MX 170B

I have a 1967 172 with a MX 170B nav/com. I noticed not long ago that
the display was flickering from bright to dim. Now the radio will not
come on at all. Any suggestions.

I have a 1967 172 with a MX 170B nav/com. I noticed not long ago that
the display was flickering from bright to dim. Now the radio will not
come on at all. Any suggestions.

Have you tried removing and re-seating it? I doubt it's that easy,
but you gotta try the easy stuff first.
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

Jack wrote:
I have a 1967 172 with a MX 170B nav/com. I noticed not long ago that
the display was flickering from bright to dim. Now the radio will not
come on at all. Any suggestions.

The "MX" is a replacement front end to the original KX 170b (made by a
defunct company called "MAC" if I remember right). It contains the
circuitry to convert the original non-lit frequency display "wheels"
into a more modern segmented lcd display. Most of these displays in
other radios contain a photocell to adjust the brightness according to
the changing conditions (from full sunlight to night). I am not sure if
this conversion readout has such a setup, but that may be the problem.
These cells and their related circuitry are usually pretty reliable though.

I have not taken an MX apart to see all that is involved, but it seems
reasonable that there some sort of connector from the MX front end to
the rest of the radio. This connection may be in need of
inspection/reseating. Call around to the avionics shops. One of them may
know a bit about these critters and may be able to save you some
troubleshooting time.

Anyone ever done this conversion?

Good Luck,
Mike

Jack wrote:
I have a 1967 172 with a MX 170B nav/com. I noticed not long ago that
the display was flickering from bright to dim. Now the radio will not
come on at all. Any suggestions.

First think to do is make sure your alternator is working (do you have
a voltmeter?). Flickering discharge displays are the first sign my
plane had that the voltage was getting low.

Jay Honeck wrote:
I have a 1967 172 with a MX 170B nav/com. I noticed not long ago that
the display was flickering from bright to dim. Now the radio will not
come on at all. Any suggestions.

Have you tried removing and re-seating it? I doubt it's that easy,
but you gotta try the easy stuff first.

The next step is to see if the display on the radio is seated (and the
connectors are clean). That's a frequent failure mode in the real
KX's with the discharge numbers.

Correction, I am not sure in the below posting if I am using the proper
names of the King KX 170B conversions/makers. I believe McCoy and Michel
made conversions of several kinds. MAC may be part of a conversion name
(representing McCoy?). Anyone know the history of these buggers?

Mike

I have a 1967 172 with a MX 170B nav/com. I noticed not long ago that
the display was flickering from bright to dim. Now the radio will not
come on at all. Any suggestions.

The "MX" is a replacement front end to the original KX 170b (made by a
defunct company called "MAC" if I remember right). It contains the
circuitry to convert the original non-lit frequency display "wheels"
into a more modern segmented lcd display. Most of these displays in
other radios contain a photocell to adjust the brightness according to
the changing conditions (from full sunlight to night). I am not sure if
this conversion readout has such a setup, but that may be the problem.
These cells and their related circuitry are usually pretty reliable though.

I have not taken an MX apart to see all that is involved, but it seems
reasonable that there some sort of connector from the MX front end to
the rest of the radio. This connection may be in need of
inspection/reseating. Call around to the avionics shops. One of them may
know a bit about these critters and may be able to save you some
troubleshooting time.

Anyone ever done this conversion?

Good Luck,
Mike

Jack wrote:

I have a 1967 172 with a MX 170B nav/com. I noticed not long ago that
the display was flickering from bright to dim. Now the radio will not
come on at all. Any suggestions.

It appears there may be an adjusting pot for the display brightness
control. A twist of this control slightly in either direction may bring
the display back or do nothing at all.

Good luck,
Mike

On Nov 3, 3:05 pm, Jack wrote:
I have a 1967 172 with a MX 170B nav/com. I noticed not long ago that
the display was flickering from bright to dim. Now the radio will not
come on at all. Any suggestions.

TKM will not release the service manuals so all work is done at the
factory. Lucky for you the 170 *B* is still supported. I have the
original "MX-170" and the factory refuses to work on it so its a door
stop.

-Robert

On Nov 4, 5:25 am, Mike Spera wrote:
Jack wrote:
I have a 1967 172 with a MX 170B nav/com. I noticed not long ago that
the display was flickering from bright to dim. Now the radio will not
come on at all. Any suggestions.

The "MX" is a replacement front end to the original KX 170b (made by a
defunct company called "MAC" if I remember right).

Different radio. That's the MAC-170B. The MX-170B is made by TKM.
Still very much in business and they just recently released their new
170C model.

-Robert

Mike Spera wrote:

Correction, I am not sure in the below posting if I am using the proper
names of the King KX 170B conversions/makers. I believe McCoy and Michel
made conversions of several kinds. MAC may be part of a conversion name
(representing McCoy?). Anyone know the history of these buggers?


TKM Michel makes slide-in replacments, which they call an MX-170. See
http://www.hawkinsassoc.com/Products...ucts/170b.html There were
also modification kits that changed out the mechanical selectors for a
digital front panel and reused the radio guts. I think those were made
by McCoy, and I think the conversion was a MAC something or other.
Michel is still around, I don't think McCoy is.

I have a Michel MX-11 in my plane. It has exhibited the symptoms you
described two or three times. Every time, taking the radio out,
cleaning the contacts and putting it back in has fixed it.