[ICOM] IC-756PRO - Thumping, flickering screen, reset

[David J. Ring, Jr.]

A friend has a problem with a ICOM IC-756PRO:  It starts to thump when on 
QSK in CW mode, the screen has been seen to go temporarily blank for a 
quarter second or so and then return, but sometimes reseting the 
microprocessor and rebooting the radio.

The problem appears to be dependant on either r.f. power, or power supply 
loading as when the r.f. power output control is backed off to about 40 
watts the thumping cuts down.

The radio just started doing this yesterday - his antennas are snow 
covered - but SWR appears normal, switching bands and antennas does not 
change the problem.

Has anyone seen a similar problem before?  He has a 35 ampere Astron power 
supply that's 10 years old.

The '756 is about two years old.

What's your guess?  Is this a known problem, or is it likely the power 
supply has problems with regulation?

The problem with measuring AC ripple on the power supply with an 
oscilliscope is that it is difficult to filter out the r.f. from the running 
transmitter.

73

David Ring N1EA