A rare piece for my sim

[Michael Carter]

Just picked this up from my regular e-Bay Boeing supplier:

http://i63.photobucket.com/albums/h146/boeing722/SP50.jpg

I can't wait to get this on the bench and open it up. The paddle switches are solenoid held when engaged in the aileron and elevator hold modes. If they are 115vac and 400 Hz I'll have to change them out for something more conventional.

I can't wait to push the AP release switch and watch the paddles disengage.

It'll be some work, but it shouldn't be too dificult to get it integrated into the sim.

These are rare, rare, rare on the open consumer market. I've only seen one other in three years and it was not quite the same model. It was the MB-V. This one is the MB-IV, and though older, is the correct auto pilot for my build.

[jmig]

Show a little excitement. No need to be so oh-hummm. LOL Congratulations on your coup. Isn’t his hobby awesome!

[Michael Carter]

Yep, I'm pretty excited about it. I've been waiting a long time for this part. I have one that I built that functions just fine (except for the solenoid-held paddles) in the sim, but it's just not the same as the real deal.

Besides, mine doesn't have a working light plate or the correct knobs.

[Gsey]

How did you get on with the solenoid paddles? Are they just a 28v coil like other magnetically held switches? I hope so. If they are you might be interested to know that the 28v type can hold position with only 12v applied.

Gary

[Michael Carter]

After looking through my systems manual, they are indeed 28VDC solenoids.

They are powered from the 28VDC Essential Radio Buss.

This might be a walk in the park after all. :D

[Michael Carter]

It's even better than the e-Bay photo shows. Just a little paint wear on the BIG knob. Still has all the paperwork and tags attached to the top of the chassis case and was working when removed.

http://i63.photobucket.com/albums/h146/boeing722/SP501.jpg

I can't imagine what this unit cost new.

Now the fun begins tracing the pin-outs on two 54 pin jacks on the back of the chassis!

The great thing is that my home-built using was spot on for measurements that I interpolated from almost half-scale drawings from Delta. It will slide right in to the center control stand with no other modification.

Most of my other real panels that replaced the scratch-built units were off by as much as 3mm and created some problems in the overhead, but eventually I got them to fit properly.

Life is good!

[Michael Carter]

After taking the unit apart and checking the light plate, I moved to the solenoid held paddle switches.

Here, the 28VDC solenoid is energized allowing operation of the paddle switch to the engaged position and is being held in the on position by the solenoid.

The microswitches (pictured in front of the yellow solenoid coil with the wire bundle) are depressed and I found continuity on two pins on the large square circuit card ajacent to the solenoid.

This assembly is only one switch. A marvel of electro-mechanical engineering. I wish you could see this in person. It really is amazing how this is designed.

Sorry for the photo quality.

http://i63.photobucket.com/albums/h146/boeing722/SP504.jpg

[Michael Carter]

I've figured out the mode control switch now. That switch is also spring loaded, but uses an electro-magnet instead of a solenoid to hold the switch in position while power is applied.

Fascinating piece of equipment.