I found numerous notes about putting an E-cap for keep alive in the old Soundtraxx DSD-100-LC decoders. Everything tells me where to put the negative of the cap but noting about the positive. I know electronics fairly well, but virtually nothing about decoder electroniucs and would hate to screw up a costly decoder. I searched on this forum's history and found things about lights and such, but not about the keep alive.
Can anyone tell me where the positive of the E-cap is soldered to?
Also, do I need the resistor diode addition to limit charge current so my NCE system doesn't think there is a short?
Thanks you. Very, very much appreciated for any help here. Ken
The below link is in some of the stay alive discussions at this forum. I and others have posted the link.
http://www.members.optusnet.com.au/mainnorth/alive.htm
Look for the largest cap right next to the full wave bridge. I prefer that method.
Marcus is also in the Yahoo SoundTraxx Group.
Rich
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If you ever fall over in public, pick yourself up and say “sorry it’s been a while since I inhabited a body.” And just walk away.
richg1998 The below link is in some of the stay alive discussions at this forum. I and others have posted the link. http://www.members.optusnet.com.au/mainnorth/alive.htm Look for the largest cap right next to the full wave bridge. I prefer that method. Marcus is also in the Yahoo SoundTraxx Group. Rich
Yes, that's the first place i went to and it doesn't have anything about the positive lead. Also, there is no cap at all to the right of the bridge as the bridge is at the end of the board.
I went to the Soundtrax forum before I posted the above request and couldn't find anything there either. I'll try posting the question to marcus there.
Thanks, Rich. Ken
kenkal richg1998 The below link is in some of the stay alive discussions at this forum. I and others have posted the link. http://www.members.optusnet.com.au/mainnorth/alive.htm Look for the largest cap right next to the full wave bridge. I prefer that method. Marcus is also in the Yahoo SoundTraxx Group. Rich Yes, that's the first place i went to and it doesn't have anything about the positive lead. Also, there is no cap at all to the right of the bridge as the bridge is at the end of the board. I went to the Soundtrax forum before I posted the above request and couldn't find anything there either. I'll try posting the question to marcus there. Thanks, Rich. Ken
You are right. It does not say so. YOU determine that.
I thought it would be obvious to you to get your multimeter and determine the positive lead. That is what i did. Not a big deal.
Some connect right to the output of the full wave bridge. Same point as the main filter cap for the bridge.
I never work on model railroad electrica/electronicsl without a multimeter.
I went back and looked. The blue wire is positive common. The 226 cap is the main filter cap. The bar on one side of the cap is positive. You could also use the photo right below that shows the positive and negative leads connected to the zener diode.
Your ohm meter would allow you to do a continuity check to determine where the bridge output connects to the main filter cap.
Great. Thanks, Rich.
I knew blue was common + for the lighting functions, but never thought it was a common positive as well (see how little I know about decoder electronics - -just enough to be dangerous.)
I learned electronics too long ago under vacuum tubes, then transistors, RTL, TTL, CMOS, etc. SMD's I have dabbled with a very little, but I'm never quite sure just what they can tolerate, such as from a multi-meter, so I'm a little skittish about damaging a decoder.
Thanks again, for the assist. Ken
Ok. I assumed you had a good knowledge of electronics.
I started with vacuum tubes in 1953 and went through everything up to now. Yes, I have scars on my finger tips.
Multimeter's will not damage a decoder if that is what you mean. I have three digital ones from Harbor Freight that do quite well. I stopped using analog multimeter's many years ago. I have an old one in a wooden case that is a collectors item, only.