[Icom] re sick IC-745

Wed, 05 Feb 2003 21:12:27 -0500

Fern,

If you don't have a frequency display, the Logic Unit or RAM Unit is most 
likely where the problem is. Since you subbed in a known good EX-314 
already, look elsewhere. Even with the VCO caps bad and an unlocked PLL, you 
will still see a frequency display. Check for bad solder joints or cracked 
traces around the Logic Unit PCB header pins where the EX-314 RAM Unit plugs 
into the Logic Unit, and check the Vcc source on the Logic Unit board, also 
make sure the outputs from the Regulator Unit (on the radio left sidewall) 
are OK.

All that being good, probe around the processor and look for heartbeats, it 
sounds like the uP is not running and executing opcode from RAM to 
initialize the radio. If you see a good uP clock, there should be activity 
on the processor when the main dial is changed, or when any other main 
function is exercised.

It could be simple, or it could get real ugly . . .

Good Luck.

73, Frank W3UHF

>From: "Fern Rivard" <[email protected]>
>Reply-To: [email protected]
>To: <[email protected]>
>Subject: [Icom] re sick IC-745
>Date: Wed, 5 Feb 2003 18:24:39 -0800
>
>     I just acquired another Icom IC-745 transceiver. I found that the
>lithium battery in the ram board was dead. I substituted the good ram board
>from my good working 745 but radio was still dead (no receive or transmit
>and no frequency display). I then hooked my spectrum analyser to the output
>of the VCO and no output there. It does not receive or transmit on any of
>the bands so I would think that it's not likely that it's just the VCO caps
>that need replacing or do they all go bad at once??  Anyone with a lot of
>experience on these that could give me some more insight as to what to 
>check
>out next.  I will be ordering the Nardo memory board from IK2RND rather 
>than
>use the unreliable original Icom ram board.
>     73 from Fern
>
>
>----
>Your Moderator: Dick Flanagan W6OLD, [email protected]
>Icom Users Net: Sundays, 1700Z, 14.315 MHz
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