[amsat-bb] Re: FT-847 Disaster

Jim Shorney jshorney at inebraska.com
Mon Dec 24 15:47:50 PST 2007

On Mon, 24 Dec 2007 15:04:55 -0800 (PST), Jim Jerzycke wrote:

>IIRC, the 847 has a "protection" diode across the DC
>input. Connecting the DC backwards will blow the fuse,
>and probably short the diode.
>You can download the service manual from the mods.dk

Most well-designed radios have this "suicide diode". It usually shorts, and
if it's not big enough and/or the fuse isn't fast enough, it will
subsequently burn open and the rest of the radio suffers damage.

The first thing the OP could do is find this diode and remove it from the
circuit. If the radio then powers up normally and works, luck was on his side
and all that needs to be done is replace the diode. If not, expect blown
power deviced in the radio and a trip to the repair shop.



Ham Radio NU0C
TR7/RV7, TR6/RV6, T4XC/R4C, L4B, NCL2000, SB104A, R390A, GT550A/RV550A, HyGain 3750, IBM PS/2 - all vintage, all the time!

HyGain 3750 User's Group - http://groups.yahoo.com/group/HyGain_3750/

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