Icom 251A All Mode Problem
 

Picked up a used IC-251A 2M all mode rig a few weeks ago. I left the radio
on today and when I went back to it the evening, the display was blank and
by listening, it appeared that it could not be tuned. Turned rig off and
back on. No joy. Unplugged from wall outlet. Full joy! obviously the rig
is partially powered up as long as it's plugged into the wall. Anybody see
this problem before? If so, what was your fix. Don't really feel like
tearing into full blown troubleshooting. Guess I would start at the power
supply, but most likely trouble is in digital logic area somewhere, or
around CPU. Bummer. Hate when that happens...

Scott
N0EDV


--
Scott
Gotta Fly or Gonna Die
http://corbenflyer.tripod.com
Building RV-4

" Picked up a used IC-251A 2M all mode rig a few weeks ago. I left the
radio
on today and when I went back to it the evening, the display was blank and
by listening, it appeared that it could not be tuned. Turned rig off and
back on. No joy. Unplugged from wall outlet. Full joy! obviously the
rig
is partially powered up as long as it's plugged into the wall. Anybody
see
this problem before? If so, what was your fix. Don't really feel like
tearing into full blown troubleshooting. Guess I would start at the power
supply, but most likely trouble is in digital logic area somewhere, or
around CPU. Bummer. Hate when that happens...

While this probably does not have anything to do with your problem. The
Icom rigs of that series have a logic circuit that is running on a battery .
If the battery goes dead the rig will quit and you have to send it back to
Icom for a new battery and new programming. There is (was ?) someone that
makes a memory circuit that does not depend on the battery.

" Picked up a used IC-251A 2M all mode rig a few weeks ago. I left the
radio
on today and when I went back to it the evening, the display was blank and
by listening, it appeared that it could not be tuned. Turned rig off and
back on. No joy. Unplugged from wall outlet. Full joy! obviously the
rig
is partially powered up as long as it's plugged into the wall. Anybody
see
this problem before? If so, what was your fix. Don't really feel like
tearing into full blown troubleshooting. Guess I would start at the power
supply, but most likely trouble is in digital logic area somewhere, or
around CPU. Bummer. Hate when that happens...

While this probably does not have anything to do with your problem. The
Icom rigs of that series have a logic circuit that is running on a battery .
If the battery goes dead the rig will quit and you have to send it back to
Icom for a new battery and new programming. There is (was ?) someone that
makes a memory circuit that does not depend on the battery.

On Sun, 7 Dec 2003 21:00:13 -0500, Ralph Mowery hath writ:

" Picked up a used IC-251A 2M all mode rig a few weeks ago. I left the
radio
on today and when I went back to it the evening, the display was blank and
by listening, it appeared that it could not be tuned. Turned rig off and
back on. No joy. Unplugged from wall outlet. Full joy! obviously the
rig
is partially powered up as long as it's plugged into the wall. Anybody
see
this problem before? If so, what was your fix. Don't really feel like
tearing into full blown troubleshooting. Guess I would start at the power
supply, but most likely trouble is in digital logic area somewhere, or
around CPU. Bummer. Hate when that happens...

While this probably does not have anything to do with your problem. The
Icom rigs of that series have a logic circuit that is running on a battery .

No, it does not. There is no battery in the IC-251/IC-551. (Hell,
these rigs were built before The Invention Of The Battery. HI!HI!)

On the back of the rig you'll find a slide switch just above the
fuse holder. Slide it to "OFF". As you guessed, there is an
small Always-On PS running -- when this switch is in the "ON" posn,
and it holds the memories across (front-of-the-rig) Power On/Power Off
cycles. My IC-551 exhibits the symptoms you describe. (My IC-251A
does not - yet.) As to why it doesn't work per factory spec's anymore --
my guess it's a combination of the small half-wave rectifier PS getting
ratty, plus the aging of the micro-processor (sic) chip, and the
number of direct hits by cosmic rays over the decades it's been in
service.

Since there are only 3 steenkin' memories in these rigs anyway, it's
No Big Loss to lose the memories. I simply leave both rigs on all the
time -- only unplugging them at times during ThunderStorm Season.
I use both rigs for weak signal SSB only. So, my memory "needs" are
trivial.

HTH
Jonesy
--
| Marvin L Jones | jonz | W3DHJ | OS/2
| Gunnison, Colorado | @ | Jonesy | linux __
| 7,703' -- 2,345m | config.com | DM68mn SK

On Sun, 7 Dec 2003 21:00:13 -0500, Ralph Mowery hath writ:

" Picked up a used IC-251A 2M all mode rig a few weeks ago. I left the
radio
on today and when I went back to it the evening, the display was blank and
by listening, it appeared that it could not be tuned. Turned rig off and
back on. No joy. Unplugged from wall outlet. Full joy! obviously the
rig
is partially powered up as long as it's plugged into the wall. Anybody
see
this problem before? If so, what was your fix. Don't really feel like
tearing into full blown troubleshooting. Guess I would start at the power
supply, but most likely trouble is in digital logic area somewhere, or
around CPU. Bummer. Hate when that happens...

While this probably does not have anything to do with your problem. The
Icom rigs of that series have a logic circuit that is running on a battery .

No, it does not. There is no battery in the IC-251/IC-551. (Hell,
these rigs were built before The Invention Of The Battery. HI!HI!)

On the back of the rig you'll find a slide switch just above the
fuse holder. Slide it to "OFF". As you guessed, there is an
small Always-On PS running -- when this switch is in the "ON" posn,
and it holds the memories across (front-of-the-rig) Power On/Power Off
cycles. My IC-551 exhibits the symptoms you describe. (My IC-251A
does not - yet.) As to why it doesn't work per factory spec's anymore --
my guess it's a combination of the small half-wave rectifier PS getting
ratty, plus the aging of the micro-processor (sic) chip, and the
number of direct hits by cosmic rays over the decades it's been in
service.

Since there are only 3 steenkin' memories in these rigs anyway, it's
No Big Loss to lose the memories. I simply leave both rigs on all the
time -- only unplugging them at times during ThunderStorm Season.
I use both rigs for weak signal SSB only. So, my memory "needs" are
trivial.

HTH
Jonesy
--
| Marvin L Jones | jonz | W3DHJ | OS/2
| Gunnison, Colorado | @ | Jonesy | linux __
| 7,703' -- 2,345m | config.com | DM68mn SK

Yes, I kinda figured it was something like that after discovering it would
go goofy if I left the Memory switch on and turned off the radio. Maybe
that's why the guy I bought from said he left it on all the time. Ah, the
nuances of old radios (at least there are no glass vacuum transistors in the
251!)

;)

I didn't think they had a button cell battery in them (or else they wouldn't
need no steenkin' switch on the back of the radio)...beins I'm getting lazy
in old age, I'll leave it alone and use the "work-around"...

Thanks for the insight.

Scott
N0EDV

"Allodoxaphobia" wrote in message
...
On Sun, 7 Dec 2003 21:00:13 -0500, Ralph Mowery hath writ:

" Picked up a used IC-251A 2M all mode rig a few weeks ago. I left the
radio
on today and when I went back to it the evening, the display was blank
and
by listening, it appeared that it could not be tuned. Turned rig off
and
back on. No joy. Unplugged from wall outlet. Full joy! obviously
the
rig
is partially powered up as long as it's plugged into the wall. Anybody
see
this problem before? If so, what was your fix. Don't really feel like
tearing into full blown troubleshooting. Guess I would start at the
power
supply, but most likely trouble is in digital logic area somewhere, or
around CPU. Bummer. Hate when that happens...

While this probably does not have anything to do with your problem. The
Icom rigs of that series have a logic circuit that is running on a
battery .

No, it does not. There is no battery in the IC-251/IC-551. (Hell,
these rigs were built before The Invention Of The Battery. HI!HI!)

On the back of the rig you'll find a slide switch just above the
fuse holder. Slide it to "OFF". As you guessed, there is an
small Always-On PS running -- when this switch is in the "ON" posn,
and it holds the memories across (front-of-the-rig) Power On/Power Off
cycles. My IC-551 exhibits the symptoms you describe. (My IC-251A
does not - yet.) As to why it doesn't work per factory spec's anymore --
my guess it's a combination of the small half-wave rectifier PS getting
ratty, plus the aging of the micro-processor (sic) chip, and the
number of direct hits by cosmic rays over the decades it's been in
service.

Since there are only 3 steenkin' memories in these rigs anyway, it's
No Big Loss to lose the memories. I simply leave both rigs on all the
time -- only unplugging them at times during ThunderStorm Season.
I use both rigs for weak signal SSB only. So, my memory "needs" are
trivial.

HTH
Jonesy
--
| Marvin L Jones | jonz | W3DHJ | OS/2
| Gunnison, Colorado | @ | Jonesy | linux __
| 7,703' -- 2,345m | config.com | DM68mn SK

Yes, I kinda figured it was something like that after discovering it would
go goofy if I left the Memory switch on and turned off the radio. Maybe
that's why the guy I bought from said he left it on all the time. Ah, the
nuances of old radios (at least there are no glass vacuum transistors in the
251!)

;)

I didn't think they had a button cell battery in them (or else they wouldn't
need no steenkin' switch on the back of the radio)...beins I'm getting lazy
in old age, I'll leave it alone and use the "work-around"...

Thanks for the insight.

Scott
N0EDV

"Allodoxaphobia" wrote in message
...
On Sun, 7 Dec 2003 21:00:13 -0500, Ralph Mowery hath writ:

" Picked up a used IC-251A 2M all mode rig a few weeks ago. I left the
radio
on today and when I went back to it the evening, the display was blank
and
by listening, it appeared that it could not be tuned. Turned rig off
and
back on. No joy. Unplugged from wall outlet. Full joy! obviously
the
rig
is partially powered up as long as it's plugged into the wall. Anybody
see
this problem before? If so, what was your fix. Don't really feel like
tearing into full blown troubleshooting. Guess I would start at the
power
supply, but most likely trouble is in digital logic area somewhere, or
around CPU. Bummer. Hate when that happens...

While this probably does not have anything to do with your problem. The
Icom rigs of that series have a logic circuit that is running on a
battery .

No, it does not. There is no battery in the IC-251/IC-551. (Hell,
these rigs were built before The Invention Of The Battery. HI!HI!)

On the back of the rig you'll find a slide switch just above the
fuse holder. Slide it to "OFF". As you guessed, there is an
small Always-On PS running -- when this switch is in the "ON" posn,
and it holds the memories across (front-of-the-rig) Power On/Power Off
cycles. My IC-551 exhibits the symptoms you describe. (My IC-251A
does not - yet.) As to why it doesn't work per factory spec's anymore --
my guess it's a combination of the small half-wave rectifier PS getting
ratty, plus the aging of the micro-processor (sic) chip, and the
number of direct hits by cosmic rays over the decades it's been in
service.

Since there are only 3 steenkin' memories in these rigs anyway, it's
No Big Loss to lose the memories. I simply leave both rigs on all the
time -- only unplugging them at times during ThunderStorm Season.
I use both rigs for weak signal SSB only. So, my memory "needs" are
trivial.

HTH
Jonesy
--
| Marvin L Jones | jonz | W3DHJ | OS/2
| Gunnison, Colorado | @ | Jonesy | linux __
| 7,703' -- 2,345m | config.com | DM68mn SK