R8500 went insensitive and noisy above 30Mhz

[Vegetarian]

The radio is just a year old and this suddenly happened just a day ago and now the noise jumps up to S5 on the signal meter with no antenna connected when I tune from 29.9999Mhz to 30Mhz. Sensitivity is low above 30Mhz now and I can only hear the strong broadcasts on the FM-band (87-108 Mhz) and some strong repeaters on 70cm.

The noise stay at about S5 up to 500Mhz where I hear a relay click and the noise drops a little. Then it gradually drops to 0 when I continue tuning up to 800Mhz. And this is with no antenna at all connected to any of the connectors.

The noise gets reduced with the the 10 and 20 dB attenuators so the fault should be before that in the circuitry I guess.

Also I hear no relay click at 30 Mhz, not sure if there was one before thou. If there should be, then maybe it's just the relay. Should there be a relay click at 30Mhz on the R8500?

Below 30Mhz it works fine, just as before.

Any ideas before I have to find someone to repair it.

 

[darkstar1461]

R8500

Sorry to read about your '8500. Mine suddenly went deaf in 2012 and I shipped it to an Icom repair facility. They sent me an e-mail stating flatly that the Icom Corporation "no longer supports the R8500 and repairs could not be done", and offered no solutions. They would not tell me what the defect was, and offered to ship it back to me, if I paid the shipping (again). I declined, and politely advised Icom I would no longer support their products. Good luck. Tom K2CIA.

 

[parnass]

Inspect your VHF antenna connector and feedline. Do you have a second VHF/UHF antenna you can try to connect to your IC-R8500?

As you know, there are separate antenna jacks on the back of the radio for HF and VHF/UHF and another jack for high impedance HF antennas. Did you change the configuration recently?

Was the antenna left connected during a recent thunderstorm?

 

[Vegetarian]

Parnass, thanks for reply. There has not been a thunderstorm here this summer yet.

And the antenna works. I can hear stronger stations when I plug it in. Also frequencies above 1 Ghz seem to work. Although I don't use it much so can't say if it's different from before.

And the internally generated strong noise that is there without any antenna was certainly not there before.

And darkstar, sorry to hear that. But the R8500 is still sold new so it would be strange if they don't do warranty repair. But to hear something like that from the dealer is certainly not fun. Can make anyone mad.

What I want to know guys is if you hear a relay click at 30Mhz.

 

[FrankNY]

There has not been a thunderstorm here this summer yet.

I was thinking that that might have been the cause of your problem as well, but if you say that there have been no thunderstorms lately, then that's not the case.

But the R8500 is still sold new so it would be strange if they don't do warranty repair.

Indeed, the IC-R8500 is still marketed, so it certainly ought be be serviceable by Icom.

What I want to know guys is if you hear a relay click at 30Mhz.

I'm not a vegetarian, Vegetarian , but just for you, I just fired up my IC-R8500-32K and tuned back and forth over the 30 MHz mark and can report that there's no relay click at that point. While performing this test for you, stepping was set at 10 kHz and I also tried various modes including AM, FM, USB, etc., all with the same result.

Many years ago I owned an IC-R7000 which did have a relay click somewhere in its tuning range, although I can't recall exactly where as it's been too many years for me to remember, but I can tell you that there's absolutely no relay click on my IC-R8500 at the 30 MHz mark.

Frank.

 

[parnass]

... I just fired up my IC-R8500-32K and tuned back and forth over the 30 MHz mark and can report that there's no relay click at that point. ....

FWIW, my IC-R8500 does not click when tuning past 30 MHz either.

 

[Vegetarian]

Many thanks to you both parnass and FrankNY for checking out the click, although a bit disappointing. Since my R8500 does not click either I can't conclude that it was just a faulty relay. But still a great help.

The good thing about this and probably other Icom radios is that all documentation with schematics and service description is available in case this things happens.

So thanks again guys.

 

[cg]

My 8500 sometimes clicks at 30MHz, if I go back and forth, it is very noticeable. The meter and audio (with squelch down) has a noticeable change at 30MHz when, I suspect, it changes antenna ports (I have no antenna on the HF port).

chris

 

[Vegetarian]

My 8500 sometimes clicks at 30MHz, if I go back and forth, it is very noticeable. The meter and audio (with squelch down) has a noticeable change at 30MHz when, I suspect, it changes antenna ports (I have no antenna on the HF port).

Chris, could it be that you have "REC REMO" on? that turns on a relay that activates with the squelch I think.

It's described in the manual under "Initial set mode items" if you want to turn it off.

 

[N4UMJ]

Converter Unit Bad Most Likely

I have encountered these several times in my years owning and repairing R8500's.

Specifically its a couple of tiny surface mount diodes and a transistor on the converter unit. A shield has to be desoldered as well as the connection to the N connector requiring some heavy heat from a soldering iron.

ICOM in Washington repaired this for me back in 2003. I have since repaired a few through the years that had the same problem. ICOM suggested in the repair details that it was most likely static or lightning damage. I was surprised as I use attic mounted antennas on that radio. I guess the emp from the next door strike took that R8500 out.

Sadly the 1st R8500 I bought used from a big dealer with "LIKE NEW" on tag and never verified the VHF/UHF sensitivity in detail. This particular failure will be obvious after an A/B receiver test. The radio shack was relocated at the time and had no good way to test the radio until a year had passed.

And yes you will see an elevated noise floor level on radios with that failure and was my first hint of this failure.

For what its worth my other repair encounters with failed R8500s have been varied. Some had PC board corrosion, bad internal speakers, failed encoders, bad resistor packs, PLL chip failures (low S/N's),

I have an attachment jpg showing the converter board removed and the lower left hand corner showing the area that had the failed components. They appear perfectly normal in appearance but will ohm out very low.

Ed
N4UMJ

 

[Vegetarian]

Thanks a lot N4UMJ, I will have a look soon.

If I should get my hands on a converter unit and just replace it, do I need to do some tuning adjustments afterwords to have the new unit in tune with the rest of the radio?

Bill

 

[Vegetarian]

Finally ordered a new CONV-B Converter unit. Replacement was easy if you have a 75w or more solder-iron. Actually instead of unsolder the old card from the N-connector I just bent it very slightly up and down many times until it came loose from the connector.

There was one adjustment on the new board but it is non-critical and was already correct.

The R8500 now works just fine and has all VHF-bands above 30mhz back.

Thanks again Ed for the tip.

Bill

 

[g6giy]

I have just got a R8500 with the same issue above 30 MHz . It needs about 10uV to fully quieten so I will have a go at Ed's repair. I suppose there has to be a downside to having such a sensitive receiver .

Phil G6GIY

 

[g6giy]

The repair went well,it was Q11 on the converter board that had gone duff .