Icom IC-706mkiig intermittent receive

[W5BRM]

I posted this over on the Zed. Thought I'd cross post it here to see if anyone could help diagnose it as I know a lot of you dont do the zoo. Thanks for reading

Hi. I have an Icom IC-706mkiig that has been sitting on the shelf for several years. About 8 or 9 months ago, I brought it down and hooked it up to an antenna and powered it up. It received OK for several minutes then the receive quit. I didn't try the transmit as the antenna wasn't tuned at that point. Once the receive quit, I tried looking at my coax and antenna to see if that may be the issue.

The coax works ok. Tested it with continuity tester. No shorts or anything out of the ordinary. Tried the coax on another piece of gear and it worked fine.

The antenna was a random length long wire. nothing special.

The power supply is ok. had a friend with better gear then I check it but I don't remember what his readings were. Only that he said it was working OK

While the rig was receiving, I was getting good signals, atmospheric noise etc. Then it just quit. The radio powered on but nothing. just a light hiss thats the usual for a receiver not hooked to an antenna. The screen came on and I got the everything thats supposed to be there. I repowered the radio several times and couldn't get the receive to come back on.

I put the radio back on the shelf for a few months then I brought it back down to take another look at it. Did the same thing. Hooked it up to power supply and antenna and the radio powered on OK, The receiver worked ok then after several minutes it just quit again. Once again, I put it on the shelf and after 3 months, tried it again and got the same thing.

Anyone have any idea on what might be the problem? The fact that it receives then quits and receives again after a long period of power down i think is a clue but I cant figure it out. Google is no help.

I'm planning on sending it to a repair guy but I thought I would drop a message here to see if anyone has had the same thing happen with their rig. I'd kind of like to be able to give the repair guy a few ideas so he has a place to start. Is there anything simple I could try before i spend some serious $$$ on getting it fixed?

Thanks

Brian/N2NKW

[NQ6U]

Found this, might be helpful:

https://groups.yahoo.com/neo/groups/...s/topics/18121

[W5BRM]

hmmm interesting. When I get home, I will look into that. I don't have a heating issue and that seems to be what his problem is but it might put me on the right path. I'm also looking into leaky or swollen capacitors per an answer on the zed.

Thanks!

[K7SGJ]

The first thing I would do, is perform a hard reset acording to the manual. Once that's done try it out. If it's still shows the same thing I'd want to exercise the T/R relay by pushing the PTT switch several times. Radio to a dummy load or antenna of course. I'd certainly want to check the menus and control settings, too. I can't remember if there is one control that can be set for function as RF gain or squelch.

Just a good starting point to eliminate all the coomon oops stuf and cockpit error.

[W5BRM]

The first thing I would do, is perform a hard reset acording to the manual. Once that's done try it out. If it's still shows the same thing I'd want to exercise the T/R relay by pushing the PTT switch several times. Radio to a dummy load or antenna of course. I'd certainly want to check the menus and control settings, too. I can't remember if there is one control that can be set for function as RF gain or squelch.

Just a good starting point to eliminate all the coomon oops stuf and cockpit error.

That was the 1st thing I did. Hard reset does nothing. I did try the mic briefly for a second or 2 but there was no response from the radio. no relays click, no hum nothing. that was while the radio was not receiving. I haven't tried it while the receive works yet but when I get home, I'll give it a shot. I dont see this as a menu issue. The receive suddenly stops without me touching anything so its a hardware issue not a software or menu issue. Maybe heat related but that even seems unlikely as the radio only operates on receive for 1-3 minutes without transmitting so doesn't have time to heat up to make a component fail.

[WX7P]

Maybe it's just the squelch being set too high

on edit: looks like Mr. Desert Rat already covered that one.

[N8YX]

Depending on what sort of test gear you have at your disposal, you might try injecting signal at the AF amp stage and check it. Then work your way backwards through the detector stages and into the IF.

Does the radio lose reception on all bands, just the HF portions, just the VHF/UHF segments, ?

[W5BRM]

Does the radio lose reception on all bands, just the HF portions, just the VHF/UHF segments, ?

everything. like someone flipped a switch. It was mentioned on the zoo that it might be leaky or swollen or failed capacitors so thats the 1st thing im looking at as its mostly visual inspection.

http://forums.qrz.com/showthread.php...uits-receiving

I only have my eyes and an assortment of screwdrivers. Don't have any real test equipment. I did the coax check by using a lighted ground tester probe and a battery.
Thats the extent of my test equipment at this point. Over the next few months, i plan on getting multimeter and other stuff but as I'm pretty much equipmentless at the moment, all i can do is visual stuff. If I can find an obvious thing like keaky caps or damage to the board or components, then I will at least be able to give the repair guy a head start on fixing it.

[kb2vxa]

Actually you DO have a heat issue, with so much stuffed into a small case the fan comes on soon after power on and runs continually at low speed. I'd suggest freeze spray to isolate the defect, but you can't get at much without taking the whole thing apart. Good old fashioned DIY repair is impossible without expensive equipment not found in the average shack so it's time for attention by a professional. Being out of production for so long I doubt Icom would repair it.

Now if I can find a latch to keep the faceplate on mine in place I'd be a happy ham. It was packed in the original box with the original packing material during my last move, it fell and landed JUST right... snap.

[N2CHX]

That was the 1st thing I did. Hard reset does nothing. I did try the mic briefly for a second or 2 but there was no response from the radio. no relays click, no hum nothing. that was while the radio was not receiving. I haven't tried it while the receive works yet but when I get home, I'll give it a shot. I dont see this as a menu issue. The receive suddenly stops without me touching anything so its a hardware issue not a software or menu issue. Maybe heat related but that even seems unlikely as the radio only operates on receive for 1-3 minutes without transmitting so doesn't have time to heat up to make a component fail.

Not necessarily true. If a component is heating up internally, it could fail in a matter of seconds even if it was sitting in a freezer.

When receive audio dies, what's on the signal meter? Anything, or does the signal go away as well as the audio?
If you hook a signal generator up to it, is it totally and completely deaf, or can it still receive a very strong signal?

My guesses:

* failing component, which could be identified fairly easily by probing with small amounts of freeze spray.
* cold solder joint, which could be identified by banging around on the boards a bit with the blunt end of a plastic screwdriver.
* a loose ribbon connector, which could be found by doing a little wiggling.
* corrosion on a connector, between component pins or on a board somewhere. This one seems likely seeing as how long it was in storage.

Even a cold solder joint or loose connector might not react to physical shock like wacking on the case. Someone's going to have to dig into the internals of this rig and start banging on boards, pulling on ribbon cables and hitting it with freeze spray.