[ICOM] ICOM-R7000

[Steve]

Floyd,

As has been mentioned, these radios now have some serious age on them.
The most common failures are the electrolytic caps in the power 
supply stage and the DC to DC converter board. If the DC - DC 
converter stops supplying the odd voltages it is responsible for, it 
can knock out the RF, IF and PLL circuits.
There are also a pair or two of lytics that sit on the display board 
behind the EL panel that are responsible for driving the high voltage 
for the EL back lighting. It was mainly the lytics that ran warm such 
as those in the power supply stage that fail first and then the 
others shortly after.
When mine failed in the same fashion as yours, it was the caps on the 
dc - dc converter board. Search the internet as there were many 
changes made by Icom that are posted as service bulletins for that 
model. I think the actual service manual can also be found on the net 
although I seem to recall the schematics not being scanned very clear 
on the version floating around the net.
Somewhere, there was a site that had all the Icom service bulletins 
for the R7000 in a single PDF file. Some bulletins were simply mods 
for making improvements while others were about repairing some of the 
many common failures.
One of those bulletins was regarding the caps on the DC to DC board. 
I think those failed more from being ran near their voltage limit. 
After I rebuilt my dc to dc board, my R7000 ran like new but then 
started having display issues from a bad ribbon like cable that 
attaches from the display driver board to the actual EL panel. That 
one was a bear to fix.
I've since replaced pretty much all the electrolytic caps in the 
radio as I started seeing other issues. They dry out with age and 
usually give no visible signs they are bad unlike the caps used in 
more modern electronics that actually leak or bulge open. The modern 
cap failures were caused from a bad electrolyte formula but the 
lytics used back in the R7000 days simply dry out and change value. 
Then odd things start happening!
My R7000 has been running like new again for several years now since 
I replaced the caps.
Many also run them from an external 12 volt supply as that will keep 
a lot of heat out of the radio. Others have fabricated small fans 
running at low speeds that pull air through the radio. It does not 
take much air movement to keep the radio running at room temp but 
that can pull or push dust into the radio if you have a dusty 
environment. I've used both methods but have been running from 
external power for some time now as that supply also maintains a 
large SLA battery that keeps the radio running during power failures.

The R7000 is a very nice communications receiver and worth putting 
the time into fixing it up. There is no scanner made that can come 
close to the performance of the R7000. Put a scanner next to a couple 
hundred watt paging transmitter and it will either shut down its 
front end from desense or overload that it will become unusable 
across entire bands. Put the R7000 inline and it will not even know 
the paging transmitter is there. They are nearly immune to desense or 
overload issues unlike most scanner type receivers out there.
The R9000 is also of the age that they are seeing some dried out 
caps. I just recapped my R9000 recently but it was not showing signs 
of failure yet so I only recapped the power sections and then put a 
cooling fan on it.
Same goes for the fine HF receivers that Icom made during the same 
time period. Most have failing electrolytic caps.

You could also have a blown rf amp transistor somewhere in the rf 
stage from a nearby lightning strike but my bet is on the caps being 
at fault as mine also lost most sensitivity when enough caps failed.
Many stories also talk of the same problem and cure.

Good Luck!



At 10:05 PM 6/15/2013, you wrote:
>I have an icom R7000 Receiver that started out with bad sensitivity and now
>it does not hardly receive on any frequency except on local good time radio
>stations just fine. I can dial up my local volunteer fire department VHF
>frequency of 155.865 and receive nothing although a walkie talkie setting
>beside it receives OK. Now I can put a signal generator on 155.865 and put a
>piece of wire on the output and crank the signal up to 100K microvolts and
>receive that just fine.
>
>
>
>Does anyone have any suggestions on what may be wrong and how to fix it?
>
>
>
>Floyd
>
>----
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