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Oscilloscope Roundhouse

November 19, 2012

Having (almost) finished refurbishing my deck I decided to play. Many of you are old enough to remember steam locomotive roundhouses. I am as interested in steam railway traction as I am in vintage electronics; many years ago, I was involved in a minor (very) way in the restoration of Bullied West Country Class Light Pacific 34105 “Swanage”. The “actual” locomotive below is a Hornby Stephenson’s Rocket which came out as a limited edition some 30+ years ago (I think 1979ish). It is live steam powered by butane gas which is held (mostly not held) in a small cylinder that is hidden in the faux water barrel. It was hard to get it hot enough to quit spewing gobs of oily water out of the stack however, once hot it could pull surprisingly well. There are videos on Utube showing examples pulling 3 or 4 carriages around outdoor 3 1/2″ gauge tracks in the UK. I filled the gap between the boiler tube and the sheet metal case with vermiculite (granular expanded mica) which helped things quite a bit. Anyway, here is the roundhouse:
The ‘scopes are going CW from the exit track, Tek 310, OS-8E/U, USM-32, Siemens 05, Telequipment S31, Triumph 830 (wobbulator/’scope), Tek 310A, Tek 310A. At the time, they were all fully operational.


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  1. Bruce Baur permalink


    I love it! I guess the 511 was just to big and heavy to display with the little guys? My brother is into speeders, 5 or 6 at this time.

    A couple of notables. I just recently brought up the Tek 519 and the 7912AD at the museum. The 7912AD works now, but needs some tuning up as soon as I can find a manual. Amazing what can be done without schematics, but they sure make it easier if you have them. The distortion on the 7912 monitor is a monitor issues, not the 7912. The bottom graticule is cutoff by a 7912 problem. On the 519, the display is a ‘reflection’ of my termination from a 90 ohm generator to its 125 ohm input impedance and the clips connecting the two. We now have the proper 125 ohm GR connector and 90-125 ohm minimum loss converter.

    I hope to see you out here one of these days,


    • Hi Bruce.

      Thanks for the appreciation! I chose scopes that are proportionate to the 3 1/2″ gauge track and the Rocket.
      I am not closely familiar with the scopes you are currently working with which is of course, not surprising. I am very pleased that the museum exists and yes, I am sure I will visit one day. You can be sure that if any other reason calls me to your area, spending time at the museum will be a top priority!


  2. Hi Richard,

    I have enjoyed your blog and website. Interesting to run across others where the same common interests are such an unusual combination, steam and old oscilloscopes. I own a foundry and machine shop, and restore vintage marine steam engines for a living, a very narrow niche to be sure! And I love old o-scopes, though I don’t know much about how they work. I had a question about a very small one I acquired off eBay some time ago. It is a tiny Waterman Primer-Scope, used for training and for very basic troubleshooting. It has three 12ax7 tubes and a single 12ax7a, one of which presumably is used for the sweep. The internal sweep tries to work when first warmed up, but only goes halfway across the screen, then it drifts completely off the left hand side of the screen. I can see it still blinking off to the left (with the sweep time base is set to the slowest speed). Also, I get no response from the external trigger. Do I have a bad capacitor somewhere? I have shunted most them I can get at, with good ones, with no change. But there are at least three I simply can’t reach without taking the scope completely to pieces. Clearly I am sustaining no sawtooth voltage, but the oscillation and the blanking are working. What should I look for? Could a bad resistor cause this? All the tubes test OK, and I have even swapped them around in the different sockets with absolutely no change in the scope’s behavior. I would love to get this little chap functioning! Of course, it is rather useless as a usable scope, compared to my larger ones, a big Tektronix 561, two TeleQuipment D54’s and another British scope, an Advance OS1000a. The Advance and Tek are my two favourites, though the Tek is a huge thing and an absolute killer to carry around. At any rate, I will appreciate your insight on what to look for. I wish I had a schematic for the tiny scope but online searches have never turned up anything but a basic users’ manual and the occasional photograph.

    cheers, Stewart M.

    • Hi Stewart.

      Thanks for commenting! Yes, we share unusual interests and I bet it goes further than we have seen! Years ago, I participated a little in the restoration of Bulleid “West Country” Pacific 34105 Swanage.
      Where is your shop? (I guess I may find out when I visit your site.) I would like to visit with you when I come to England sometime. This year I am going to the south-west of France and while there will be visiting with Marc Mislange who created, and is curator of, the HP Memory Project (Google that, it is worth it). The HP side of my collection is building quickly, this weekend I restored a Model 500B frequency meter. It predates frequency counters and is a fascinating device and works rather well though I re-stuffed two electrolytics and have a pile of leaky paper in oils from it. Which brings me to your scope. You say you have shunted caps. If they are leaky(as in leaking current though oil leakage may be visible as well), shunting (connecting in parallel) will not help, you need to replace the caps. If by shunt, you did mean connecting another caps in parallel, then I think replacing the paper in oil caps will quickly move things in the right direction.
      Best wishes,
      Richard Sears

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