ElephantAir 737 Flight Simulator: Overhead

Forward overhead is from FDS, and it's non-IBL version. Or, to be more precise, only one panel in it is IBL panel.

Overhead (as arrived) on a stand in my workshop:

Aft overhead was ordered in the middle of November 2014 from www.cockpitsimparts.co.uk. As of June 2015 it is not assembled yet.

June 24, 2015

Electrical panel built on 7-segment indicators.

I bought four Display driver boards and related 7-segment indicators parts from Wendy some time ago ( http://www.flightsimparts.eu/Shop_7Segment.html ).

Now, when Overhead wiring is mostly completed, I went around to build and install Electrical panel, along with FLT/LAND Alt indicators.

Two Display driver boards are used for Electrical panel. I built Electrical indicators using Wendy's 3-digit boards.

For upper row I assembled two boards with 2 and 3 digits.

Lower row has 3 boards with 2, 3 and 3 digits. I added one digit for AC Amps indicator, since I've read on the Prosim forum that it could be over 100 amps.

First I tested the newly built indicators with Pokeys card.

Next, I built the actual panel and installed the indicators on one side and Display driver boards on the other side of the panel.

I had to make some extra cuts in the panel to pass the wires from one side to another, so they do not interfere with other wiring on overhead.

All the wires are soldered from back side of indicator boards (which kind of goes against board design :) ). This is because I wanted to have front side completely flat *beside the indicators in order to install the rubber foam mask that blocks any light leaks from inside the overhead.

The mask was cut from he same rubber foam mat that I used for glareshield trim. It was thicker than necessary, so I cut a thinner layer from it.

The indicator holes in the foam are slightly smaller than indicators themselves, so it provides tight fit.
After few tests for panel position I pressed the whole assembly with the foam mask against the actual electrical panel opening in the overhead and then cut the outside the mask to make it slightly larger than the footprint from the opening.

This tight fit prevents any light leaks in the panel.

The 4 connector wires (3 signal and ground) from each Display driver board go to the 25-pin connector and then through the cable to Pokeys card. The Display driver boards use Pokeys ports 9,10,11 and 23,24,25.

The covering glass was cut and filed to proper shape. It is made from plastic transparent clipboard that I've bought at business supply store. There was one perfect smoked-glass among clipboards of many colors.

Light test:

And the final shot of working Electrical panel:

The configuration for Electrical panel in Prosim is on Numerical tab:

FLT/LAND Alt indicators built on 5-digit boards with amber indicators and also use two Display driver boards.

Obviously FLT/LAND Alt indicators are connected to another Pokeys card since single Pokeys card supports only two Display driver boards on ports 9,10,11 and 23,24,25. (this is by default without using the other possibilities of Pokeys card).

FWD Overhead assembly

The work on overheads took almost a year. Of course it was not full-time job. :)

All the wiring and testing were done on a stand in my workshop. And then all overhead stuff was moved into the sim. Scary thing - it started to work in sim right away. :)

Overhead wiring design.

The wiring approach to overhead is the same as with MIP. There are three wooden bars with DB25 connectors installed on overhead back side.

On the bars there are several grounding PCBs with 0.1" pins connectors. All ground wires from different overhead panels just go to those ground pins. These grounding PCBs are connected to Pokeys card ground through common ground wire.

There are also separate PCBs power buses with screw-in connectors. They are for:
- LED backlighting sub-panels (12V)
- Gauges backlighting (5V)
- Few FDS IBL panels backlighting (5V) as well as all PCBs providing +5 and +12V power to LEDs and instruments backlighting.
- whatever else power needs, like 7-segment indicators.

The overhead control board unit is separate from overhead itself. They are connected through set of DB25 cables.

Overheads connected to control board by 15 6-foot DB25 cables. During workshop testing and initial setup in sim I used 10-foot DB25 cables. And yes, despite of all advices to make wiring as short as possible, Pokeys cards work just fine with wiring that is over 10 foot long. Here is the scary workshop photo :)

DB25 connectors placed the way they can group the nearby annunciators and switches for the connectors in order to provide shorter and less cluttered wiring on the overhead. Generally, there are two groups of DB25 connectors: 5 for annunciators and 6 for switches on FWD overhead. Of course, there are few wire exceptions here and there.

I used green and blue LEDs for corresponding annunciators and white LEDs for the rest of amber annunciators. They all have amber filters behind legend plates.

Dual state annunciators have 3 LEDs. Normal state uses one LED and Bright state turns on 2 other.

Beside each annunciator connector there are extra PCBs with 3 rows of pins. Two rows for signal
connections - one goes to DB25, second (ground) to the annunciator. Third row is common +12V bus for LED power. This follows the same design as for MIP buses.

To wire the annunciator I just need to plug the ready-to-go 2-pin wires into the selected bus row and to annunciator pins. Second small wire connects the signal pin with DB25 pin. No soldering here.

From switches the connecting wires go directly to the DB25 connector pins.

This approach provides easy access to every wire in overhead. Any overhead sub-panel panel can be quickly disconnected and taken out for maintenance.

The only control cards that are directly located on the overhead are for 7-segment indicators (from Wendy).

The overhead control board has four functional areas.

Main input power subpanel - contains one 12V 180W PSU, three 5V 30W PSU, the fuses module and power distribution box.

- First 5V PSU is dedicated for Pokeys Ethernet cards that need 5V power.
- Second 5V PSU is for powering the IBL panels and real gauges backlighting.
- Third 5V PSU is for any other 5V needs in overheads.

Two identical control modules with installed Pokeys cards, LED extension boards, DB25 connectors and additional power switches. Those switches can be used to recycle power to the cards only if necessary.

Output power module includes:

- 12V and 5V terminals that feed FWD and AFT overheads .
- 4-relays block to control overhead power. Relays are operated by DC Power switch.
- 16-port network hub.

Here are some pictures from control board design time that took place on a patio :)

The overhead control board hangs on hinges, so it can be "opened", or easily taken out and moved to workshop if neccessary.

The main control module was located initially on the left back side of the sim shell.

But it was not convenient to walk around the sim with control board installed on its side. So I moved it to the shell roof where it overhangs sim entrance area.

The control modules in normal use are closed with plastic covers.

This design provides the easy access for maintenance. And yes, it's a bit more complex design than common approach where wires directly soldered to switches and control cards.

AFT overhead design follows the same approach and has four more DB25 cables. There is a cooling fan installed inside AFT overhead to provide both overheads with cooling air, if necessary.

The total power consumption by both overheads is ~100 watts.

I have two 12v buses in the overhead. One is straight 12 V and used for annunciators. Second 12v bus runs through the dimmers (dimmers are separate for FWD and AFT overheads). FWD overhead LED flood light is also on a separate dimmer.

Forward overhead is installed on the shell using FDS brackets. FWD overhead locks in closed position by two 1/4" bolts that I push through the fitting holes. For opening I just pull the bolts out while holding overhead front end with one hand.

It can swing down from the front to back.

For AFT overhead I had to vandalize those FDS brackets. :) Now AFT overhead swings down from back to front.

Opening AFT this way provides access through the sim roof to projectors. Two top shell roof panels are not installed.

For IRS Panel I use Phidgets 2-line TextLCD card.

Flaps indicator uses same LEDs as the rest of the sim. There were LEDs provided with AFT overhead kit, but I preferred my LEDs from Christmas lights. I installed them on small PCBs.

AFT overhead Audio panel is not used for audio purposes. I actually used the potentiometer on AFT Audio Panel to control the AFT overhead backlighting. One of the switches controls the cooling fan inside the overhead.