I have a Navico AMR-1000 2 Metre transceiver with a strange fault. I cannot
use the set to transmit, change freq. or illuminate the LCD display. In
other words, none of the panel controls work. Whenever the mic is removed
from the 8-pin socket, all is OK! However, when the mic is removed and the
display is set to 'channel' rather than frequency, the set starts scanning
through the band as soon as the mic is replaced.

It is NOT the mic or cable!

I checked out all mic and PTT, and the up/dn selector switches. With the
mic completely removed from the set and a 10K resistor is connected to the
mic pins at the set socket, it all goes faulty again. It is when a mic
impedance or equivalent is connected to the set that things go awry; all
switch-buttons are working normally.

The only thing to link the mic and the other functions is the control
processor, as a sniff of the mic is connected to the processor (HD4074608)
via a pad consisting of a 10K and 47 K resistor (toneburst output, generated
in the processor and fed to the mic - acting as a speaker - so it can be
heard when the PTT is operated). The fault is intermittent(ish) as all is
OK for a short time whenever I open the set up and remove the 16-way plug
linking the front panel to the main set, and replace it afterwards. I have
checked all connections and not found any dry joints.

I am rather hoping it is not the processor which is faulty! Have any Navico
users experienced a problem like this - and discovered what was doing it?
All info appreciated.

--

Regds,

Russell W. B.
http://www.huttonrow.co.uk

Please replace appropriate text with punctuation to reply!

"Russell W. Barnes" russell dot barnes @ huttonrow dot co dot uk wrote in
message news
The only thing to link the mic and the other functions is the control
processor, as a sniff of the mic is connected to the processor (HD4074608)
via a pad consisting of a 10K and 47 K resistor (toneburst output,
generated in the processor and fed to the mic - acting as a speaker - so
it can be heard when the PTT is operated). The fault is intermittent(ish)
as all is OK for a short time whenever I open the set up and remove the
16-way plug linking the front panel to the main set, and replace it
afterwards. I have checked all connections and not found any dry joints.

I am rather hoping it is not the processor which is faulty! Have any
Navico users experienced a problem like this - and discovered what was
doing it? All info appreciated.


I'd suspect a break in the ground circuit between the front panel and main
ciruitry or in the uP area. As you've checked joints etc, maybe a cracked
PCB track?

Navico still exist but under a the name Simrad and are still in the
Broadstairs area. I'd be surprised if they have anyone who remembers this
set you can talk to but they may be able to supply a circuit.

73

Brian

"Brian Reay" wrote in message
...

"Russell W. Barnes" russell dot barnes @ huttonrow dot co dot uk wrote
in message news
The only thing to link the mic and the other functions is the control
processor, as a sniff of the mic is connected to the processor
(HD4074608) via a pad consisting of a 10K and 47 K resistor (toneburst
output, generated in the processor and fed to the mic - acting as a
speaker - so it can be heard when the PTT is operated). The fault is
intermittent(ish) as all is OK for a short time whenever I open the set
up and remove the 16-way plug linking the front panel to the main set,
and replace it afterwards. I have checked all connections and not found
any dry joints.

I am rather hoping it is not the processor which is faulty! Have any
Navico users experienced a problem like this - and discovered what was
doing it? All info appreciated.


I'd suspect a break in the ground circuit between the front panel and main
ciruitry or in the uP area. As you've checked joints etc, maybe a cracked
PCB track?

Navico still exist but under a the name Simrad and are still in the
Broadstairs area. I'd be surprised if they have anyone who remembers this
set you can talk to but they may be able to supply a circuit.

73

Brian


Hi Brian, and thanks for the info.

I have a cct and some information, but not a complete svce manual. I shall
certainly keep looking for broken tracks, etc! I have seen SIMRAD's
website, and Emailed them about a mounting bracket for this particular set -
no rely yet... (

The head is joined to the set by a ribbon-cable which is designed to be
twisted to allow up-side-down fitting of the head. It might be intermittent
as well, as might be the IDC plug to which the ribbon is connected.

Tnx once agn,
--

73's,

Russell W. B.
http://www.huttonrow.co.uk

Please replace appropriate text with punctuation to reply!