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Older MAC servo wiring diagram needed

S

sblack

Well Known Member
My project came with a 90s vintage MAC servo. It has 2 white wires, 2 orange striped wires and a green striped wire. This is different than the newer RAC units. Anyone have a wiring diagram for one of these? I tried the ray allen site.

I tried putting a 9v battery across the 2 white wires but it didn't work. I guess I need to RTFM.
 
sblack said:
I tried putting a 9v battery across the 2 white wires but it didn't work. I guess I need to RTFM.
Click to expand...

Did you try reversing the wires----------I suspect the whites are the motor---- the polarity is reversed to drive the motor the other way.
 
If you aren't in a hurry, I have one, including the manual, at home. But, I'm away for a couple of weeks. I can look it up when I return.

I used a 14V battery from my power tools and it works with the two white wires. Yes, by reversing the wires it reverses the direction.

Off the top of my head, I believe the other wires had to do with the position sensor.

Best,
Jerry Folkerts
 
MAC Wiring Diagram

Scott -

I found my wiring diagram from MAC (Menzimer Aircraft Components) from 1991 and it confirms that the white wires are for the servo motor itself; and, the striped wires are for the position indicator (if installed).

The wiring instructions are three pages long. I am happy to copy what I have and send it to you via snail mail if you'd like.

Just let me know.

OBTW - I also have an NOS MAC 4A Servo with the exact same wiring as yours - 2 whites, 2 striped orange & 1 striped green. It was an extra that never got installed in my Rocket back in the 90's.

Send me your mailing info if you would like a copy.

Thx

David Howe
 
Ok that's what I thought. I tried the white wires both ways. I guess that means my servo is dead. :mad:

Thanks anyway.
 
MAC 4A Servo

Scott -

If you need a replacement 4A servo, I have a NOS unit I will sell at a very reasonable price. I'll donate the entire amount to this site - a wonderful resource we should all support.

David
 
Just a comment.

Even if this is a new motor that has been setting around far a long time, it does not mean it is dead right off the bat. We have had to wake-up many ( d.C. ) motors that have been asleep for a long time down through the years.
The brushes and armature will have oxidation between them and not make good contact if they have not been run a little now and then. If there is no electrical fault in the unit other than this contact area of the brush and armature, most of the time you can just turn the armature by hand or all and scrub some of that crud off the armature. If it starts running, then run it back and forth tell the brushes take a new good seat. I have had to do this with many new starters and fan motors as well as some old ones that have been laying asleep for a long time. But a new one may make you feel better about this application, its your call. If you are going to get a new one, don't be afraid to take the cove off the old one and try this out. You may like what you can do. Yours as always, R.E.A. III #80888
 
correct, the two white wires are the motor wires. the other three are the indicator pot wires, if I remember correctly it is a 5k pot. i do not remember which are the ends and which is the wiper, but that is easy to figure out with an ohm meter.

bob burns
RV-4 N82RB
 
I took the cover off and spun the motor and it works fine now! :D Thanks for the tip. Saved me $150!
 
n82rb said:
correct, the two white wires are the motor wires. the other three are the indicator pot wires, if I remember correctly it is a 5k pot. i do not remember which are the ends and which is the wiper, but that is easy to figure out with an ohm meter.

bob burns
RV-4 N82RB
Click to expand...

I don't think the old one has a pot. It has some sort of funky indicator with 3 bulbs to indicate movement but not position. I might kluge up a pot installation.
 
The old ones used a 3 LED indicator Left/Center/Right. Was using the shut off micro switches for the motor stops. Make sure those micro switches are cleaned with a little spray. If they fail it could strip a gear.
 
You guy are talking really old, mine from the early 90's were pot type.

Bob burns
Rv-4
N82rb
 
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