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IC-756PRO No Audio at start up.

I bought a used 756 Pro in mint shape, recently it has developed a problem that i have already seen in 2 other friends ICOMS 756 which they sent out under warranty to have repaired. from what i understand its a bad solder joint some where in the audio circuit (most like the Amp) that is cracked and heels it self when the rig warms up . Well now i own one of those, i am going to repair this my self and thought maybe some one else may have already located the faulty area so that it will save me some time finding it.

thanks.

Reply to
Jamie
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Congrats on getting ready to repair this yourself Jamie - THAT......is the stuff that REAL HAM RADIO is made of! Although you might indeed find someone who'll give you a "silver bullet" (actual quick fix), I'd highly recommend just digging out the schematic AND circuit board layout drawings and troubleshooting this logically. Although I don't have those drawings myself, if you do and would like to share them (just the sections applicable) I'd be glad to help/guide you with the troubleshooting and repair.

73 - Gord VE1AJF
Reply to
GS

Den Thu, 10 Mar 2005 12:26:45 -0800. skrev Jamie:

You can find the servicemanual here:

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Gentle tap with the plastic end of a small screwdriver at the components in af section might help you.

Audio amp ic's are good at unsolder themselves, especially in mobile units.

Happy hunting

Vy 73's de oz1gnn

Christian Treldal

--
Med venlig hilsen 

Christian Treldal
Reply to
Christian Treldal

yeah ok, i have been doing some research and apparrently its the relay that deactives the specker while the unit is initiating. i haven't taken the rig apart yet because its not totally dead! since i have the accessory being used for Slow scan i still can hear it fine in the computer speakers! :) but in any case, i have determine that hte relay coil must be getting partial current and maybe even noisy current (bad joint), but do not notice it due to the fact that relays have a Peek and Hold current! once the relay gets enough to latch down, the holding current can reduce and not effect the unit. so this looks like a solder joint in the circuit that is operating the relay, most likely a transistor that runs hot or the relay runs hot and does not have enought heating venting between the relay body board which is causing the board to heat contract to much and thus forming bond problems in the joints of the coil legs. etc.. i will get to it one of those days :)

Reply to
Jamie

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