I purchased a used DC Athearn bluebox F7 with flywheels. It runs smoothly. The previous owner changed the headlight to LED and he had soldered a flasher unit on the headlight. I didn't like it so I cut it out of the headlight leads (it had its own wires). Now the light doesn't flash, but it seems to sometimes flicker. It isn't a steady strong light. It doesn't matter what speed it is run; it still flickers. The wires are securely soldered. What's going on? Does it need a resistor?
Should already have a resister, (EDIT: I say this, as most LED's will not like a full 12V power supplied to them, so, if you have run it full-power and the LED still lights, most likely it has a resister.), sounds to me like it is a very slight intermittent power issue, not enough you notice on speed, but just enough to flicker the light. (Is it DC only still?) It may just need a good, thorough wheel and pick-up cleaning. Don't forget about the pick-ups between the trucks and frame. A good site for instructions on tuning up Athearn Locomotives is: http://www.mcor-nmra.org/Publications/Articles/Athearn_TuneUp.php
It covers things such as rewiring for better contact, (which I highly recommend BTW, though not 100% mandatory if sticking with DC.), and replacement wheelsets, along with adding DCC if you so desire to go that far.
Note: The points of interest here, for this issue, would be cleaning the strips and truck contacts, if you use those, or re wire as covered on that site, discussed about 3/4 down the page. And ignore the information on replacing the headlight, as that information is slightly outdated... And irrelevant as the prior owner already did that for you.
When you have the trucks off, clean and polish both the contacts on the truck AND frame... Cleaning only one side will not be helpful here.
Ricky W.
HO scale Proto-freelancer.
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The trouble is the electrical pick up. LEDs are extremely sensitive to interruptions in power. No doubt your engine still has the old style sintered iron wheels, which aren't the greatest for good contact. On top of that, you have a mechanic electrical connection between the trucks and the chassis - again, another weak spot for electrical continuity.
Make sure the truck / frame contact is clean, and polish the wheels until they look like chrome. It will help, but I wouldn't be surprised if you still get a bit of flickering.
Mark.
¡ uʍop ǝpısdn sı ǝɹnʇɐuƃıs ʎɯ 'dlǝɥ
Since there was some hacking out of the "flasher" unit, I suspect another possibility. Assuming the resistor is still inline to protect, it may be possible that when the flasher was cut out one wire was left loose and is now picking up half-wave power through the chassis. That can account for the flickering if only one half of the diode circuit was excised. Not saying this is it, but if the OP hasn't verified the circuits feeding power to the headlights this is a good time to do so.
I say this because I'm thinking the F unit has two headlights. It was common when this was the case for one to be a Mars or other similar type, while the other remained a steady-on headlight. The Rio Grande is one example of such a practice, so I'm guessing something similar is what the OP has on his hands.
If it does have just one headlight and it was rigged to simulate a Mars light, that would be rather strange.
In either case, check the wiring of what's left for any possibility of grounding through a loose wire to the chassis.
Mike Lehman
Urbana, IL
Wouldn't be "half wave power" .... this is a DC engine ....
If unit has the old style "Sintered" wheels they could be contributing to flickering.
Dick Haave