Glenn, While it certainly does sound like your 7805 regulator has gone 'belly up' (you said it clicked relays at first and then stopped), I would revisit the resistance readings at the output pin of U5 as a first order of business. If you still fine >2k resistance on that line, then suspect the regulator - OTOH, if the resistance is significantly lower, find the short or solder splash - and remember to examine the soldering on the connectors too - yes, with a solder splash it could have worked initially and only became shorted when things were moved a bit.
73, Don W3FPR > -----Original Message----- > > Hi Guys, > I am building a K2 for a friend. I am at the first power test point in > the manual. The K2 has no display and no relays clicking on power up. I > have checked the basics and here is what I have found so far: > > I have gone over the front panel board, control board and RF boards with > my optivisor magnifier. All solder connections look good. All the > initial resistance tests on the boards checked out. I am finding the 5 > volt regulator on the control board U5 is only putting out 1.2 volts on > the output. The input is reading 13.5 volts. The input on U4 has 13.5 > volts and 8 volts output. Can I unplug the control board and power up > the 5 volt regulator by applying 13 volts to the input to the 5 volt > regulator with the control board un-plugged without hurting anything? I > suspect the 5 volt regulator is defective or something else is dragging > the voltage down. The 5 volt regulator is verified as a L7805 installed. > When the K2 was first powered up the relays started to click and then it > went dead. I am getting power through the resettable fuse and through > the power switch. > _______________________________________________ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
