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

[Doug Renwick]

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