fxc 12000? good or bad?

[BadDog 0]

Especially when I'm flying home rather than driving.
CorporateLawyerDave aka BadDog

[BadDog 0]

And why would spell check on dropzone.com kick out Cypres????
CorporateLawyerDave aka BadDog

[Kirils 1]

The Astra has a clear cover over the off-on switch. I've never had a problem.
Skydiving is not a static excercise with discrete predictability...

[alan 1]

First some history:
The original FXC was developed by HI-TEK Corporation, and then further developed and produced by FXC Corporation, both out of California. Parachutes de France later produced the FXC 12000 on license from FXC Corp. The American model was found to have some weaknesses that caused it to
fire when it was not supposed to. This was, among other things, caused by leaks in an air hose inside the unit. PdF has developed the unit further and improved the quality of that air hose's attachment points. In 1994 the FXC Corporation recommended that all FXC 12000s should be updated to J-standard aka J-mod. This modification included more air filters for a "safer" and steadier inflow of air. Units that have gone through this modification have three gold colored filters on the control unit that allow air to flow into it. Only units that have been updated to J-standard have these filters.
Some data for the FXC:
Accuracy: 0-1800ft: -100ft / +300ft
1800-3500ft: -200ft / +400ft
Note: The accuracy is no longer acceptable at DZs that are at an elevation such that the firing altitude is above 3500ft. The manufacturer can calibrate the units to be appropriate for these altitudes, but non-calibrated units will not be.
Firing parameters: None at speeds below 40ft/sec
Possible at speeds above 40ft/sec
Effective at speeds above 65ft/sec
Altitude setting/re-cocking:
The manufacturer recommends that the main canopy is deployed at least 1500ft above the set firing altitude for the unit. The jumper should be under a fully opened canopy at least 1000ft above the set firing altitude. This is done to allow the pressure within the two internal chambers to equalize with the outside pressure before reaching the set firing altitude. If the chambers don't have time to equalize before the set firing altitude the right chamber will have a higher pressure than
the left one as an air hose inside opens. When this occurs a membrane will either move enough to cause the unit to fire, or just enough for the locking pins to move slightly, which can
cause a misfire on later jumps. The same can to a certain degree happen if the jumper engages in "sharp" turns while under canopy. The FXC must be re-cocked if there is a suspicion of a "near-fire". It is not enough to just recalibrate it. To re-cock the unit it must be removed from the rig! The unit should be in JUMP mode while doing this. Since it has to be removed from the rig, I'd strongly recommend that a rigger does this and it might not be legal for the jumper to do it. The reserve has to be re-sealed anyhow, so it's just as well to let the rigger do the whole procedure. To re-cock the unit you need to place a round screwdriver, or a designated "loop" through the eye at the end of the release cable. Stand on the
screwdriver, or the "loop" and pull the main unit straight up. Do not pull on the cablehousing or the airhose. Pull it steadily until it stops and hold it there for a few seconds. Do not pull too hard, or after the cable has been pulled to its outer position, as this can cause damage to the triangle spring, which controls the release mechanism. Release gently until it stops.
Calibrating the unit:
Always make sure the unit is set in the JUMP position before calibarting it. On earlier models it was necessary to take up any slack that was present inside the control unit when setting the altitude. This was done by first setting it to 4 (4000ft) and then go back down to 1 (1000ft). This should
not be necessary on models with the J-mod (FXC says it's not necessary), but there's no harm in doing it. Make sure that the needle is directly above the 1-line. There's a small
gap between the needle and the dial-face, so one could be fooled a little by the shadow effect that is created. After the unit has been calibrated for the day it is not necessary to do
anything with it unless the air pressure has changed
"significantly" (i.e. the needle has moved noticeable from the original position) or the unit has been turned off. The unit should always be in the JUMP position. This even includes when shipping the unit. It should only be set in the OFF position for short periods of time, which include going back down with the plane, landing in water, landing in deep snow, or before the trunk of a car is slammed shut with the unit inside it. The reason for this is that a membrane/seal that closes the valve for the air hose can be deformed because it remains closely pressed against the valve opening. This deformation can influence the firing altitude, as the membrane/seal does not close the valve sufficiently during regular use. In other words, turning the unit OFF and leaving it that way for a long period of time can increase the chances of the unit misfiring.
Finally, the unit should stay at least 15 minutes in the outside temperature before calibrating it, to make sure that all its components have reached the same temperature. Failing to do this could lead to a wrong setting, as changes in temperature could cause movements within the materials.
alan

[BadDog 0]

Alan, that's one of the most comprehensive explanations I've ever seen. Great job. Also, it's a great plug for Cypres.
CorporateLawyerDave aka BadDog

[RTB 0]

Alan, the FXC 12000 units that we have in Sweden do not need to be re-cocked after low pulls. This is after the latest modification ( J ). There might be a difference since we live in different countries but you should be able to get the same type of upgrade as we have.
My information comes from Paramecanic in Sweden who has been serving FXC units (and others) for as long as they have been around.
Otherwise great information as usual.
Sincerely
René

[riggerrob 643]

Would you like another explanation as to why you should let a Cypres shut itself off at the end of the day?
Consider that a Cypres only has two moving parts: the cutter and the switch. Moving parts wear a little bit every time they move. The less you move the switch the longer it will last.

[billvon 3,080]

>Do you know what the quiescent current is external to chip components--current
> level at the altitude sensor?--leakage current at fuseable link driver--(probably a
>pwr mos fet)
For everything other than the LCD oscillator, effectively zero - from what I could tell, the pressure sensor (a Wheatstone balance beam type, I think) is not biased when the unit is in standby. The only draw you see are the ON-leakages of the FETs for the firing and sensor-enable circuits and the LCD.
For FET leakage, a typical 20V, 10A peak FET gives you a forward leakage of around 100nA at 20C, so that's a minor effect. The problem with the LCD is that it has to have an AC voltage applied, but as there's been a lot of research into low-power LCD oscillators (all digital watches have an extremely low power one) I think that can also be a very minor drain.
-bill von