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Author Topic: IC 706MK2 no power out  (Read 2453 times)
KB0SWO
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Posts: 13




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« on: January 12, 2011, 05:58:48 PM »

My IC 706mk2 has no power output on hf or 2M the diodes for power are ok... Started with no power... I disconnected r35 and the radio powers up but no rf out... problem started with my daughter plugging in the rj45 wire that was plugged into the radio into the rj45 jack on the computer instead of the digital interface... Is the fact I don't have this resistor connected the reason I have no rf output or is the problem deeper...I do have good recive but no output on any band... Is there a different value resistor I can replace this with as I don't have access to one of same value.  I know very little about test procedures and less about problem shooting any help is appreciated... Huh Huh Cry... I really don't want to use this radio as a scanner and can't afford to send it in because I can't afford it...
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AA4PB
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Posts: 12834




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« Reply #1 on: January 13, 2011, 07:00:51 AM »

Does the radio go to Tx mode when you key the PTT on the mike? If you put it in CW (key closed) or RTTY or AM do you get any power output? If you are testing in USB or LSB then you won't get any power output unless you get audio from the microphone. I expect given the RJ45 mishap that you have damaged the microphone preamp stage in the radio and thus are not getting any microphone audio.

Acutally, Icom uses a DC voltage on the mike jack that powers a preamp in the mike. You may have damaged the circuit that supplies the microphone bias voltage and thus no audio from the microphone.

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KB0SWO
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Posts: 13




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« Reply #2 on: January 13, 2011, 01:28:22 PM »

Nope there is no output in any mode... I did find out that the resistor I removed is some sort of voltage reference for the finals or something like that... The computer was not on when the cord was ugged into it or even turned on. The port on the computer still works.  I am starting to suspect that somehow I blew something on the pa board but I only have a multimeter with diode tester to work with so it is hard for me to do any testing. 
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KE3WD
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Posts: 5689




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« Reply #3 on: January 15, 2011, 06:49:29 AM »

... but I only have a multimeter with diode tester to work with so it is hard for me to do any testing. 

I have a couple shelves filled with various test equipments and the truth is that, faced with this scenario, the Multimeter would be my test instrument of choice here. 

*You know that something *after* that resistor is drawing too much Current.

Ohm's law plus the Resistance scales of your multimeter, along with the radio's schematic, you should start looking for the path of low resistance to Common in the circuits following that resistor.

Since the rig is blowing fuses and thus cannot be powered up, there are really no other pieces of test equipment that could be used here.  You gotta find the short and the multimeter along with the gray stuff between your ears is indeed the instrument of choice here. 

Hopefully the fault lies in some other component other than the finals.

73
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KB0SWO
Member

Posts: 13




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« Reply #4 on: January 15, 2011, 09:28:04 AM »

Yes I hope it's not the finals if it is the radio will be an expensive scanner/reciver. I am going to hopefully get back to working on this radio on monday evening as it is hard to accomplish alot with the daughter present, well other than finding new was to wreck stuff and having an endless list of parts doner electronics.
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KB0SWO
Member

Posts: 13




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« Reply #5 on: January 17, 2011, 11:29:38 PM »

Well unfortunatly the first fault i have found is the finals, from there i am worried that there are more problems in other boards... guess i will find out in a few weeks... Cry Cry Cry Cry Cry
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