Show me your Wiring Diagrams

[Watzlavick]

If you are interested in going with Gigavac (your part number indicates, you are) order early mine was back ordered for 6 months, and it is a more common contactor.

I received them but yeah, it took forever.
-Bob

 

[rogerabc]

Why do both trim servos share the same cb?
Surely you wouldn't want an aileron trim fault to take out your pitch trim servo.

 

[N890GF]

Why do both trim servos share the same cb?
Surely you wouldn't want an aileron trim fault to take out your pitch trim servo.

Not exactly sure which post you're replying to, but in my specific case, I wired my trim motors (roll and pitch) through the Dynon AP panel module. It acts as a stand-alone trim controller. Power input to the panel module has a separate 5A CB for trim control, and then the panel handles each servo separately. I think Garmin has a similar situation with its trim integration, but I don't know the details.

 

[sblack]

Why do both trim servos share the same cb?
Surely you wouldn't want an aileron trim fault to take out your pitch trim servo.

It would take more than a trim fault. It would probably take a dead short. Pretty unlikely. Not impossible, but neither is landing with no trim. That was my logic on mine.

 

[Watzlavick]

Why do both trim servos share the same cb?
Surely you wouldn't want an aileron trim fault to take out your pitch trim servo.

I wired up the trim servos the same way the A/P servos are, both to a single CB. I didn't want to add any more CBs than needed. In a Garmin system, if the pitch and roll A/P servos have power (even if the A/P is not engaged), trim power is supplied by the GSA 28 servos using PWM for trim servo speed scheduling. The separate trim power inputs to the GAD 27 are only used if there is a GSA 28 fault or the CB is pulled for the A/P servos. So in a runaway trim situation, you really have to pull two breakers, the pitch/roll A/P CB and the pitch/roll trim CB. At least that's the way I understand it.

-Bob

 

[Walt]

I wired up the trim servos the same way the A/P servos are, both to a single CB. I didn't want to add any more CBs than needed. In a Garmin system, if the pitch and roll A/P servos have power (even if the A/P is not engaged), trim power is supplied by the GSA 28 servos using PWM for trim servo speed scheduling. The separate trim power inputs to the GAD 27 are only used if there is a GSA 28 fault or the CB is pulled for the A/P servos. So in a runaway trim situation, you really have to pull two breakers, the pitch/roll A/P CB and the pitch/roll trim CB. At least that's the way I understand it.

-Bob

Not quite right, trim power is from the trim CB, the AP servos either pass it thru (if not powered) or speed schedule when they are powered, but Trim power is always from trim CB. The GAD27 is just a fancy trim relay.

 

[Watzlavick]

Not quite right, trim power is from the trim CB, the AP servos either pass it thru (if not powered) or speed schedule when they are powered, but Trim power is always from trim CB. The GAD27 is just a fancy trim relay.

I was going off the information from this post from g3xpert:

Connecting Garmin GAD 27, GSA 28, and trim

Looking for info on how to power the GSA 28 AP servos and trim when you have the GAD 27. The GAD 27 shows connecting the trim through it, but what about the GSA 28 servos, they also show connecting the trim to them. The GAD 27 install information makes no mention of the GSA 28 AP servos. I have...

vansairforce.net

One thing to remember is that the trim motor(s) are rarely powered by the GAD 27.

In normal operation the GSA 28 servos are always powered-up, and even when the autopilot is disengaged, the servos are providing speed scheduled variable voltage to the trim motors independent of the GAD 27. The GAD 27 is only providing trim direction signals to pins 11,12 of the GSA 28 the majority of the time.

It is only when the GSA 28 is powered off (a trim bypass relay drops) and non speed scheduled direct drive power is being supplied by the GAD 27 to the trim motor does the size of the GAD 27 trim power circuit breaker make any difference.

This post is also relevant:

Garmin GAD 27 Electricity Flow (trim)

I'm working on wiring for the Garmin GAD 27 and have some questions about how power goes in and out related to the trim servos. First, some basics. There are two power inputs so the GAD 27 can be powered from two separate busses -- J271 pin 7 and TB273 pin 1. Technically the latter is for the...

vansairforce.net

In a complete airplane (not me yet), you could test this by pulling the trim power CB to the GAD 27 and see if the GSA 28 still controls the trim servos.

-Bob

 

[Walt]

I was going off the information from this post from g3xpert:

Connecting Garmin GAD 27, GSA 28, and trim

Looking for info on how to power the GSA 28 AP servos and trim when you have the GAD 27. The GAD 27 shows connecting the trim through it, but what about the GSA 28 servos, they also show connecting the trim to them. The GAD 27 install information makes no mention of the GSA 28 AP servos. I have...

vansairforce.net

This post is also relevant:

Garmin GAD 27 Electricity Flow (trim)

I'm working on wiring for the Garmin GAD 27 and have some questions about how power goes in and out related to the trim servos. First, some basics. There are two power inputs so the GAD 27 can be powered from two separate busses -- J271 pin 7 and TB273 pin 1. Technically the latter is for the...

vansairforce.net

In a complete airplane (not me yet), you could test this by pulling the trim power CB to the GAD 27 and see if the GSA 28 still controls the trim servos.

-Bob

Sorry I was thinking normal trim operation, auto trim is powered by the servo breaker.