Saturday, October 10, 2009

Can I light up these panels?

Cleaning off the indicators was a relatively straightforward task. If I did nothing else to the panels, they look much better now, and they'd be suitable for building into some sort of display. But I don't want to stop here. There is so much potential to make these beauties really "pop" back to life. Going to the next level means getting the indicators to light up.

I must state at this point that I am most decidedly not an electrical engineer, nor have I had any formal training in electronics. I do have some experience in building simple circuits to light LEDs in model airplane and rockets. I have a healthy respect for electricity, but I'm not afraid to experiment. Some of what I will describe here will be grossly oversimplified and the result of trial-and-error compared to what might happen if I actually knew what I was doing. I'm just documenting my learning process.

On the other hand, there isn't a lot of documentation for these panels. No instruction manuals or wiring diagrams have survived the past 35 years.

I knew from my experience with a segment from another control panel (see the thread here from that these panels use 28V GE 327 aircraft lamps. In my previous project, I substituted 12V equivalents of the lamps. I decided to stick with 28V lamps for this project.

The other decision point here is: do I use the existing wiring, or do I use alligator clips to attach to the Roto-Tellite power posts like I did in my other project? In my other project, the wires had been clipped off when the display segment was removed from the larger panel. The panels I have now are complete and (apparently) undamaged - no wires have been cut, and they are attached to the original connectors.

Here you can see a portion of the back of the S-IB Operations panel. It appears relatively straightforward, since it is only comprised of indicator lamps in Roto-Tellite enclosures. The primary concerns here are:
  1. Do the lamps work? Which ones are burned out?
  2. Are there any short circuits in the wiring?
  3. How does the connector map to the lamps? (i.e., which holes in the connector are attached to which lamps?)
The mapping task with the S-IB Networks panel is going to be a lot more complicated. In addition to the 49 lamps in Roto-Tellite enclosures, there are 8 analog meters, 9 individual lamps, a mechanical counter, 1 rotary switch, 18 three-position switches, and 3 push button (momentary) switches. There are 9 resistors on the backplane, and wires go to both posts on the frame as well as to 3 circular connectors.

So, let's start simple, with the S-IB Operations panel. To assist in documenting the functions of the panel, I created an Excel spreadsheet that lists each indicator and its position on the panel. There are location designations stenciled onto the back of the faceplate. For example, the "LOX LOADING REVERT" indicator is in the upper left corner of the panel, and it is labeled "DS1" on the back of the faceplate. The numbers run consecutively along the rows (DS1 through DS8 on the top row, DS9 through DS16 on the second row, etc.). I transferred these designations to the spreadsheet.

Now, it was time to see what worked and what didn't. For my first simple test, I wired two 9V batteries in series, figuring that 18V would be enough to produce at least a little light from the 28V bulbs. My past project taught me that the center post of each Roto-Tellite enclosure was the ground and the two outside posts were +. I connected the battery negative terminal to a center post, and then clipped the power alligator clip to the power post on the "ALL ENGINES RUNNING" indicator (DS23). Success! The lamp lit, probably for the first time in 34 years!

Two more alligator clips were attached, to the IGNITION and the LIFT-OFF indicators, just for fun at this point. Fortunately, the lamps in these indicators were still good, so they glowed as well. I dutifully photographed the indicators as my inspiration for lighting up the panels.

At this point, the simplest thing to do would have been to touch the positive alligator clip to a post on each indicator to see which bulbs were still working and which were burned out. I opted to combine two steps here, by also seeing which pin on the connector corresponded with which indicator.

The connectors on these panels are "24-61" connectors, which are standard military hardware. Each hole has a corresponding letter. Unfortunately, the placement of the labels on the connector for the S-IB Operations panel was pretty inconsistent. The letters were often not immediately adjacent to a hole. This quickly became a problem as I worked my way around the connector, sticking a probe into a hole and seeing which lamp lit, then making notes on my spreadsheet. By the time I had worked about 1/3 of the way around the outside of the connector, I was losing track of which hole corresponded to which letter.

To aid in my documentation, I needed to make a diagram of the connector, invert the colors on my PC (to make a better printout), and then draw lines connecting each letter to its corresponding hole. That way, I could ensure that I was being consistent.

I found that as I worked around the connector from A-Z, the lamps lit in order, running horizontally. "A" corresponded to DS1, "B" to DS2, etc. A little lesson I learned, so that I wouldn't have to keep craning my neck from the back to the front of the panel, was to put a mirror in front of the panel so that I could see the bulbs light up while I stayed at the back of the panel.

I found that the bulbs in nine of the indicators were burned out and would need to be replaced. I may be able to move some bulbs from unused indicators to the ones that need new bulbs. A little spark told me that pins aa and bb were ground, which I should have determined first, before checking the bulbs!

So now I have the connector mapped to the indicators in the S-IB Operations panel. This was also documented in my spreadsheet.

As I mentioned, I would like to explore powering this panel through the 24-61 connector rather than with alligator clips. I will need to find out what kind of plug corresponds to this receptacle. They are labeled "Burndy MS3124E 2461S."

Next time: What does it mean?

Friday, October 9, 2009

Taking a new direction: A restoration project

I've decided to take my blog in a different direction. It's still going to be dedicated to my space collection, but I'm going to concentrate most of the posts on a few items of particular interest to me at the moment: my control panels from the Apollo-era firing rooms at Kennedy Space Center.

I highlighted these panels in a previous post early this summer. I have started working to restore two of the panels, with the goal of "lighting them up" again and having operate similarly to how they might have looked during the launch of the Apollo-Soyuz Test Project in 1975.

I'm going to use this blog to document the process that I'm going through to bring these relics back online.

Let's start with general clean-up.

I purchased these panels from Steve Hankow at Farthest Reaches in June. Steve's consignor acquired them from the estate of Charles Bell. Bell was a NASA inventor and engineer who was involved in the Mercury, Gemini, and Apollo programs. He amassed a huge junkyard full of rockets, spare parts, control panels, test equipment, and just about anything that could be salvaged when NASA junked the items. Bell's materials were not catalogued or kept in environmentally-controlled conditions, so they were not in pristine condition (to say the least) when his estate was auctioned off.

The S-IB Operations Panel displayed the critical events in the countdown and flight of the Saturn IB, the first stage of the Saturn rockets that flew Apollo 7, as well as the crews of the Skylab and Apollo-Soyuz Test Project missions, into Earth orbit. Although I don't know for sure, I assume that this was used by a person in a supervisory function, who was monitoring the overall progress of the countdown.

The panel is a 19" x 5-1/2" bank of 40 indicator lamps in "Roto-Tellite" enclosures. Each enclosure has one or two 28V indicator lamps, a colored gel (usually green, blue, or red), a translucent white plastic piece, and a clear plastic insert with lettering stenciled on. In many cases, a lot of dust had accumulated in these enclosures when I opened up the panel. Also, the ink from the stenciled lettering had bled, and some of the gels may have melted slightly in the Florida heat of Bell's junkyard, causing the gel to wick between the indicator's plastic inserts. You can see that some of these labels were almost illegible from the accumulated grime.

My first task, after photographing the panel to document its original condition, was to clean up these plastic inserts. To do this, one first has to remove the inserts from the Roto-Tellite enclosures. You have to push on one side of the enclosure to rotate the cell. In some cases it was easier than others. These cells hadn't been moved in 35 years, so they were very reluctant to turn. Once the cell is rotated 45 degrees, you then have to pop open the clip on the end of the enclosure. This was particularly hard on my fingernails and fingers, and I was lucky not to get a lot of blood on the panel!! After opening the clip, the plastic insert can be slid out. In some cases, it was stuck to the enclosure and had to be gently loosened with an X-acto knife.

The plastic inserts were generally stuck together. I was able to separate most of them into their component pieces using my thumbnail at the corner of the insert, gently pulling the stuck pieces apart. I tried a variety of methods, starting with mildly soapy water, to clean up the plastic inserts. Soaking in water didn't get rid of the gunk. I found that the colored gels and the translucent white pieces could be rubbed clean with a paper towel with a little rubbing alcohol on it.

With the lettered inserts, I wasn't sure if rubbing alcohol was a good idea. Gentle rubbing with a paper towel accidentally rubbed off the ink on one letter, much to my horror. I switched to rubbing alcohol, applied gently with a Q-tip. That worked much better and didn't seem to damage the lettering. In 90% of the cases, the Q-tip removed the dirt and left the letters intact. In a few cases, though, the ink seemed to start to dissolve in the alcohol, so I quickly dipped the label into water and blotted it dry.

After drying each piece of the insert, I reassembled them and put them back into their original cell. You can see here the side-by-side comparison of this one bank of indicator lights, before and after cleaning off the "LOX TANK PRESSURIZED" indicator.

Repeat forty times, for this panel...and forty-nine times for the S-IB Networks panel. But the end result was well worth it. All of the indicators survived the cleaning process, with the loss of only one letter on one label. Below are comparisons of the two control panels, before and after cleaning up the inserts.

Next time: Testing the lights and connectors!