[ICOM] Icom R-8500 PLL Problem

[Ken Simpson, W8EK]

Thanks very much.

It appears that the problem is in the oscillator.  I turned it upside 
down and took it apart, and then fired it up to see what would happen. 
  Same problem.  With it turned on, I carefully banged on the 
oscillator module, and BINGO.  I heard white noise, as I had the 
squelch open and the audio turned up.  It stayed that way (that is 
apparently working, with the display no longer blinking) for a minute 
or two, until I turned the receiver right side up.  Now it is back to 
the way it was, and nothing seems to bring it back to life.  But at 
least that does say that it is likely in the oscillator area.

Time to put the scope on it, and see what goes (or does not go), and 
if the problem can be fixed easily.  Of course the easy fix would be 
to add the extra high stability CR-293 oscillator module, but at about 
$300, I think I will wait on that!

Thanks.

73,

Ken, W8EK


GGLL wrote, On 7/2/2011 12:53 PM:
> 	Ken, if the reference oscillator trimmer is faulty, the basic 
> oscillator would not work, and so the whole radio. Icom has many 
> problems with PLL and associated (which become dirty with time) trimmers.
> 
> 	Check the ref osc trimmer noting its position and turning it back and 
> forth a couple ot turns, although this may bring it to working condition 
> again, it is wise to replace the component as soon as you can.
> 
> Regards
> Guillermo - LU8EYW/W.
> 
> El 02/07/2011 11:00, Ken Simpson, W8EK escribió:
>>
>> Thanks, Adam.
>>
>> The problem I have is different that his (at least I think so), in
>> that it is simply the blinking display, that I think indicates a PLL
>> problem.
>>
>> I hate to send it out for repair, especially if it is something simple.
>>
>> However, if a PLL is unlocked, I would think it would only be one PLL,
>> and would work on some frequencies and not others.  That is why I am
>> wondering if I am missing a jumper, or something simple like that.
>>
>> Thanks.
>>
>> 73,
>>
>> Ken, W8EK
>>
>>
>> Adam Butler wrote, On 7/2/2011 12:32 AM:
>>> Not sure if this will help but I came across a post at radioreference
>>> today from a guy with a similar sounding problem. He did not go into
>>> detail as his post was to rant about shipping costs back to Icom but
>>> maybe you could ask him what he knows of the issue.
>>>
>>> The post is here:
>>> http://forums.radioreference.com/icom-receivers/215381-r8500-canadian-service-depot-finally.html
>>>
>>> At 05:33 PM 7/1/2011, you wrote:
>>>
>>>> I have an Icom R-8500 receiver that came from a silent key.
>>>>
>>>> It would appear that it has a phase locked loop problem.  The
>>>> frequency on the display is flashing all the time, regardless of what
>>>> frequency I put in.  That also means no audio, basically like the
>>>> squelch is fully on.
>>>>
>>>> However most every other function appears to work.  I did do a reset,
>>>> and that makes no difference.
>>>>
>>>> It is almost as if there is a jumper some place that is needed, but I
>>>> can not find any information like that.  Of course it is a bit hard to
>>>> ask the silent key about it!
>>>>
>>>> Any one have any suggestions?
>>>>
>>>> Thanks.
>>>>
>>>> 73,
>>>>
>>>> Ken, W8EK
>>>>
>>>> Ken Simpson
>>>> E-mail to W8EK at FLHam.net or W8EK at arrl.net
>>>> Voice Phone  (352) 732-8400
>>>>
>>>>
>>