Looking for some advice. I have two Atlas U33B HO engines with QSI Titan decoders. Both are programmed exactly the same as verified by JRMI read back. My problem is that on one the lower headlight on the nose comes on when track power is initiated and stays on regardless of direction and stays on bright when stopped also. The second engine's lights respond as programmed. Based on other threads I disabled the voice readback and analog. I also tried various changes to the light using the JMRI with no change, I even reset the decoder with the same result. When I removed the shells I see that the forward lights are wired separately but conect to the decoder through a single plug. My guess is that somehow the headlight is drawing power direct from track but thats only a guess. Am I missing some type of program option? These are my first and only QSI Titans. I have gone through the online 420 page manual until my eyes hurt. My other Atlas QSI's version 7 and 8 all program as they should on the program track. I am using NCE 1.65 powercab on the program track with JMRI. Any advice would be appreciated.
Marty C
Symptom is of the function output being blown. Each function 'output' is really the ground (the common, usually the blue wire, is positive) and actls like a switch to ground. In this case, it has failed closed, so as soon as power is applied, the light lights up.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
Randy,
That sounds reasonable but wouldn't the negative side of each forward light be wired to the same common and be affected the same?
Just so I have a grasp on this .... there is an upper headlight and a nose headlight. Are they both operated by a single LED for each ? And both of these lights tie together into a single two wire plug on the board ?
Mark.
¡ uʍop ǝpısdn sı ǝɹnʇɐuƃıs ʎɯ 'dlǝɥ
Well, if both LEDs on the good one are connected tot he same function wire, and both come on at the same time when the headlight is turned on, then yes, the other one should beahve the same. But if there is also another function that makes just the upper one flash or something, then still I'd say blown function. Because of the way the function 'outputs' work, you can connect the same LED to more than one function, and turning on either one would make it light, and turning on both would cause no harm to either the LED or the decoder because all you've done is turn on two switches in parallel that both connect to ground.
This applies to any decoder - want to make sure the headlight is always on regardless of any directional headlight settings? Connect both the white and yellow wires to the headlight.
If there is another function controlling the lower headlight - even if it was in parallel with the actual headlight function, there would be a third wire introduced into the lower headlight.
IF that is the case, either that function is on, or it's damaged and stuck on. Simplest fix would be to cut the third wire from the lower headlight.
Still need to know from the OP if they are connected to the board with a two or three wire connector.
Mark,
I need to look again but what I saw was the upper and lower lights each have separate LEDs with two wires coming out. The wires for both upper and lower go into a plug that looks similar to the type we see on mobile decoders and that is plugged direstly into the board. It's probably a pin type connector so that the function for each is programmed separately. The upper light responds to the headlight function and can be programmed but the bottom is on bright constantly. Does that help?
I removed the shell again. The lower light which stays on has a red and yellow wire from the light. The upper which responds properly has a red and blue wire coming out. The yellow and blue wires go into separate pins on the plug and the two red wires go into a single pin on the plug. there are six pins on the plug of which it appears three are being used. I am going to pull the shell on the other engine to check if the wiring is the same and will let you know.
Thanks to all for the help.
Update: The second engine is wired exactly like the first.
Second update. In keeping with check the simple things first, I pulled the plug, checked to make sure the wires were secure and not touching and reseated the plug. Eureka! The engine responds properly to all commands. By the way, I have been referring to the light as the lower headlight but it is actually the Mars light on the nose according to the JMRI. Live and learn.
Thanks to both you and Randy for the assist. Ihope I can return the favor sometime.
Well, we really didn't "help" you a whole lot other than ask questions ! Sounds to be just a bad connection in the socket. Glad to hear it was a simple fix.
Look at it this way, if you had not asked the right questions I probably would not have investigated the plug as closely. While you may not have provided a solution, you did provide valuable insight. In my humble opinion, thats what these forums are about.