[R-390] R390A OEM Line filter replacement

[jbrannig]

Many years ago I had my R390a hooked up to a PK-232 for fax and RTTY.I connected a dot matrix printer to the 232 for facsimile printing.POOF!..  .the printer is dead....lotsa head scratching......Finally realized the earth ground became disconnected with all the rewiring.The hot chassis of the 390, thru the 232, killed the printer circuit board.....Got a new printer and printed a lot of AP wirephotos and WEFAX......(And made sure the 390 stayed grounded)JimSent from my Galaxy Tab® A
-------- Original message --------From: Perry Sandeen via R-390 <r-390 at mailman.qth.net> Date: 7/16/19  7:57 PM  (GMT-05:00) To: r-390 at mailman.qth.net Subject: [R-390] R390A OEM Line filter replacement Yo Bubba Dudes!,The R390A OEM line filter is a dangerous and problematic because of its high undergrounded leakage. I'm posting a tutorial on the R390AFAQ site.Basically it shows one how to take out the OEM filter and replace it with the type you see on computers and newer test equipment. it's an easy fit as the new style filter fits on the original mounting screws.Also there are some notes on rewiring the the AC input to meet the current electrical safety codes.The problem stems from the old time practice that seems to be used on all the B/A receivers thatI've come across, both military commercial.What was done in the past was to put the fuse in one AC input lead and have the on-off switch wired in the other input lead.This can lead to a situation where the receiver is turned *off* and the fuse removed but there is AC voltage in wiring that can be touched while one has there fingers inside the receiver.  From experience I can tell you that this is not fun.When rewired in series, if the AC input fuse is removed, there is no danger of shock IF the AC input fuse holder wires are properly insulated. Silicon rubber is dandy for this.As a bonus, with the new filter installed, there is plenty of space for series wired CL-90 surge limiter and a parallel MOV.Regards,Perrier   ______________________________________________________________R-390 mailing listHome: http://mailman.qth.net/mailman/listinfo/r-390Help: http://mailman.qth.net/mmfaq.htmPost: mailto:R-390 at mailman.qth.netThis list hosted by: http://www.qsl.netPlease help support this email list: http://www.qsl.net/donate.html