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Nick -
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???
Bill Rumburg
----- Original Message -----
Sent: Tuesday, April 29, 2014 12:46
PM
Subject: [LML] Re: VMS1000 pressure
gauges on LNC2
Hi Bill,
(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.
Yours,
Nick
Sent: Tuesday, April 29, 2014 1:13 PM
Subject: [LML] Re: VMS1000 pressure gauges on
LNC2
Nick -
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.
Bill
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