[ICOM] R70 issue

Sat Nov 5 21:52:46 EDT 2016

Hello all,
  A follow up on this problem as many have offered help. I had to  
back away for a bit to re-think plus take care of other business.
My R-70 is now operating normally as it should but I can't tell you  
exactly why. i hate it when that happens. After my 're-think' I re- 
seated all connectors and cleaned all controls (again).  I started  
thinking of a mechanical as opposed to electrical problem and my gut  
feeling is 'yes'. Unfortunately I wasn't very scientific in my  
approach to check each stage one at a time.
I finally realized that the radio has been in general coverage mode  
for quite a looong time so I recycled that button with cleaner  
several times. Also, there is a switch on the back to change between  
the co-ax antenna connector and a simple long wire that I've never  
used. Cleaned and worked that several times.
Bingo!
It sure is nice to have a source of knowledge like this reflector to  
bounce things off and figure things out.
73,
Steve k7dna

On Oct 14, 2016, at 6:10 PM, Steve Sutfin wrote:

> Thanks all for the useful (and fast) replies.
> Christian,
>  I'm aware of the Icom trimmer cap problems since most of my  
> research info came up on the R71 & IC751 units. What I found that  
> seemed consistent with the trimmer caps was no output on certain  
> bands but not all. When mine goes it's across the board. That said,  
> it is definitely on my radar.
> Mort,
>  I get steady 13.8v & 8v on all the connectors I can find so I was  
> ruling out the PS caps. Now I'm going to keep the various stages  
> hooked up for a while and check the voltages when the problem occurs.
> tnx agn everyone,
> Steve k7dna
>
> On Oct 14, 2016, at 9:58 AM, Ron via Icom wrote:
>
>>
>>
>> Hi. Better caps are those rated at 105 C....
>>
>> ron
>> N4UE
>>
>>
>> -----Original Message-----
>> From: f1gwr <f1gwr at free.fr>
>> To: ICOM Reflector <icom at mailman.qth.net>
>> Sent: Fri, Oct 14, 2016 2:43 am
>> Subject: Re: [ICOM] R70 issue
>>
>> Hi,
>>
>> Mort may be right.
>>
>> But one common issue is the VCO capacitors. Not only the  
>> electrolytics but also the trim caps. Thanks Icom they didn't give  
>> out the value of these caps, only unknown references, uh! If I  
>> remember well they should all be replaced by 10 or 12 pF. After  
>> realigning the VCO after the Service Manual, this solves the  
>> problem. There are a lot of references about this problem on the  
>> net, but found one that states one of the lower value trim cap  
>> (around 6 pF) must be replaced by a larger value than initially  
>> for best results.  I read that if you replace all caps by 10-12  
>> pF, you still have lowest cap value to obtain PLL capture over the  
>> full range.
>> HTH.
>>
>> Best 73
>> Christian F1GWR
>>
>> Le 14 oct. 2016 à 07:09, "Mort Arditti" <marditti at dslextreme.com>  
>> a écrit :
>>
>>> Steve,
>>>
>>> The R70 is a senior citizen.
>>>
>>> One possible issue may be electrolytic capacitors causing DC voltage
>>> problems.  These devices 'dry up' with time which causes
>>> capacity loss and high leakage.  If you have the means to check  
>>> the various
>>> DC voltages and ripple.  This will require an
>>> oscilloscope.  The power supply has large such capacitors.   
>>> Sometime as
>>> capacitors age, you may see some bulging and/or
>>> some build up on the positive end wire lead near the seal.  This  
>>> is a sign
>>> of bad capacitor.
>>> If the voltages are proper and minimal ripple (guess at <50 mV  
>>> peak to
>>> peak), it is not the capacitors.  On the other hand if the
>>> much higher start replacing electrolytic capacitors.
>>>
>>> If indeed it is capacitor issue, replace them all.  Observe  
>>> proper polarity
>>> - this is very critical.
>>>
>>> For long reliable life make that the capacitor are rated for 85  
>>> Deg. C and
>>> low ESR.
>>>
>>> I hope this helps.
>>>
>>> 73,
>>>
>>> Mort,  NA6MA
>>>
>>>
>>> -----Original Message-----
>>> From: Icom [mailto:icom-bounces at mailman.qth.net] On Behalf Of  
>>> Steve Sutfin
>>> Sent: Thursday, October 13, 2016 9:38 PM
>>> To: ICOM Reflector
>>> Subject: [ICOM] R70 issue
>>>
>>> Hello to the list,
>>>  My Icom (aged) R70 receiver started having a problem after xxx  
>>> years of
>>> good service. When I turn it on sometimes there is no signal,  
>>> just the usual
>>> background noise. But after a bit it comes to life like normal  
>>> but the
>>> signal dies after 30 sec. to 3 minutes. The voice doesn't get  
>>> distorted when
>>> it quits but sounds more like wind blowing across the mic. If  
>>> left on it
>>> comes back and sounds like normal for a bit then goes out. All  
>>> voltages I've
>>> traced on the schematic are fine but my test gear is basic.
>>> Any thoughts?
>>> tnx & 73,
>>> Steve k7dna
>>> ----
>>> Your Moderator: Dick Flanagan K7VC: icom-owner at mailman.qth.net  
>>> Icom Users
>>> Net: Sundays, 1700Z, 14.316 MHz Icom FAQ: http://www.qsl.net/ 
>>> icom/ To
>>> support QSL/QTH.net: http://www.qsl.net/donate.html
>>>
>>>
>>> ----
>>> Your Moderator: Dick Flanagan K7VC: icom-owner at mailman.qth.net
>>> Icom Users Net: Sundays, 1700Z, 14.316 MHz
>>> Icom FAQ: http://www.qsl.net/icom/
>>> To support QSL/QTH.net: http://www.qsl.net/donate.html
>>
>> ----
>> Your Moderator: Dick Flanagan K7VC: icom-owner at mailman.qth.net
>> Icom Users Net: Sundays, 1700Z, 14.316 MHz
>> Icom FAQ: http://www.qsl.net/icom/
>> To support QSL/QTH.net: http://www.qsl.net/donate.html
>>
>> ----
>> Your Moderator: Dick Flanagan K7VC: icom-owner at mailman.qth.net
>> Icom Users Net: Sundays, 1700Z, 14.316 MHz
>> Icom FAQ: http://www.qsl.net/icom/
>> To support QSL/QTH.net: http://www.qsl.net/donate.html
>
> ----
> Your Moderator: Dick Flanagan K7VC: icom-owner at mailman.qth.net
> Icom Users Net: Sundays, 1700Z, 14.316 MHz
> Icom FAQ: http://www.qsl.net/icom/
> To support QSL/QTH.net: http://www.qsl.net/donate.html