Fuel "Control monitor" or "Signal conditioner"

[Pete Somers]

Roger
You have the resistor type system on your T337D, now this system requires quite a bit of maintenance, the grounding of the tank unit has to be 'spot on' if you have any corrosion under the tank units or the ground strap is not clean this system will not work correctly.
On the resistor type system a open circuit from the gauge to the the tank unit will cause full scale deflection of of the fuel gauge, and a short would cause the opposite effect.

Easy check for volts at the tank unit, also check that the tank unit is grounded and no corrosion on any of the connections.

Regards
Pete

[edasmus]

Update: I spoke with Aero-Mach a few hours ago and they are sending my signal conditioner back and they feel they have it working per spec under all conditions now. They found several things wrong and feel they have the unit repaired. I should have it by Monday so I will keep you all posted as to the results. They did say however if I still have problems, they would not attempt another repair but would only sell me an overhauled unit. Aero-Mach did not charge me any additional amount for the second round of repairs so kudos to them. I hope it works when we get it all back together. Stay tuned!

[edasmus]

The signal conditioner arrived today and I promptly went out to the hanger to hook it up. It PROMPTLY failed. My IA got the same intermittent behavior on the gauges by wiggling the 9 pin plug that is attached to the signal conditioner. Aero-Mach is sending an overhauled unit tomorrow to see if I get the same behavior with that one. This is fun.

[Ernie Martin]

I was kind of unhappy when I gave up on the system and now rely on fueling supervision, visual confirmation and time. After hearing what you're going through -- no longer unhappy.

Ernie

[edasmus]

hahahahaha.....Thanks Ernie, that was funny!

[edasmus]

I received the over-hauled signal conditioner on Friday and plugged it in today (Monday). It has the same erratic behavior as my original one.

[edasmus]

Does anybody know what it means, as far as the fuel gauges are concerned, when turning the master switch on causes the gauges to indicate negative or in other words, below empty. When the gauges work, they work fine. When they don't, they indicate below empty. If you turn the master switch off when the gauges are indicating negative, they rise slightly and indicate empty. When the master switch is turned on and the gauges are not working, they get "sucked" below empty. It is probably a short somewhere. Anybody have any theories?