Frame shorting out to the rails shouldn't fry a decoder. It could possibly happen if a derailment forces the non-grounded wheel up into the bottom of the frame. Short across the rails, but nothing flowing through the decoder.
The troublemaker is the Proto 2000 S1 switcher (and the similarly built Atlas S2 switcher) where the frame is one side of the motor but the trucks are isolated from the frame. Completely opposite Athearn BB. In these locos, neither wheel or wheel wiper touches the frame, so it SEEMS safe enough. However, out of the box, the lower motor brush is connected to the frame, and the oriange wire to the motor from the factory board is just screwed to the frame. Pull the factory board and test, neither motor brush is connected to the rails, so it should be OK. Right up intil the loco derails oon a switch and one of the wheels (doesn't matter which side, here) gets pushed into contact with the frame. Now you have track power on the motor side of the decoder - that fried the decoder for sure.
The issue here is possibly the extra wipers touching the frame, or just the sintered iron wheels making pooor contact, however that typically does not cause the DCC system to indicate a short. Usually that just makes very small sparks (sometimes you can see them in a darkened room with the loco rolling along just fine). Definitely suspect the wiper or the wiper mounting. If your phone, or maybe camera, can do video AND also do somewhat of a slow motion, filming the locos and then playing it back at slow speed might help pinpoint where the sparks are coming from.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
Hello all,
mbinsewiI've never had to isolate the trucks. I make sure that connection is clean, and I tap a hole in the frame for a 2-56 screw, and attach the black wire to it.
As I said before, the older BB's use the frame as a conductor.
On some conversions I have done the same thing you have, continue using the frame as a conductor.
However this can provide a catostrphic potential for the frame to short out on the rails and fry the decoder (don't ask how I know, but I know).
From what I understood from the OP is that he was using both the frame and...
JRPI added extra "pick-up" contacts to each truck wheel using .008 phosphor bronze wire...
I suspect this secondary set of pickups the OP added, along with the primary pickups through the frame, are causing an intermittent short- -with the possibility to fry the decoder.
Glad to hear you haven't fried the decoder.
You only need to use one path from each rail to the motor, either through the frame or wires soldered directly to the sides of the trucks and isolating the truck contacts.
Either works but not both.
I use Kapton tape with great result too. I prefer a physical gap between electronic components with Kapton tape.
This way there is little possibility of the tape being worn through and creating an electrical path. Same thing for liquid electrical tape and paints.
Hope this helps.
"Uhh...I didn’t know it was 'impossible' I just made it work...sorry"
Just so you know, Athearn makes a high performance motor with flywheels for DCC (part # 84086). It does not have the two prongs on the bottom of the motor, but instead the copper flange on both top and bottom is flat and you can solder your gray and orange wire to them respectively without having to cut off or bend the raised clips like the old standard motors. I like to remove the flange and solder with it off the motor, then replace it to avoid any excess heat. Yes, you still need to be carefull to not let the small spring or brush pop out and you still need to isolate this motor. I use Kapton tape as I have had good luck with it.
jjdamnitOn older BB's, in addition to isolating the motor from the frame, the trucks needed to be isolated from the chassis.
I've never had to isolate the trucks. I make sure that connection is clean, and I tap a hole in the frame for a 2-56 screw, and attach the black wire to it.
Athearns orientation on the trucks, is the side with the tall contact (look at JJ's link to the truck) on the egineers side, both trucks, front and rear. You can put them on the conductors side, just make sure both trucks are orientated the same way. Putting that taller contact point on the conductors side, just reverses forward, and backward loco movement.
Maybe take the shell off of the locos you have successfully converted, and follow your steps, maybe your doing something different.
And like posted earlier, the motor MUST be isolated from the frame.
Mike.
EDIT: Another thing I do is replace the older sintered metal wheel sets with the new NS wheels. Athearn has them, for 4 and 6 axle locos, they come complete, with brass bearing blocks, and gears. Just check the wheel gauge, and drop in place.
My You Tube
Good information here, although I knew some of it, but not all. I'm going to make sure I isolate all power sources other than the orange and gray. Will let everyone know the results. Thanks for the additional information.
Cheers
JRP
Thanks Mel. The trucks and wheels are new and thus very clean and shiny. I just installed the bronze wires the other day...also clean. Unfortunately I have not been able to run it long enough to get it dirty.
JRPDecoder is isolated...
Most decoders come with a shrink wrap type covering which provides electrical isolation from the solder contact points on the PCB to anything metallic internally; specifically the frame.
JRPHowever, I removed the pickup wires from the trucks to test if the unit was still getting electrical pickup using just the chassis pivot points on the trucks, and ran it again getting the same start and stop.
Sounds like the motor is not isolated.
OK...
Please excuse me in advance if I get too basic. I am not trying to be condescending, again, I apologize if I come off that way.
The Athearn Blue Box Direct Current locomotives motor received power from two paths.
One path is from both sets of wheels on one side to a contact between the trucks and the frame.
From here the frame becomes the electrical path.
The motor has two prongs on the bottom of the motor that complete the path from frame to motor.
Often these are overlooked. You can press these prongs down and cover with Kapton tape.
You can swap the top cover for the bottom, be careful of the magnets and springs!
The path on the other side of the trucks goes to a bracket above the gear tower.
This then goes to energize the other side of the motor.
When you install a DCC system the motor needs to be isolated from all power sources other than the two motor control wires from the decoder; Orange, Gray.
On older BB's, in addition to isolating the motor from the frame, the trucks needed to be isolated from the chassis.
I choose to cut these contacts off and solder wires directly to the frames.
This isolates the trucks from the frame so the only power from the wheels are from the newly installed wiring; Red, Black.
Now all the components; not just the decoder, are electronically isolated.
Down in the trucks and wheels. Decoder is isolated, not hot and not fried (and I hope I don't)
Hi guys,
I am using the phosphorus bronze wire to get better electrical pickup, but at the same time I have the chassis "pivot points" connected and sitting on the trucks. I have not fried my decoder as it is isolated from the chassis using Kapton tape. I only get "short" readings as the unit travels down the test track and occasional sparks fly below where the wheels and trucks are. The decoder is not hot either.
However, I removed the pickup wires from the trucks to test if the unit was still getting electrical pickup using just the chassis pivot points on the trucks, and ran it again getting the same start and stop. Would it help to cover the pivot points with a resister type paint or tape and just rely on the pick up wires??
I'm also using metal Kadee couplers, but with the plastic draft gear boxes. BUT, one is connected to that chassis "metal shelf" with a screw. The other coupler is glued to the metal shelf. Note: I was able to motorize another dummy GP38 and an old Athearn dummy GP35 with no issues what so ever. I was hoping I could do the same here. Need to check my couplers on the others.
I do have another empty GP38 chassis and am thinking maybe I should try to install in that one, but using the ideas you guys suggest here.
Thanks and will let you know.
Posting tip: you might consider using smaller blocks of text rather than one huge block.
It makes it easier to understand what is happening.
JRPCould it be the old chassis?
Older Athearn Blue Box locos use the chassis as a conductor to power one side of the motor.
JRPI cleaned and polished the truck pivot on the chassis to be sure I covered the bases.
Are you using the chassis as a conductor?
If you didn't electrically "isolated" the motor from the chassis I would suspect a fried decoder rather than sparks. But you do describe erratic running.
Could the motor be making intermittent contact with the frame?
MisterBeasleyJust a guess, but are you using Kadee or other metal couplers, and are they isolated from the frame using plastic draft gear boxes or other insulation techniques?
I would also consider this possibility.
Both can be tested with the continuity function of a meter ("beeper").
Hope this helps .
Just a guess, but are you using Kadee or other metal couplers, and are they isolated from the frame using plastic draft gear boxes or other insulation techniques? If not, you could occasionally be getting shorts between this engine and others, or between the engine and rolling stock, because the couplers are providing an intermittent electrical path.
It takes an iron man to play with a toy iron horse.
I have sparking issues with an Athearn BB dummy locomotive that I recently motorized. In a nut shell I have done the following: added a new Athearn motor, new wheels, new trucks, new worm gears and drive shafts, and wired to an Econami 200 decoder. The loco is a GP38 frame, and Athearn assured me that their older BB frames like mine have not changed to a different design (with exception to Genisis I believe). The decoder is isolated from the frame. The trucks and wheels are new and my track is very clean using alcohol and a track cleaner made of masonite. Yes, the wheels are in gauge. I added extra "pick-up" contacts to each truck wheel using .008 phosphor bronze wire knowing that older Athearn loco's are not known for excellant electrical pickup. On my 8 foot test track, the engine stalls and starts, but sometimes runs the whole length up and back without a stop. But I check to see if my Throttle (DCS-50) is showing a short, which is does every few seconds or so, and sometimes I see sparks on the reverse as I slow to a stop. I removed the wires and ran without them, but still had issues. I have other BB units with the pickup wires installed and NO ISSUES whatsoever. Could it be the old chassis? I cleaned and polished the truck pivot on the chassis to be sure I covered the bases. The only thing I have not done yet is add weights. Any thoughts here?