First panel test.

[Cfrisella]

Well into the process of wiring my panel up I'm really excited about lighting it up for the first testing. I'm also scared that something isn't wired correctly or in the wrong pin. My panel has dual GRT's, 430, SL30, EIS 4000, 327 and Garmin 240 audio panel all getting life from a VP 100. I've followed the schematics closely but I wish things were easier to understand. My question is, what kind of damage can occur if pins are in the wrong locations? What have people experienced the first time sending power to their panel. There's just a lot of connections and I sure I'll screw up at least a couple. It's my nature.

[Ironflight]

If you have any real doubt about having power pins connected corectly, I'd start with the connectors REMOVED from your expensive boxes. Pull all your circuit breakers, then power up the aircraft bus. Now push in breakers one at a time, and use a voltmeter to make sure that the correct pins have power. Check grounds as well. One you have assured yourself of this, power down, pull all the breakers, make the connections, and do the power up again - one box/breaker at a time.

No smoke? Great! Now it is time to see if all the boxes talk to each other - there is very little damage that can be done if the serial lines are wrong - except to your hair follicles as you rip them out one by one....

Paul

[MCA]

Chris,

Safest bet is to follow the installation manual -> use the test leads supplied with the wirnig harness and the correct size fuse to power on one device at a time. Then you can power up the system as a whole. Call if you have any questions.

Marc

[Ironflight]

Oops - I missed the part about the VP100. I still am a proponent of the cautious, "one box at a time" approach, but Marc is the expert on his electrical systems!

Paul

[Bob Axsom]

If you made up your wiring diagram/schematic using the manufacturer's pinouts (power, ground and signal names with respect to connector pins) and checked off the terminations as you wired everything you should have a lot of confidence in the configuration.

Sit down with your manuals and check the terminations on the airplane wiring diagram/schematic to make sure they meet the needs of the equipment as specified by the manufacturers.

Continuity check wiring especially the power and ground lines and discontinuity check to verify that power and signal lines are not shorted to ground. This needs to be done in a methodical way with accounting for all wires to be effective.

When you have assured that everything is OK as far as conformance to the manufacturer's requirements and your airplane wiring diagram/schematic you can turn everything off and progressively power up and work through a battery powered functional and limited performance checkout. You should write up a test plan and record your results as the checkout is completed.

A war story from the late 50s and early 60s. The first 5 Mercury Capsules were hand rung by inspectors working around the clock and each capsule took around three days to complete. In the beginning each capsule had around 3 thousand wires not including the escape tower and the retrograde pack and the number grew with each successive capsule. It was a stimulating task and we tried very hard not make any mistakes and we tried to complete more wire checks that the other shifts. We worked in teams of two with one inside the capsule making connections and reporting results and one outside calling off the connections and recording the results. The process was to check for continuity between two points on a checklist and then check from one of the points to ground. When the check was complete and all anomalies resolved power on checks could begin. I will never forget one day when I came to work in the white room and saw this large glob of molten copper hanging out of the hatch from the wire bundle at the Z123 ring - the result of a short. The company (McDonnell Aircraft) went to the expense of using large and expensive DITMCO machines after that for all continuity/discontinuity checking. The point is, be methodical and take your time.

Bob Axsom

[Cfrisella]

Thanks for all the responses. At this point it time it's still overwelming I think. The main power and ground leads to everything don't trouble me too much. It's just all the interconnecting serial (d-subs) and Arinc pins. Example, and I know this a no brainer but still.
My 430 and 327 came with a partical harness assembled by Pacific Coast avionics. Most of the connects to the 240 audio panel, Grts and SL30 were straight forward. After all loose connections were made I still had this one questioned. It comes off the 430 and is connected somewhere to the SL30. The heat shrinked label reads "430 Com Transmit interlock PTT on SL30". Looking at the SL30 pin descriptions I don't see anything reading "transmit interlock". There's a pin I wanted to guess at that sounded like it could be a home but I started to shake and left it alone for the time. I wanted to connect that pin to the SL 30 at pin 4 (transmit enable key).

[jetjok]

Bob,
If we ever meet, I will buy you as much food and libations as you would like, if I can hear more about working in the early days of the space program!
Building the Mercury capsules!...How cool is that?!

Originally Posted by Bob Axsom

A war story from the late 50s and early 60s. The first 5 Mercury Capsules were hand rung by inspectors working around the clock and each capsule took around three days to complete. In the beginning each capsule had around 3 thousand wires not including the escape tower and the retrograde pack and the number grew with each successive capsule. It was a stimulating task and we tried very hard not make any mistakes and we tried to complete more wire checks that the other shifts. We worked in teams of two with one inside the capsule making connections and reporting results and one outside calling off the connections and recording the results. The process was to check for continuity between two points on a checklist and then check from one of the points to ground. When the check was complete and all anomalies resolved power on checks could begin. I will never forget one day when I came to work in the white room and saw this large glob of molten copper hanging out of the hatch from the wire bundle at the Z123 ring - the result of a short. The company (McDonnell Aircraft) went to the expense of using large and expensive DITMCO machines after that for all continuity/discontinuity checking. The point is, be methodical and take your time.

Bob Axsom

[az_gila]

...but clearly mark each connector in the harness for the location of pin 1.

Make sure the reference picture you work from is viewed from the same direction as you do the marking.
There are usually two possibilities, and that Irishman Murphy often crops up and picks the wrong one....

A high power magnifying glass and a strong light can also be used to read the actual pin numbers on the connector.

I have seen more than a few cases of professional assemblers (and draftsmen) assuming the wrong pin 1...

[Ironflight]

Originally Posted by Cfrisella

Thanks for all the responses. At this point it time it's still overwelming I think. The main power and ground leads to everything don't trouble me too much. It's just all the interconnecting serial (d-subs) and Arinc pins. Example, and I know this a no brainer but still.
My 430 and 327 came with a partical harness assembled by Pacific Coast avionics. Most of the connects to the 240 audio panel, Grts and SL30 were straight forward. After all loose connections were made I still had this one questioned. It comes off the 430 and is connected somewhere to the SL30. The heat shrinked label reads "430 Com Transmit interlock PTT on SL30". Looking at the SL30 pin descriptions I don't see anything reading "transmit interlock". There's a pin I wanted to guess at that sounded like it could be a home but I started to shake and left it alone for the time. I wanted to connect that pin to the SL 30 at pin 4 (transmit enable key).

The good news is that if you are confident that the power and grounds are OK, then you really can't do much damage by having signal pins messed up - except, as I mentioned before, to your hair as you slowly pull it out, looking for what didn't get matched properly. And that is simply a matter of patience.

Paul

[az_gila]

Originally Posted by Cfrisella

..... After all loose connections were made I still had this one questioned. It comes off the 430 and is connected somewhere to the SL30. The heat shrinked label reads "430 Com Transmit interlock PTT on SL30". Looking at the SL30 pin descriptions I don't see anything reading "transmit interlock". There's a pin I wanted to guess at that sounded like it could be a home but I started to shake and left it alone for the time. I wanted to connect that pin to the SL 30 at pin 4 (transmit enable key).

...pin 4 is the PTT input for your Comm 2 (I presume Comm 1 is the 430).

Since you have a real audio panel, the 240, the SL-30 pin 4 should connect to a pin on the 240 called something like (Com 2 KEY__) - that is the pin name on a Garmin 340 - the 240 should be similar.

Your true audio panel performs the "TX Interlock" function.

If I made the wrong assumption about Comm 1, no big deal, just reverse 1 and 2 on the audio pin names...