Unusual ICOM R7000 problem

[danesgs]

Everything on the radio works (for awhile, like 2 minutes) cold. Then you loose a signal until you power off and power it back on. The PLL cuircuit is fine I guess, I can tune around such as NOAA and let it sit there then in 2 minutes the signal is just static. What is throwing me is if its caps going bad turning it off/on should not bring the signal back but it does. Again for a short period of time. Any ideas? IF its a "witches hat" solder connection, running hot would cause a connection to go bad, but simply turning it off in that that should not cause the signal to return.

Anyone seen this before and can tell me where to look?

 

[Hit_Factor]

Matt at sarts1 can help if you don't figure it out yourself.

 

[majoco]

Does the signal fade out as in signal strength or does it drift off in frequency?

The PLL cuircuit is fine I guess, I can tune around such as NOAA and let it sit there then in 2 minutes the signal is just static.

So it's not fine.

There is a DC-DC voltage converter that supplies all sorts of voltage to many other circuits that has some electrolytic capacitors on the board that are known to fail and produce all sorts of problems. Not an easy thing to get to and don't get confused with the display DC converter.

Icom R7000 PLL Fault - Help Needed

Hi, As a bit of background about an Icom R7000 with a PLL fault that I am trying to fix. I recently bought a R7000 to do up to sell. It was being sold as faulty and based on the description of the fault, it sounded a lot like the typical caps on the DC/DC converter and on the display. When I...

forums.radioreference.com

 

[danesgs]

No fading, its just there and then it goes to static sort of like it went of the air. I will look at the caps in the DC to DC board, thanks for the schematic as well.

 

[danesgs]

Matt at sarts1 can help if you don't figure it out yourself.

Thanks for the link to Matt, funny St. Joe was where Heathkit got their start, I worked for Heath for 10 years. St. Joseph must breed repair guys

 

[Hit_Factor]

He lives a couple blocks from me. He worked at Heathkit, along with a bunch of people in our ARC.

 

[danesgs]

Small world. Best 10 years of my life actually, (1982-1992). Computers were just becoming personal, Robotics were new to the hobbyist Most all the feds were running analog lol. Cell phones looked like military PRC-6 walkies. The only regret was the music was "disco". The Jurassic period of the digital age....

 

[majoco]

I'm still holding my breath waiting to see if you've fixed it or sent it away.....

 

[danesgs]

It is now working running only off of external 13.8 volts DC adapter. ICOM put in a DC molex socket, shorted it out to disable it and covered the place it would have gone with a brass plate. I read a single reply here that I must have missed about this. IT is now running off a Laptop AC adapter and has been working nonstop for 3 days. I did do the DC to DC board and Reg board cap replacement but and pretty sure the heat issue is the transformer in the AC side. Did not want to spend a lot of money for shipping especially at 17 pounds to and from an ICOM repair place.

So for folks with the R7000 that "runs hot" has other issues, look for that molex socket next to the Reg board with a shorting jumper, that's your DC power in. It will have a red, yellow and black wire but the only two being used are the red and black.

 

[majoco]

So do you think it was changing the caps in the DC-DC converter board that fixed your problem? The heat in the power supply is a well known defect and most sufferers now use an external power supply - mine came with the rear panel connector already installed but no power lead so I made one out of a computer hard drive plug. I have drilled a lot of holes in the rear top and bottom of the cabinet which also helps to keep it cool - but it does sit on top of my homebrewed power supply which supplies everything that runs on 12v so in itself generates a bit of heat. IMHO most of the R 7000 radio heat comes from the voltage regulator and the rectifier bridge on the back of the cabinet - I investigated mounting a larger heatsink but in the end the external power supply works well enough.

 

[danesgs]

I think the cap replacement helped. But mainly the fact the AC transformer is no longer putting out heat is a big reason its working continuously. I had no display problems indicative of capacitor issues in the DC-DC board and elsewhere. Running off the 13.8 volts is a lot cheaper than shipping a 17 lb radio plus the repair cost plus the shipping cost back. I think the AC adapter at 13 volts 3 Ah ran me like 21.00. Its a kludge but it works.