First power up of the electrical system

[flyvans.com]

Hi,

just wanted to let everybody know that power was successfully applied to the electrical system of HB-YMT yesterday
And there was no smoke ;-)

Setting up and configuring the Vertical Power VP200 was a joy, and having planned and installed everything according the master wiring excel sheet things went well at the first attempt!

Here's what i've found, some are easy fixes, others require some troubleshooting

- the aoa sport display is mounted upside down.
duh. simple fix. however, when looking into the leds, what looks greenish / yellowish unlighted and makes you install it, turns out the other color when powered. should have strictly stuck to the manual and not even looked at which color it could be....

aoa volume too low
all the external audio too low? will have to figure out wheter i have to adjust just the aoa audio volume pot or the unswitched input level on the GMA-340.
should be an easy fix, though.

trutrak pitch servo inverted direction
easy fix, just need to cut the reverse direction loop in the harness.

icom200 backlight
we had the backlight wired to a dimmer circuit together with the panel light. however, the backlight really should be always on during operation, so we'll change it to a always on 12v pin.

white noise
this is the biggie... maybe somebody has been there / can help trace it?
- audio panel: GMA-340, original harness professionally prepared by steinair.
- headset and mike plugs isolated from the panel.
- everything audio grounded at the same point.
- when powering up even only the electrical system and the audio panel, i get a lot of white noise. it definitely isn't interference from other units. if i additionally power up the radios etc... there is no change.
- the noise does adjust volume with the volume knob on the intercom.
same with different headsets (DC and QT Halo)
- if i select ICS ISOL CREW it gets much better, and with ICS ISOL PILOT even a tiny bit better. however still annoying. probably won't be heard over the engine noise, but we'd like clear audio nonetheless! no unnecessary strain on the ears.
- one passenger headphone wired to a jack to be used for recording on camera etc... would hate to give that up because of a wiring/noise issue.
- all other settings on the audio panel do not affect the noise.
- high music gain option is wired in the harness.
- unswitched audio is tied to an ap-60 mixer (however noise still is there no matter wheter the ap-60 is powered or not)
anybody know where to start?

distortion when transmitting on com1 (sl30)
when transmitting on com1 (SL30), at least the sidetone in the headset sounds very distorted. don't know about the transmission quality yet, have to test that. interesting that this isn't the same problem with the com2 (icom200).
could also come from testing in a rather small indoor workshop over the comant belly mounted bent-whip?

lcd backlight noise
there is very little but noticeable and annoying high-pitch noise in the audio from the lcd backlight of the vp200 display unit. it changes depending on screen brightness selected. possible reason could be that it's right beside the radio stack.

still waiting for the advanced efis's, so no experience wheter our wiring works as intended... it's ready for plug&play.
also the mappc parts were not fitted for this test yet.

rgds,
bernie

 

[MCA]

Bernie, You can adjust the SL-30 sidetone volume level in the SL-30 setup screens.

 

[scard]

Could the white noise be coming from RF in the local environment? Assuming you're in an enclosed shop (not where an airplane is normally operated). Lights and other equipment in the shop can cause all kinds of noise.

 

[L.Adamson]

Are you using a 12 volt power supply, other than a battery? If so, it can add a lot of noise.

L.Adamson --- RV6A

 

[flyvans.com]

update

hi everyone,

thanks for all the advice...

just to let you know, i've made significant progress...

almost all of the white noise, display background noise etc... issues are now gone.
looked at the isolation washers / headset&mike plugs again. turns out, all 4 holes in the panel were slightly undersize and at least one plug made a bad local ground. make sure you measure/drill the holes to the outside diameter of the plastic washer and not based on the plug itself.

now i'm still hunting two issues:

- bad sidetone when transmitting on the sl-30.
it has gotten a bit better after playing with the mic gain and sidetone level settings, but i'm not quite there yet. funny as the icom200 com2 works just fine without altering any settings.
anyone care to post their SL-30 settings used in conjunction with a garmin gma-340?
will

- way too low volume level of the various audio sources wired through an ap-60 line mixer.
i wired the ap-60 to pins 31 and 32 on J1 ("alt warn", unswitched, unmuted radio input as per garmin install manual)
the gma-340 install manual doesn't mention any difference in the type of signal compared to e.g. a switched input such as adf or com3. therefore i doubt this would make it work.
anyone using an ap-60 in conjunction with a gma-340? how did you wire it?

thanks a lot for replies regarding the 2 open issues.

regards, bernie

 

[flyvans.com]

success!!!

hi,
thanks to all the support and suggestions i've received.

here's an update:

aux audio / display backlight noise / aoa volume / other noise: FIXED
the last biggie was the very very weak unmuted, unswitched audio in with all the warnings from other units through an ap-60 mixer.
turns out it was a really easy fix, only the polarity of the unswitched input was mixed up due to a labeling/wire color issue.
not only fixed it the aux volume but also got rid of most of the remaining noise (except some white noise which remains there but is very acceptable)

in the process, a good hint that i've gotten is to hook up the aux sender directly to an aviation headset and check wheter volume is ok (quality doesn't need to be).
if the volume is too low, the fix needs to be on the aux sender side. if the volume is ok, the fix needs to be on the intercom settings/wiring side.

icom200 backlight wiring: CHANGED
wired the backlight wiring directly to the icom power supply wire. now it's on anytime the icom is turned on. however should the lighting create a fault which is already unlikely, we'll loose com2. no big deal.

autopilot pitch servo direction: FIXED
simple fix, just cut the loop that's intended for this at the connector.

SL-30 bad sidetone when transmitting: 99% FIXED
had a real bad squeal when transmitting on the SL-30.
the fix lies in the config pages / system settings.
mic gain in the 40-50 region and sidetone level around 80 gave us comparable performance to the icom200, which worked like a charm out of the box. still like the general icom200 sound better though, but the SL-30 is definitely working as it should.

autopilot pitches down when transmitting on com1: NEW PROBLEM :-(
will have to get one of the filters for the db25 connector to the trutrak, hope it will fix it as in most cases that have had this exact same problem.

and by the way, we're using a 21A rated ground power supply ("Sunpower" SPS-320-P15) that simulates the alternator hooked up to the battery. has absolutely no impact on noise and lets us run the electrical system as long as we want

now, standing by for the afs efis'. hoping they will work out of the box and the wiring mix was a single mistake ;-)

rgds,
bernie