain a separate blog for all my electronics not directly related to Randall.

2018-08-22 - Something Unexpected

Category Randall

This was rather unexpected:

The passenger automation currently runs with two UP engines. Then once the passenger train goes back to the station, the RDC goes out. Although they use the same track, they shouldn’t be on the same block at once.

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2018-08-11 - Today’s Saturday Running

Category Randall

For a change of scenery, today’s Saturday running has the TGV Atlantique in Multiple Units:

The TGV going over a wooden trestle bridge is a contrast that I enjoy every single time:

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2018-07-18 - Automation and Electrical Power Control

Category Randall

Four days ago, a derailment of the Amtrak train occurred. This was left unattended for a while. The end result is that both trucks on one of the Amfleet coaches melted. I didn’t even have a remote idea this was possible. I did not get a chance to see the damage first hand nor how it occured. One possibility I can consider is that there was a short and it lasted long enough to somehow produce heat and melt the trucks.

Photos: J. Evans.

That left me speechless. Not for long though.

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2018-07-01 - RC Filters and DCC signal quality

Category Randall

From the always excellent Gurries’ web site:

One thing I have experienced a few times at Randall are unresponsive engines. Luckily it is not a very frequent thing and each time I have seen it only on very specific engines. My first TGV unit using a custom LokSound V3.5 had the issue -- when running it after a while on very busy Saturday ops days, it would sometimes cease to reply. I “fixed” the issue by switching to another decoder, a newer LokSound V4.

However I have seen the same issue with other operators’ engines. Very very specific ones, and luckily not that many. I can think of a handful of cases.

A while ago that made me think whether using “snubbers” (RC filters) would be a possible choice, and if yes, where should they be located. Thus the link to Gurries’ web site above.

Unfortunately, when I read his “ideal bus wiring”, it seems to me that the Randall’s wiring is hitting all the wrong spots.

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2018-06-20 - Randall Repairs: Turnouts T370-T371

Category Randall


Turnout T370 + T371 (between bridge and signal bridge on Summit).


Cold joint at junction between B360 and T370.

Summary Fix

Bond wire around B370 and T370 rail (engineer side).

Description of Issue

Reports of trains stopping on turnouts T370 / T371, between bridge and signal on Summit.

Tried running two engines (GP9 5913, F40PH 506 from automation) and easily encountered the issue.

Measured voltage when engine stops: there was none.

Pushing the rails or the frogs (even so slightly with the voltmeter) immediately fixed the issue.

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2018-06-16 - RDC is back (soon)

Category Randall

After what took like forever, the Randall’s RDC engine is finally working again. This is what it looks like:

You’d be right to ask “what the heck am I looking at here?!!”. Very fair to ask. You are looking at a Rapido SP-10 RDC disassembled, with the motors being in the process of being replaced.

Let make me this clear: if your Rapido RDC stops running, save yourself some trouble. Contact Rapido’s support, and ask them to fix it for you. You’ll save yourself a lot of trouble.

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2018-04-07 - Randall Repairs: Turnout T05

Category Randall


Turnout T05 (Stockton Front Yard).

Turnout toggle button.


Trains stop on turnout / short the block after.

Examination indicate frog has wrong polarity when T05 is Normal.

Summary Fix

Spring fallen in the Fulgurex contact that reverses the frog polarity.

Description of Issue

There are two totally unrelated issues that make turnout T05 hard to use. Make that three issues.

Toggle button issues:

  • Turnout toggle button is loose. It rotates.
  • Turnout toggle button is a 3-position and not a 2-position.

Frog issue: Second issue is an incorrect polarity on the T05 frog.

T05 is a double cross-over. When straight, the frog in mainline track 1 tested as having the same polarity as the lower rail.

What should be expected:

  • There’s supposed to be a gap between the track 1 & track 2 segment cross-overs.
  • The frog is controlled by a Fulgurex to draw power from either rail A or B.

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2018-03-30 - Doodlebug

Category Randall

Here’s an interesting experiment for the branchline automation: using a Doodlebug.

This one comes courtesy of Martin Perry, who bought the Doodlebug and coach back in the 2000s. In 2005, he relettered both cars and donated them to the GGMRC for the Branchline operation, so it would be quite fitting to have it run today on the branchline automation. The engine is part of Bachmann’s Spectrum line and ten years later still works like a charm.

Since I have no record of when maintenance was done on it, I should probably open it and lubricate it before using it for daily automation. Right now it’s on “probation” to make sure it works and does not derail on the branchline dual-gauge turnouts… these have been doing fine so far but I’ve had some not-so great experience running a previous 2-6-0 engine right there a couple years ago.

2018-03-28 - Error Conditions

Category Randall

Now that we have some basic automation running and, most importantly, some feedback on how it is running, it’s time to account for error conditions. The post from 2018-02-12 did mention that earlier but it was more academic with any actual basis. Now I do have basis:

  • On the Branchline, a repeated issue is the RDC failing to stop and reverse on the reverse block.
  • Now that the RDC is moved to the mainline, I did experience the same issue at least once. However that’s not clear cut as in this instance I was also trying to update/restart RTAC remotely. It happened in a second instance for the RDC.
  • At least once the same issue happened with the Amtrak train.

That picture is, ironically, exactly what I want to avoid and which happened:

In trains parlance, this is called a runaway.

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2018-02-28 - Atlas Master Amtrak GE Dash 8-32BWH

Category Randall

So it’s the beginning of January 2018, I am being told the museum opens in one month and I have two engines that are constantly derailing. Not a good way to demonstrate that automated train layout that I’ve been working on for the last 2 years (or at least trying to, when I had access).

Logical plan: have backups. Nothing new, I had mentioned this multiple times in the past. In an effort to move on towards that goal, I got hold of some of the previous GGMRC-owned engines appropriate for the task, namely three P42 and three GE Dash 8-32BWH. The P42s seem in dubious shape, having run quite a lot.

The three GEs seemed better. One was still DC and two had their original Atlas decoders and seemed to run adequately. These are from the Atlas Master line, and came equipped with dual DC/DCC decoders.

After some lubrication (and learning the hard way how to take the shells off) followed by basic speed matching, two GE Dash 8-32BWH are used in the automation program and we get through the Randall Museum’s Reopening Ceremony fairly well, including two follow up Saturday.

The third Saturday is the Science Fair exhibit at the museum. Very large attendance. Record on the RTAC tablets show that the branchline RDC ran 120 times (!) and the Amtrak train ran 45 times.

And by the end of the day one of the engines stalls on some turnouts.

I take both engines home, remove the shell and realize that one of the motor is… smoking :-/

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