[Motorola] Maxtrac 5 pin logic board question, HLN9123 basic limited masked board

Wed, 4 Jun 2003 16:01:28 -0400

Here's an answer I got direct instead of to the list.  I wanted to share
this as it seems not alot of people know or don't have the time to look and
find out.  Thanks a bunch Earl!

Oh, and I wanted to note that the tap point is not on the logic board, but
on the RF board, which on mine is a HLF9122A.  That board provides for
talkaround capability, but as long as the same chip is on the non-talkaround
board (HLF4095B) it should work as well.  Also he noted that you're better
off starting with a radio that has more than 2 channels, since many systems
rotate the data channel often and a 2ch rig might not cut it.  I'm lucky
here, the data channel never moves for either of the two systems I want to
track.

Oh, and while you're in the radio, i'd suggest pulling the speaker plug out,
you can't turn the volume down all the way on these things. Make a jumper
for the rear plug to grab audio if you want to check how the signal sounds
or make sure it's working. That way you can unplug it when you're done.

Shawn
KB8UDE

----- Original Message ----- 

> From: "Shawn Hastwell" <[email protected]>
> To: <[email protected]>
> Subject: [Motorola] Maxtrac 5 pin logic board question, HLN9123 basic
limited masked board
>
> Anyone know where I can pick up discriminator audio on these boards?  I
got a bunch of 800MHz chassis leftover after I pulled the 16 pin boards and
used them to upgrade other rigs to full signalling capable.  I threw the old
5 pin boards back in the 800 chassis and wiped them and re-init'd them as
800 conventional 2-ch units.  I want to put them to some use rather than
watch them go on ebay for 5 bucks each.  If I can get the baseband audio out
of them i'll use them as data channel radios for Treport, Trunker, and
E-Trunker usage.
>
> I don't have a service manual so any help would be appreciated.  Esp. if
someone has an extra manual they want to part with for a reasonable price.
>
> Shawn
> KB8UDE

I've grabbed the discriminator output from a 5-pin 16-channel 800MHZ
conventional maxtrac.  It was on a chip on the top side of the radio
behind the channel-up button.  The real hard part was finding a place
to install a phone jack in the side of the radio to neatly allow
connection from the outside.

I don't have a service manual, I just poked around until i found
somewhere that worked.

I remember writing up the procedure and either posting it somewhere ot
emailing it to a mailing list.  This was a few years ago.  I'll dig it
up and send it to you if you still need it.

Those maxtracs are great data source radios, but you really need at
least four channels and scan function to follow most trunked system
data channels when they swict freqs daily.

From: "Earl Barfield" <[email protected]>
To: <[email protected]>
Sent: Wednesday, June 04, 2003 9:43 AM
Subject: flat audio from a 800 MHz Maxtrac? (solved) (fwd)

> > Forwarded message:
> > >From earl Sun Aug 22 19:07:24 1999
> > Subject: flat audio from a 800 MHz Maxtrac? (solved)
> > To: [email protected], [email protected]
> > Date: Sun, 22 Aug 1999 19:07:24 -0400 (EDT)
> > Cc: [email protected], [email protected]
> >
> > > Anybody got a Maxtrac service manual and a minute to look something up
> > > for me?
> > >
> > > I've got a 800MHz conventional Maxtrac with the 5-pin connector on the
> > > back (specifically a D35MJA7DA6AK).  I'd like to use this radio as a
> > > dedicated monitor for the data channel on the local trunked radio
> > > system.  Where's a good spot to grab discriminator audio from this
> > > beast?  I know the 16-pin Maxtracs have discriminator audio available
> > > on the external connector, but this is a 5-pin connector.
> > >
> > > Thanks.
> > >
> > > -- 
> > > Earl Barfield
> >
> >
> > I'm kinda' disappointed that I only got one response on this question
> > and it didn't have the answer I needed.  Anyway, I figured it out and
> > here's the answer just in case anyone else ever needs to know:
> >
> > Discriminator audio is available on pin 6 of the IC on the top circuit
> > board that's right behind the "channel up" button.  This IC is marked
> > 79G05 and QLMD9035 on my radio.  There's a trace that goes off of pin
> > 6 to a solder pad.  I soldered on a 10uF tantalum cap and wired the
> > other side to an earphone jack that I mouned in the side of the radio.
> >
> > It works great and I've got a cheap, durable alternative to using a
> > scanner to drive the trunker program on my local trunked system.
> > These non-trunked Maxtracs can be had pretty cheap.  Even when you
> > figure in the cost to get it programmed, it's much cheaper than
> > something practically irreplacable like my Pro-2006.  I know the
> > Maxtrac will withstand being left on practically forever.
>
>
> -- 
> Earl Barfield  --  Operations Department / Information Technology
> Georgia Institute of Technology, Atlanta Georgia, 30332
> Internet: [email protected]    [email protected]
>           [email protected]         [email protected]
>