|
|
Bill,
Is this sensor actually working in your
VMS1000 or are you saying that it should theoretically work? If it is
actually working it seems to me that these less expensive sensors would be the
sensors of choice for replacement until such time as the entire VMS1000 system
craps out. Or I guess that is what you are saying??
Another Bill
From: Lancair Mailing List [mailto:lml@lancaironline.net] On Behalf Of William Rumburg
Sent: Friday, May 02, 2014 6:29 AM
To: lml@lancaironline.net
Subject: [LML] Re: VMS1000
pressure gauges on LNC2
My approach was to search for a transducer with the
same electrical parameters as the MediaMate, for which the VMS1000 fuel and oil
pressure indications were designed (i.e. 5VDC excitation and 50mV full-scale
output). Unfortunately, that turns out to be a combination rarely used in
industry; however, one version of the MSP US300 series has those
parameters, which makes it an exact electrical replacement. Furthermore, MSP
transducers are modern, high-quality and inexpensive - in contrast with
the antiquated, failure-prone and outrageously overpriced MediaMate. I
appreciate your efforts toward another solution, but why not go with the
US321???
----- Original Message -----
Sent: Tuesday, April 29,
2014 12:46 PM
Subject: [LML] Re: VMS1000
pressure gauges on LNC2
(Bill Rumburg, that is; there are two
Bills in the thread)
I don’t disagree with anything you
said. But the fact that the VMS-1000 DPU could be difficult to keep going in
the long term – liable to become toast as you say – makes me reluctant
to go for sensors that are specific to it. If my scheme works then I have
pressure sensors that might (not guaranteed, but might) work with another
display system. At least they will be industry standard and I’m also
going to use industry standard connectors, not the spade terminals.
If the fuel flow sensor failed, then I
would probably ignore it, at least for a while. But without OP and FP displays,
you have to take action immediately.
Sent: Tuesday, April 29,
2014 1:13 PM
Subject:
[LML] Re: VMS1000 pressure gauges on LNC2
The VMS-1000 was a state-of-the-art
engine indication/fuel management system back in the mid-90's and is still
quite respectable. However, it's DPU is comprised of individual electronic
devices which are now obsolete; hence, if any one of them is damaged or fails,
you may as well consider the entire DPU toast. The possiblity of damage to an
individual component is my reason for not experimenting with voltage dividers,
etc. in an attempt to make non-standard sensors work. Fortunately, sensors are
-for the most part- still available. One insurmountable problem, however, would
be replacement of the fuel flow sensor. FloScan went from an 18K to a 6K unit
and fuel flow accuracy requires that sensors "K" factor be programmed
into the DPU, which is no longer possible for the VMS.
The MediaMate's terminals are numbered 1
thru 4 and function as you've listed; however, terminals 2 and 4 are more
correctly identified as - and + 5 VDC excitaton, with terminals 1 and 3 as +
and - mV signal. I've also failed to mention that the MediaMate's plug-on
'Hirschmann' terminals are ill-conceived and problem-prone, especially for a mV
signal; whereas, the MSP US 300 series all have a permanent, factory-installed
connection.
|
|