Electric Trim Drawing

[katzhome]

Thank you all.  I'm still digging through the manuals and the plane.  I'm now getting some of the wire IDs to match the diagrams.

 

From the Century manual:

 

Looks like the more appropriate diagram is the 4a diagram on following page:

 

 

And from squeezing myself under the pilot's yoke:

 

The servo in the aft bay ID doesn't seem to match, but I'm still investigating.

Actually, there is CD-45! It's upstream of the CD-73 line that goes into the servo.

 

So does anyone know where the relay box resides?  I did not find anything looking like that while under the panel today.

 

 

[EricJ]

Sounds like you're making progress.    One of the things I did to try to narrow down to the appropriate drawing was match the trim amplifier model number, so make sure yours is 79C53 before going too far.

My relay box was under the panel.   The Century III with the pitch trim and glide slope coupler has a large number of little boxes scattered under the panel and in the tail, so it is a little tricky at first to find everything.   It's also why they're difficult to fix when they break, because there is essentially zero on-board diagnostics and the same signal may flow through three boxes before it gets somewhere useful, and any one of them has an opportunity to corrupt it.   Fault isolation is difficult.    I eventually gave up, but would like to keep the trim system if needed when the next autopilot gets installed, whatever that may be.

A flexible USB endoscope or at least a mechanic's mirror on a stick might be useful to find the labels on the little boxes under the panel.   In my airplane they're just randomly mounted in odd orientations to apparently whatever space they could find for them at the time, and identifying each was sometimes challenging.

[katzhome]

Of course more study may show that things are as simple as this, but I have more tracing and probably some continuity checks to do.

 

[N201MKTurbo]

8 hours ago, katzhome said:

Thank you all.  I'm still digging through the manuals and the plane.  I'm now getting some of the wire IDs to match the diagrams.

 

From the Century manual:

 

Looks like the more appropriate diagram is the 4a diagram on following page:

 

 

And from squeezing myself under the pilot's yoke:

 

The servo in the aft bay ID doesn't seem to match, but I'm still investigating.

Actually, there is CD-45! It's upstream of the CD-73 line that goes into the servo.

 

So does anyone know where the relay box resides?  I did not find anything looking like that while under the panel today.

 

 

The relay box is on the firewall right below the vacuum regulator.

[bradp]

I have a working when removed trim motor and relay is sitting on my shelf that I can part with if needed. 
 

b