[ICOM] IC-735 VCO Cap Replacement - ???

[Jim Hargrave]

Please enlighten us.

I have owned an IC-735 since 1986 and have never had a problem with the VCO
Caps.
Also, I have never seen any reports to that effect.

It has turned out to be one of the most reliable ICOM radios I have owned.
Mine has been opened only twice in all those years. Once to change the
battery and once to set the CI-V rate to 9600 baud.

   73's  Jim - W5IFP
    w5ifp at gvtc.com

> -----Original Message-----
> From: icom-bounces at mailman.qth.net
> [mailto:icom-bounces at mailman.qth.net]On Behalf Of
> harrytheham at verizon.net
> Sent: Monday, February 22, 2010 9:55 AM
> To: ICOM Reflector
> Subject: Re: [ICOM] IC-735 VCO Cap Replacement - ???
>
>
> They did.
>
> Harry WE1X
> Sent from my Verizon Wireless BlackBerry
>
> -----Original Message-----
> From: Doug Renwick <ve5ra at sasktel.net>
> Date: Mon, 22 Feb 2010 09:24:05
> To: 'ICOM Reflector'<icom at mailman.qth.net>
> Subject: Re: [ICOM] IC-735 VCO Cap Replacement - ???
>
> Correct me if I am wrong, but I don't believe the 735 had those bad caps
> that some of the other icoms had.
>
> Doug
>
> I'll run the race and I will never be the same again.
> -----Original Message-----
> From: icom-bounces at mailman.qth.net [mailto:icom-bounces at mailman.qth.net]
> On Behalf Of Michael, W1RC
> Sent: February 22, 2010 5:41 AM
> To: icom at mailman.qth.net
> Subject: [ICOM] IC-735 VCO Cap Replacement - ???
>
> Thanks for the replies and information.  I have performed the
> replacement with limited success and I am now scratching my head
> trying to figure it out.
>
> When I started this project the radio worked very well on 75 and 40
> meters.  The problems were with the higher bands.  It was dead above 15
> MHz.
>
> I replaced the plastic PLL trimmer caps C37 C45 C52 and C59 with the
> ceramic versions purchased from ICOM.  I was able to adjust the two
> 12 pF caps, C37 and C45 for a reading of 6.5 Volts measured at R108
> but my meter did not show any change in voltage when the two 6pF
> trimmers caps were turned.
>
> After reassembling the radio it would appear that the original
> problem has not been resolved.  The radio is still dead above 15 MHz.
>
> I did not replace C138.  Since this appears to be a common control I
> do not think it is the cause of the problem.
>
> Most of my troubleshooting and repair experience in over 40 years of
> hamming is on vacuum tube equipment.  Any ideas or suggestions as to
> what to look at next will be gratefully appreciated.
>
> 73,
>
> Michael, W1RC
>
>
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