Jamie, If the diode is in series with the power line (as a reverse voltage protection diode), and if the unit is being fed with a positive voltage, the anode lead should be connected toward the +12 volt supply side. Since you said there was voltage on the cathode but none on the anode, it would seem to me that the diode may be installed backwards - and that would produce the result you are observing.
73, Don W3FPR > -----Original Message----- > > I know this has nothing to do with Elecraft gear, but having built the 3 > radios, I knew this is the place to come for experienced > troubleshooters. I > have an old JPS NIR-12 DSP unit, that, after applying power, decided to > quit. The power lamp will not now light. This unit does not have > a fuse. So > I decided to get out the DVM and attempt to see what's going on. > > > > The DC power jack goes to a T-network consisting of two 0.1 uf caps with a > bead inductor before going to a DPDT switch. Beyond this is a 0.1 > uf cap in > parallel to ground and then a series 1N4004 rectifier diode to a 1000 uf > electrolytic capacitor in parallel to ground. From there it branches to a > couple of voltage regulators to get different voltages. When voltage is > applied, I get 13.7 volts on the cathode side of the diode, but > zero on the > anode side (and beyond). I initially thought that this diode was at fault > and desoldered it and replaced it with another 1N4004. But, alas, this was > not the culprit. I desoldered the 1000uf electrolytic, but my capacitance > meter reads it correctly at 1000uf. > _______________________________________________ Elecraft mailing list Post to: [email protected] 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
