G5 HSI Installation and 1c388M AutoPilot

[KyleG]

HI all,

I'm trying to finish up a G5 HSI install and thought I would post a few notes. Looking for some help and hope to give others some help. I have to give a big thank you to @bradp He has really gone the extra mile with the century AP wiring and parts list for me. 

I contacted my local friend who is an A&P AI and he decided to supervise me with this install. Truth be told he did at least 60% of the work and told me what to do. Because every install is different he was stumped on a few things, as was I. The interfacing of the Century Auto pilot to the Gad29B is not the clearest I feel. 

Dealing with many  transformers, resistors, inductors and capacitor seems to be a bit confusing to me. 

The G5, Gad29b, and the magnetometer where straight forward as my supervising AI has done a few of them already. The issue has been with the AP interfacing which i'm still having issues with.

I had to take the Garmin diagram attached and lay it out with him. We then made a drawing of  everything and followed in to detail. I also leaned on @bradp for this.

The biggest question or confusion is the polarity of the resistors and tank circuit. There was no label in regards to the direction the circuits needed to be interfaced. Note 3 on diagram and Note 4. 

After the install and G5 Flight Control setup we went for a test fly. "Nothing" happened. Wing leveler work as normal. But Radio coupler does not pick up the heading bug on the G5. 

I hope to pull this wire harness apart this week and find the gremlin causing this issue.

[OR75]

if you read the PDS of those components, you will see that the are not polarized 

 

[KyleG]

I spent the evening trouble shooting the interface harness. To be sure it was not a AutoPilot  error, I hooked up the old DG directly to the CD-33 Female plug with the current new harness spliced in. (I had the new harness completely unhooked and isolated) This by passes the Radio coupler completely.

I ran the plane up and turned on leveler... All good. Turned on HDG and moved the old DG heading bug to the left... it checked out.... moved it to the right and it checked out. No issues with the old system.

It has to be the in the new wire interface. I really did not want to pull it apart but had to. I did all continuity checks and ground checks to make sure there where no shorts. I pulled apart the D-sub to the Gad29B and went to do my continuity check when I found Pin 14 was not seated all the way. (I'm embarrassed to say this)

I pushed the pin in and temporarily put everything back together. Turn on plane and did ground check again.

When the G5 Loads up and I turn on the wing leveler now if follows the heading bug no problem. This is great but sure is not right as I do not have the HGD selected on the AMP. I'm glad the interface harness is talking with everything but I still can't figure out the issue here.

The only other test I can think of doing is removing the pigtail connection and putting back on my old DG for a Radio Coupler check. The other test I think I'll run tomorrow is turning off my nav radio while doing the test to see if there is any interference. 

I'm still not sure why the system goes hard left when I turn on the HGD switch yet follows the bug under wings level configuration. 

If anyone has any trouble shooting idea I'm all ears. Thanks for the help!

[Stanton R]

Rather then use all the transformers, capacitors and inductors we use the AIU 900A from Deklintech. It is only $250 and you end up with a much nicer installation.

 

You also want to turn on GPS steering unless you are not hooking it up to a GPS

 

http://www.deklintech.com/assets/aiu900-install-manual-rev-2.0.pdf

[KyleG]

Follow up to this thread.

on 6-7-2019 I put everything back together. Did my ground check and had the same issues but they were not as prominent as before. (Maybe the shield grounds having better continuity to the aircraft frame helped)

Anyways I did my full ground check and then turned off my G5 and reprogrammed it to the Century A/P setting instead of the AutoControl setting the G5 has. Bingo!!! It works perfect now!

Flew it down to Avionics shop on Monday after putting 3 hours on it this weekend. I Love this G5 interfaced to the A/P 

Can't wait for the GNX 375

 

[JDP]

I see you have a radio coupler in your plane. I don't have one on mine. Not sure how to make the connections without the radio coupler any help would be great.

[jamesm]

Nice job on your layout... I guess it never occurred to me  having the  hand drawing and  the schematic drawn like you have done.  My method involves having multiple copies and  a lot page flipping  and some where in the process losing one copy  or forgot print the  copy that I needed at least  once  so then I have go print the copy again.

[carusoam]

Welcome aboard JDP!

Lets see if @KyleG is stopping by...

Best regards,

-a-

[Jake@BevanAviation]

9 hours ago, JDP said:

I see you have a radio coupler in your plane. I don't have one on mine. Not sure how to make the connections without the radio coupler any help would be great.

@JDPWithout a radio coupler you just wire per the print to the DG connector CD33.  You can get a pre-made isolation box like the AIU-900D from Deklin Technologies that will help with the interface.  See attached print for interconnect of a Century II.  NOTE: without a radio coupler the G5 HSI will only function as a DG with the option of GPSS.

Century IIB pin out.pdf

[AV8R-IA]

Thanks for the post. I’m trying to do the same, can you post the parts list so I can do it. I’m having difficulty finding the connector for the pigtail.

[OR75]

10 hours ago, AV8R-IA said:

Thanks for the post. I’m trying to do the same, can you post the parts list so I can do it. I’m having difficulty finding the connector for the pigtail.

the connectors for the pigtail are Amphenol 126-198 (or WPI)

do an internet search for Amphenol 126-198 and you will eventualy get to the right part number for male/female and number of pins.

I have a pdf catalog of those connectors.  

[AV8R-IA]

Thanks very much for the p/n for that connector.

[OR75]

16 minutes ago, AV8R-IA said:

Thanks very much for the p/n for that connector.

 

126-Series-Miniature-Hexagonal-Connectors.pdf

[ijs12fly]

@KyleG  @Jake@BevanAviation

Kyle - Do you ever put your Radio Coupler in any other mode besides HDG?  Like: NAV, OMNI, LOC NORM, LOC REV?  Would there every be a reason to do so?

Do you know what model RC you have - 1C388M,  or 1C388-2 (or -3)?   

I am doing a similar install (GNX-375, G5 and have the 1C388M, but shop has concerns with that coupler acting correctly for the HSI and all modes working correctly on the RC.  So he is working with me to try to find a -2, or -3.  

Other challenge is I have older "analog" NAV/COMS MX170B.  So I believe that keeps me from mixing new with old, and old will no longer work with autopilot.

Thanks

Steve

 

 

 

Edited April 9, 2022 by ijs12fly

[jamesm]

Didn't Garmin come out with GAD29D i think is it's destination for this purpose of analog autopilot connectivity with the G5?

[Bruno Eduardo]

On 12/4/2020 at 9:42 AM, Jake@BevanAviation said:

@JDPWithout a radio coupler you just wire per the print to the DG connector CD33.  You can get a pre-made isolation box like the AIU-900D from Deklin Technologies that will help with the interface.  See attached print for interconnect of a Century II.  NOTE: without a radio coupler the G5 HSI will only function as a DG with the option of GPSS.

Century IIB pin out.pdfUnavailable

Is it possible to resend this file, I need to make this one in a aircraft. Please.

[OR75]

On 4/9/2022 at 8:26 AM, ijs12fly said:

@KyleG  @Jake@BevanAviation

Kyle - Do you ever put your Radio Coupler in any other mode besides HDG?  Like: NAV, OMNI, LOC NORM, LOC REV?  Would there every be a reason to do so?

Do you know what model RC you have - 1C388M,  or 1C388-2 (or -3)?   

I am doing a similar install (GNX-375, G5 and have the 1C388M, but shop has concerns with that coupler acting correctly for the HSI and all modes working correctly on the RC.  So he is working with me to try to find a -2, or -3.  

Other challenge is I have older "analog" NAV/COMS MX170B.  So I believe that keeps me from mixing new with old, and old will no longer work with autopilot.

Thanks

Steve

 

 

 

old question but the G5 HSI works great with the 1C388M

you need to be in LOC mode for an ILS approach 

agree that NAV and Omni modes are not as useful since a VOR station is also GPS Waypoint so GPSS would work just as well