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peter(at)sportingaero.com Guest
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Posted: Sun Apr 27, 2008 12:34 pm Post subject: Strange Exp-Bus Problem |
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Hi,
The last few times I have flown I have had a few strange 'brown-outs'.
It is most noticeable over the intercom as a short kind of shhuukkk
sound. Occasionally the radio (KX-135A) re-cycles and goes through its
re-boot routine. Initially I thought it was the master solenoid, but
thinking some more, I concluded that if the master solenoid were to
momentarily lose contact then the alternator would hold everything up.
The interrupts are usually of very short duration, such that I don't
notice most of the services blink, or by the time I have looked inside
everything is back on again. Sometimes it happens once every 5 or 10
minutes, sometimes not for a half hour or more.
I have an Exp-Bus DC load centre - I know that there has been some less
than complementary comments here about these devices (and I would not
fit one to an airplane I built, but I bought this one and I don't want
to rip it out). I'm now thinking that I am suffering some strange very
intermittent failure of this device (that I can't reproduce on the
ground).
Does anyone have any experience of the Exp-bus, or could suggest what
the fault might be?
Regards, Peter
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hooverra(at)verizon.net Guest
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Posted: Sun Apr 27, 2008 4:56 pm Post subject: Strange Exp-Bus Problem |
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Peter,
This is just a shot in the dark as I have no experience with the EXP
buss. I do have considerable experience with failed solder joints on PC
boards used in automotive applications. Look carefully at the solder joints
for a fracture either through the solder or at the junction of the solder
and heavy objects like relays. A magnifying glass helps.
PS if this doesn't help on the EXP Buss keep it in mind for Bosch relays as
used on Volvo, Saab and many others. 10 minutes may save you enough to fill
a gas tank twice:) I've fixed flakey auto instrument panels this way also
and that's way more than a couple tanks of gas!!
Ralph & Laura Hoover
RV7A N527LR
--
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mark(at)stratologic.net Guest
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Posted: Mon Apr 28, 2008 10:22 am Post subject: Strange Exp-Bus Problem |
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Hey Peter,
Check the electrical system closely for wire connector rings of the incorrect size. Eg. A too large ring over a connector stud.
If the connector rings are bigger than the stud, over time they vibrate and the resulting residue makes a poor contact. This will give you the exact fault you have…intermittent electrical faults.
I would check all the contactors connections, alternator connectors, etc..anything with a big ring connector. The culprit ring connector will look black when you take the nut off.
Don’t ask how I know so much about this problem J
Cheers,
Mark.
[quote][b]
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