[ICOM] Ailing IC-745 - any thoughts?

[Gary P. Fiber]

Richard,

When ever the IC-745 does strange things check the +8 volt regulator 
generally its at fault. This regulator is located on a small circuit 
card attached to the side in the bottom of the radio. Its quite small 
about 1" by 1" as I remember. Going from my rusty memory R1 on that card 
likes to change value a lot. Its 1/8 watt as I remember replace it with 
a higher wattage resistor. I do not believe it was designed as a 
resistive fuse as they almost never open up. Another problem could be a 
PA oscillation or an RF unit board problem. Sometimes a transistor like 
to go into oscillation on the RF unit and will cause this, generally its 
involved in the receive on the RF unit as I remeber.

A low +8 volts will make the logic do lots of strange things. I once has 
a caller who told me the radio would only transmit in the memory 
channels one and two even though all of the memories were programmed 
correctly, it was the +8 volts DC supply at fault. I doubt seriously it 
has anything to do with the ram card.

Gary K8IZ

Richard Peterson wrote:
> I want to thank the many folks who were kind enough to make 
> recommendations on where to ship my 745, should I elect to do so. 
> Thanks to everyone! It was very, very helpful.
>
> I have taken an initial look at the shop manual, and have thought 
> about repairing this on my own, but for right now, I am puzzled.
>
> On 160, 80 and 40 meters, it works perfectly. But on any bands above 
> that, and you key the mic, you get full output (just as if you hit the 
> key) on some really oddball frequencies. Further, this full output 
> occurs regardless of where the RF level pot is set. Plus, the tuning 
> control makes no difference at all. For example, on 14 MHz, the output 
> is fixed at around 24 MHz. You can spin the knob, but the frequency on 
> my counter does not change.
>
> This rig has several VCOs, as I recall ... but I am beginning to think 
> there is a logic problem.
>
> Any suggestions?
>
> Richard
> WB5NEN
>
> _________________________________________________________________
> Like puzzles? Play free games & earn great prizes. Play Clink now. 
> http://club.live.com/clink.aspx?icid=clink_hotmailtextlink2
>
> ----
> 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/
>
> .
>