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Author Topic: Problem with an Icom 718  (Read 6547 times)
K4IDK
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Posts: 38




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« on: November 19, 2011, 09:07:25 PM »

I was working the November Sweepstakes contest and all of a sudden my IC-718 quite receiving.  I did some playing around and it's all on the upper bands, 17m up to 10m that it's having problems.  On 20m and below it still works fine.  I can transmit, but can't receive.

Any ideas of: 1) what to look for that might cure it, or if that doesn't work, 2) where to send it to get it repaired?

Thanks,
Robert
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AD6KA
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Posts: 2237




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« Reply #1 on: November 21, 2011, 08:53:29 PM »

Have you tried a CPU reset?
Turn the power on while pushing UP and Down buttons.

I am not familiar with repair shops in your area.

GL ES 73, Ken  AD6KA
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K4IDK
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Posts: 38




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« Reply #2 on: November 22, 2011, 01:11:30 AM »

No, I never heard of a CPU reset.  I'll give it a try when I get back home. 

As for a repair shop, there's not one in this area that works on radios that I'm aware of, so I might wind up sending it off if it needs repair.
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N4NYY
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Posts: 4749




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« Reply #3 on: November 22, 2011, 07:57:07 AM »

If you cannot fix it, send it to Malcom Technical Support. First class icom repair.
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AC5UP
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Posts: 3844




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« Reply #4 on: November 22, 2011, 09:35:30 AM »

By the numbers.............

1) Go here: http://www.radiomanual.eu/ICOM.html

2) Scroll down until you see the Icom IC-718 service manual. Download same.

3) Adobe Acrobat may ask you if you want to install a JP font set. Your choice, but probably a good idea.

4) Scroll down to Section 12 and notice illustration 12-1 in the upper left corner. This is the filter board that carries the T/R relay plus six bandpass filters.
Each filter has a relay on the input and another relay on the output. That's how the filters are switched in and out of the TX line.

5) If one of those relays hangs or fails to switch the radio will not return to the normal RX passthru condition.
Translation: No RX on that band or (possibly) any band above it as the filters may cascade.

6) Go back a few pages in the service manual until you see Section 10, the block diagram. Note the bandpass filter in the upper right corner.
Notice how the last two bandpass filters are labeled 15 - 22 MHz and 22 - 30 MHz. If you flip the RX into general coverage and discover it pukes
at exactly 15 MHz, that's your clue-by-four the radio has a bad relay. Might want to tune above 22 MHz just to see if the RX comes back.

I think I've read that some of the newer radios have a relay cleaning utility buried in the menus. Check the user guide to see if this applies to the IC-718.
If not, consider farming the repair job out to a pro unless you are exceptionally talented with a soldering iron and are in good practice with same.............  Wink
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K4IDK
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Posts: 38




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« Reply #5 on: November 22, 2011, 11:26:11 AM »

WOW!!!  Where did you find all of that?!  It's a literal gold mine.

Oddly enough after I shut it off and powered it up the next day it worked fine, but I know enough about electronics, or anything for that matter, to know that if a problem shows up once and then disappears that it's not fixed and will return again eventually. 

Now I have a ton of information to download.  Call me an information hoarder, but when I find a source like that I download everything just in case someone might need it later.
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AC5UP
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« Reply #6 on: November 22, 2011, 11:57:15 AM »

WOW!!!  Where did you find all of that?!  It's a literal gold mine.

Don't blame me, AltaVista found the site for me years ago. Let's just say you can't fully appreciate how handy the Internet truly is until you get handy with a search engine......  Cheesy

Oddly enough after I shut it off and powered it up the next day it worked fine, but I know enough about electronics, or anything for that matter, to know that if a problem shows up once and then disappears that it's not fixed and will return again eventually.

It has been my experience that if a relay can stick, it can unstick, and I'm 98% certain that if you diagnosed the issue you'd be 99% certain there's a relay involved. Generally a relay will stick due to wear, total lack of lubrication, thermal expansion / contraction, or because something tried going crosswise and wedged. Many years ago I had a hard drive that wouldn't un-park the heads from a cold start. I "repaired" the drive by putting it in a freezer for 5 minutes.

Best guess is that a tiny little shift from thermal contraction was all it needed to un-bind the latching mechanism.
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G4FUT
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Posts: 88




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« Reply #7 on: January 30, 2013, 01:36:59 PM »

When I went here:-=
1) Go here: http://www.radiomanual.eu/ICOM.html
My virus checker said it was infected.
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Even if the voices aren't real, they have some pretty good ideas
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