ICOM-751 dead, help
 

ICOM-751 dead, help

I was using my radio just fine, than I unplugged it and moved it a few feet
and now it is almost dead. I can hear a relay engage when I first turn it on
and fall off about 10 seconds after I turn it off.
What happened?

Burt wrote:

I was using my radio just fine, than I unplugged it and moved it a few feet
and now it is almost dead. I can hear a relay engage when I first turn it on
and fall off about 10 seconds after I turn it off.
What happened?

-The batteries backing up the SRAM holding your transceiver's operating
system went dead; you will need to send it back to ICOM for reprogramming.

Or, if you're lucky, one of the replacement boards offered by third parties
come with preprogrammed software.

The reason? For some strange reason, ICOM decided to keep the OS in SRAM,
which loses its contents if power is removed. Probably, SRAM chips were
a few cents cheaper than a similar-sized EPROM. Tough luck.

Do a google search on "ICOM 751 SRAM battery backup board" or something
to that effect, and you should find a solution.

Myself, I modified the original board so that two battery cells were
connected in parallell, separated by a schottky diode. That way, I can simply
change one battery at a time without losing the data which keeps my rig
ticking.

--
73 de LB1LF

Odd Erling, ARK

Why did kamikaze pilots wear helmets?

"Lloyd" wrote

|
| Why would you use an expensive Shottky diode in a lowly battery
| circuit?

Shottky (hot-carrier) diodes are not particularly expensive and they are
ideal in this application because of their low forward resistance.

Most modern HF rigs above the "entry level" price point use dozens of
Shottky diodes for front end switching and T/R switching applications,
due to their speed and high PIV.

73, de Hans, K0HB
--
Lord High Liberator of the Electric Smoke