FSBUS Noice/Interference HELP !?

[Guest olly]

Hi! I was connecting the FSBUS Interface modules of the 737NG Pedestal today and was DISAPPOINTED! Have the COM board behind he MIP and 2xDisplay/1xLED/1xKEY inside the pedestal box. The cable connecting the pedestal interfaces with the COM board is shielded and I have connected the shield to ground on the COM side. All other cables are ordinary flat-cable. Problem is that there seemes to be lots of electrical noice in the "system" when I connect the bus cable (approx. 1.8m long) connecting the COM and the pedestal interface boards.. Have another FSBUS Key interface in the MIP section and that seemes to be affected too (the test function shows lotsa quick signal changes)! In addition the relatively short cables from buttons/rotaries to the Key board (both are inside the pedestal box) creates lots of "noice" also (in the test function for the pedestal Key board typically turning any rotary will generate on/off signals for all buttons in that row. The Key Interfaces are CID 1 and 2. All in all a big disappointment!! Question is: Is there anything to do to fix this ?? What Interface solution are you guys using and have you had the same noice problems ? Please dont tell me all the interface work/expences was in wain and that I have to go for a different solution.....Ole..http://www.almenningen.no/cockpit

[Guest bowingic]

Hi OleI can't really offer solutions to your problems but just pass on my own experience with FSbus configured in a similar way to yours.The only problem I'm experiencing is the occasional switching on of something I'm not expecting...eg I switch in the overhead window with a switch.....occasionally it might appear on its own but not frequent enough to be a major problem....of course a fuel control switch might be a different matter but one can always treat that as an unexpected engine failure!! I assume such events are probably interference of some kind. I use all flat cables....the FSCOM to FSKEY cable is about 1.5m long.A first step in fault finding would be to isolate all FSbus equipment away from monitors, power supplies etc. and see if that changes anything. I found a battery charger in the same room was enough to seriously interfere with my FMC TV display. Probably telling you how to suck eggs as they say....but just trying to help. Also just set up one FSkey board with all other Fsbus boards removed and see if the problem still exists.I would appreciate if others with more experience with FSbus than myself to input here to see how others systems are functioning in this regard.

[Guest perchas]

Hi Ole,The problem is more complex. The systems we used, Fsbus, Iocards, Epic, Pidges etc are designed as if they were a single printed circuit, example: let

[tigert]

Yep, try shorter cables, try with only one module, then add one by one, see if you can isolate the problem to a particular module?Also I think there was some comments about what CIDs can be used with each module (I dont remember now, maybe Dirk or someone who remembers can reply?)Also, 99.999% of the problems people have seem to be caused by short circuits or cold solders or tiny droplets of solder shorting something on the boards.So, see if it is a particular module that causes this? I dont have anything like you describe either, but I have occasional odd things like Ian describes. Not very frequently though, more rare than common.//Tuomas

[tigert]

For the record, I drive my FSBUS at 12V from the PC power supply. I just have a heatsink on the voltage regulator in the COM-card (which is a good idea to have anyway)//Tuomas

[Guest perchas]

I have modified the power supply of the COMIII, once recorded all PIC disconect the power of 9 VDC, and coneect 5.8 VDC to out of the regulator 7805, I use an exclusive power supply of great quality with adapted filters and cable shields, I do not use PC power supply.SaludosRafaelhttp://forums.avsim.net/user_files/104149.jpghttp://forums.avsim.net/user_files/104150.jpg

[Guest GusB]

I

[tigert]

>Also, as a side note... increasing the input supply,>beyond a certain point, to the 7805 is counterproductive as it>will only make the regulator run hotter, which will require a>larger heat sink because of the additional power being>dissipated.Good information everybody, thanks, interesting to me as well.The reason I mentioned the 12V was not to say it is "better", I just wanted to shed a bit of light on my own setup where I dont have too much trouble. I did have issues with the servo card though, it would give interference a lot, but I suspect my soldering there.We had trouble at the Malmi Aviation Club sim (the Cessna cockpit you have seen, linked from www.simkits.com builders section for example) where we would have speaker wires go next to FSBUS stuff and power cables - those were just asking for trouble so we re-routed stuff a bit farther away from each other.//Tuomas

[Guest GeorgeDorkofikis]

Just a thought... But before I analyse it...Do you have any PhaseShift Rotary encoders and REDEC (or similar) circuits connected to your FSKEY cards ?If so, HOW have you connected the redec outputs?George DorkofikisAthens, Greece

[Guest olly]

The problem was fixed the next morning (no, no sleep in between..)!Was a faulty 24V powersupply that made all the interference. Even when moved away approx. 4meters it still made the FSBUS Keyinterfaces send lotsa rubbish to the COM card. The faulty PS is now.. very much in the bin :)Forgot about the forum postings about it, and here I find lotsa interesting info from dedicated and helpful builders.All the tips about raising the voltage etc. have been noted.What a great community this is!Thanks gyus!All the best,Ole J. Almenningenhttp://www.737cockpit.no