OK, here is the latest.
I desoldered all four pick up wires from the decoder teminals and reverse them, connecting the front pick up wires to the rear decoder terminals and the rear pick up wires to the front decoder terminals.
Once I did that, the front trucks were working and the rear trucks were not working.
So, that tells me that the problem is one or both of the front terminals on the decoder.
There is power being picked up by all four trucks and delivered to the decoder, but the front terminals of the decoder are not sending power to the motor.
Am I testing and reasoning correctly, or am I missing something?
Rich
Alton Junction
I am pretty convinced it's NOT the decoder. If the decoder was bad, it wouldn't run at all The only possible way it could be the decoder in this case is if one of those end to end traces is somehow cut, somewhere between where the front truck wires connect and where the rest of the circuit taps off this power to operate the decoder. Not too likely, at least by accident. And if this were the case, there would be no continuity betwwen the left rear wheel and left front wheel, or right rear wheel and right front wheel, as those decoder traces sit right in the middle of all that. I believe you have a pickup problem between the wheel and the pickup itself, where you have just soldered the wires.
Do you have a headlight hooked up? Does it go out when you lift the rear truck off and the motor stops? Witht he rear truck insulated from the track, try wiggling the front truck around and see if the light flickers on or the motor gives a little jump - that would pretty m,uch prove intermittant pickup.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
zstripe Mark and Rich, It states,putting a drop of oil,right in my maintenance instructions,that I got with all three of my Genesis SD70/75M's,from Athearn,sometimes,it does not hurt,to read those things,once in awhile. The pick-up,is the same as the F7's,,except, again for the third axle. Cheers, Frank
Mark and Rich,
It states,putting a drop of oil,right in my maintenance instructions,that I got with all three of my Genesis SD70/75M's,from Athearn,sometimes,it does not hurt,to read those things,once in awhile. The pick-up,is the same as the F7's,,except, again for the third axle.
Cheers,
Frank
Frank, I wasn't challenging your statement, but I was asking who "they" were. I now assume that you meant Athearn.
Interestingly, there is no such statement in my Athearn Genesis F7 Santa Fe owner's manual about oiling the axles or the slots that they fit in on the trucks.
Rich,
Below is a couple paragraphs from another thread I copied and pasted here that might be your problem. It sure fixed all my problems with my 6 Genesis units I have.
Barry
Electronics and DCC / Athearn Genesis F-Unit Fix
The wheelsets have a split axle with a plastic gear in the middle. The axle ends extend into a metal bearing plate in the sideframes. This bearing plate should transfer both the electrical current and weight of the locomotive between the wheels and the trucks. The wheelsets fit into a gear tower and are held in place with a plastic plate that snaps onto the bottom of the truck. The two plastic sides of the gear tower have slots for the axles. The problem is that the slots are NOT DEEP ENOUGH. The plastic part of the axles rubs on the top of the plastic gear tower slots, causing the axles ends to "float" in the bearing plates resulting in intermittent electrical contact.The solution: Remove the sideframes and wheelsets. Take a small round file and file the axle slots in the gear tower to make them deeper. (You might want to completely disassemble the trucks to do this. I didn't bother since a few plastic filings shouldn't be too harmful.) Once this was done and the trucks were reassembled the problem was GONE! This fixed all my Genesis F-units.
zstripe Rich, I don't have Genesis F7's,but I do have three SD75m's and the pick-up should be the same,except of course for the third axle, but the whole end of the axle picks up power from the bar,not just the pointed end,they suggest putting a light drop of oil,where the axle goes into the bar and get rid of the wire locks and solder the wire to the bar. Cheers, Frank
I don't have Genesis F7's,but I do have three SD75m's and the pick-up should be the same,except of course for the third axle, but the whole end of the axle picks up power from the bar,not just the pointed end,they suggest putting a light drop of oil,where the axle goes into the bar and get rid of the wire locks and solder the wire to the bar.
I agree with soldering all wire connections, but don't put any oil in a location designed for electrical continuity (unless of course you use electrically conductive lubricant, and even then I wouldn't recommend it).
I've had more than a few engines develop poor electrical pick up, and the problem was ultimately found to be lubricants in the axle contact strip causing a contact problem. Dry the axle tips and ream out the holes in the contact strip with round wooden toothpicks until no more black showed and the problem went away.
Mark.
¡ uʍop ǝpısdn sı ǝɹnʇɐuƃıs ʎɯ 'dlǝɥ
zstripe Rich, I don't have Genesis F7's,but I do have three SD75m's and the pick-up should be the same,except of course for the third axle, but the whole end of the axle picks up power from the bar,not just the pointed end,they suggest putting a light drop of oil,where the axle goes into the bar and get rid of the wire locks and solder the wire to the bar.
Frank, who is "they"?
Rich.
It is possible but unlikely that the decoder traces from on end to the other is broken. I would solder one end to the other with a piece of decoder wire. This in essence is extending the front truck pickups to the rear truck pickups. Cold solder joints can be the main problem.
Pete
I pray every day I break even, Cause I can really use the money!
I started with nothing and still have most of it left!
Is it possible to solder jumper wires between the rear truck and the front truck? Then solder these to the decoder terminals for the rear truck. This is the route that I would go just to see if everything worked.
Chuck - Modeling in HO scale and anything narrow gauge
zstripe Probably would be a good idea,to test pick-up,from the wheels,that pick-up power to the wire that goes to the decoder also. The wheels could be picking up power,but not transferring to the pick-up bar.
Probably would be a good idea,to test pick-up,from the wheels,that pick-up power to the wire that goes to the decoder also. The wheels could be picking up power,but not transferring to the pick-up bar.
Frank, that is a good point, and I have wondered about that. The source of the continuity at that point is the pointed ends of the axles. That is a pretty small contact point, so I wonder whether that could be the problem.
With the rear trucks off the rails, and the motor not spinning, I have applied pressure to the side frames of the trucks to see if better contact could be made with the wheels, but no luck.
Not sure if that could be the problem or not.
My curiosity got the best of me, so I went down to the layout and soldered the pick up wires to the copper strips on the front trucks, after removing those plastic clips.
Nothing!
The front trucks still do not work. With the rear trucks off the rails, the motor stops spinning.
Foolish me, but I am convinced that the problem is with the decoder.
I suppose the next step would be to desolder all four pick up wires from the decoder teminals and reverse them, connecting the front pick up wires to the rear decoder terminals and the rear pick up wires to the front decoder terminals. If the rear trucks no longer were working but the front trucks were working, that would confirm a problem with the front terminals on the decoder. Agreed?
OK, thanks, Randy.
Before I go any further, I am going to solder the wire connections to the copper strips on the trucks. If that solves the problem, I will be both delighted and relieved.
I did not realize that using an ohmmeter on the decoder could fry it. Is that true even with power off to the layout?
To answer one of your questions, if I lift the front trucks off the rails, yes, the motor keeps turning, thanks to power from the rear trucks. But, if I lift the rear trucks off the rails, the motor stops turning, leading me to question whether power is being picked up from the front trucks.
When I mentioned that I was lifting the trucks off the rails, I actually did rest the trucks on a light piece of cardboard, not holding the end of the loco up in the air. Sorry for my less than precise description of how I was doing that.
Just pressing the meter's probes to the trucks or the decoder could be pushing down enough to get a better contact.
It's still valid - what happens if you take the front truck off? If the pickup from the front is faulty, but the rear is ok, it should keep running. If it stops, the same way as taking the rear truck off, then what you actually have is a situation where one truck is working for the right rail, and one for the left. Also try using a piece of paper rather than actually lifting, you could be lifting enough to break contact for the other truck.
You have to measure the power to the motor with the volt setting. Do NOT use the ohms setting on a meter into a circuit like a decoder, it's applying voltage to get that resitence an continuity reading, and applying voltage to the motor terminals of a decoder is a good way to fry it.
If the loco runns normally otherwise - it's not the motor outputs.
Use the AC volts setting and measure the volts at the decoder terminals where the trucks connect. You should see the same as track voltage.
Did you ever,remove the front truck wires from the decoder and then test for continuity? You may find that is your problem, if you do not remove,the wires,you will get continuity,because of the connection to the decoder. You have to isolate,the truck. You don't mention if you ever did that.
One other question, guys.
Is there a way to test that power is being tansmitted from the decoder terminals to the motor.
Would a continuity test establish this?
Pardon my ignorance, but I ask this because if the four power pick ups are working correctly, that will bring me back to the question of why, when I lift the rear end of the loco completely off the rails, the motor stops running.
cacole If you haven't already done so, SOLDER the wire connections at both ends -- to the truck side frames and to the decoder. This will eliminate faulty pickup due to those little plastic clips not making good contact. I have used close to 20 NCE DA-SR decoders and 80 D13SRJ and have never had a bad one, so I seriously doubt that your problem is related to the decoder.
If you haven't already done so, SOLDER the wire connections at both ends -- to the truck side frames and to the decoder. This will eliminate faulty pickup due to those little plastic clips not making good contact.
I have used close to 20 NCE DA-SR decoders and 80 D13SRJ and have never had a bad one, so I seriously doubt that your problem is related to the decoder.
cacole, I will follow your advise and solder the connections on the trucks. I had previously soldered the connections on the decoder terminals.
From what others are telling me, the ohmmeter continuity test is not necessarily a valid indication of sufficient power from the rails to the decoder.
I will report back on the results.
Soo Line fan Rich, The ohm test is just an okay test. Better than nothing. This is why: Connect a ohm meter to both ends of a wire and record the value. Now clip away at the strands while the DMM is still attached. The ohm value will not change much until you reach the last few strands. So, while continuity is present, the voltage supplying potential of the wire is not really known.
The ohm test is just an okay test. Better than nothing.
This is why: Connect a ohm meter to both ends of a wire and record the value. Now clip away at the strands while the DMM is still attached. The ohm value will not change much until you reach the last few strands. So, while continuity is present, the voltage supplying potential of the wire is not really known.
Jim, thanks for that info. With my limited electronics knowledge, I thought that the ohmmeter test for continuity was the foolproof way to proceed. But, apparently not.
I did perform some additional continuity tests, for what it is worth.
With power off to the layout, I did test continuity from the rails to the decoder. I also tested continuity from the rails to the opposite ends of the decoder, for example, front right rail to rear right terminal on the decoder. I also tested continuity from one end of the decoder to the other end of the decoder to verify that the traces carried current from one end of the decoder to the other end. All of these tests showed continuity.
But, as you say, maybe these tests don't really confirm that sufficient power is being picked up from the rails to the front terminals of the decoder.
rrinker But if you lift the front truck off and keep the rear one on - does it run? On those types of decoders, there should be a relatively heavy trace on the circuit board going from end to end linking the outer connecting terminals, connecting the left front to left rear, adn right front to right rear. That fact that you can see continuity between one end of the loco and the other seems to confirm that this connection is intact. If lifting the front truck off does not cause it to stop, I'd check that continuity again. If it runs otherwise, it could be that lifting the rear truck off is binding the universal joints in the drive linakge. I suspect however the real culprit is the generally poor power transmission system Athearn continues to use.
But if you lift the front truck off and keep the rear one on - does it run? On those types of decoders, there should be a relatively heavy trace on the circuit board going from end to end linking the outer connecting terminals, connecting the left front to left rear, adn right front to right rear. That fact that you can see continuity between one end of the loco and the other seems to confirm that this connection is intact.
If lifting the front truck off does not cause it to stop, I'd check that continuity again. If it runs otherwise, it could be that lifting the rear truck off is binding the universal joints in the drive linakge. I suspect however the real culprit is the generally poor power transmission system Athearn continues to use.
Randy, thanks for those comments.
The problem is with the front truck. If I ift the rear end of the loco completely off the rails with power on to the layout, the motor stops running. I don't see any mechanical problems or binding problems with the motor assembly, linkages, or gears. To me, it seems to be clearly an electrical continuity problem.
The test light method which is loading the circuit, is better but the problem is how bright is a light supposed to be?
richhotrainWith the rear truck off the rails, I put a pair of wires connected to a 12 volt incandescent bulb onto the terminals of the decoder where the pick up wires from the front truck connect. The bulb lights. So this would seem to indicate that the pick up wires are carrying power from the rails to the decoder.
Now, lets try an even better way. While using the test light method you used above, measure track voltage and also decoder input voltage where you are attaching the test light. The difference between track voltage and decoder input voltage is the amount you lost through the pick up path.
This is a loaded test, aka voltage drop test. and is always preferable to just a ohm test. The test light loads the loco pickup circuit and the voltage meter measures the voltage drop loss.
Jim
If lifting the front truck off does not cause it to stop, I'd check that continuity again. If it runs otherwise, it could be that lifting the rear truck off is binding the universal joints in the drive linakge. I suspect however the real culprit is the generally poor power transmission system Athearn continues to use. What was pretty reliable on the Blue Box locos is much less so after they modified it to add things like the plastic spacer so you can;t see the metal truck frames. I have a RTR RS3 that needs the plastic filed down a bit, the metal bushings on the wheel shafts ens up riding more on the plastic than on the metal behind it, and metal to plastic does not conduct electricity very well.
OK, guys, bear with me because electronics is not my strong suit.
I took the loco off the layout and pulled the side frames from the front truck exposing the wire on each side frame. I put the probes from an ohmmeter on both ends of the wire and got continuity.
I examined the truck assembly to try and understand exactly how power is transferred from the rails to the decoder. The wire is held in place on a copper strip by a plastic clip, That copper strip extends over both wheels on the side of the truck. The metal wheels touch the copper strip at the pointed ends of the axle. So, if I reason this correctly, the metal wheels sitting on the rails pick up power and transfer it through the copper strip, up through the wire, to the terminal on the decoder.
Assuming that is correct, I re-assembled the truck and reconnected it to the loco. Then, with power off to the rails, I put the loco back on the layout, I slipped a piece of cardboard between the rails and the rear truck so that only the front wheels were making contact with the rails. Then, I repeated the continuity test by touching one probe to the rail and the other probe to the decoder terminal. I did this for both trucks and there was continuity from each rail.
So, it seems to me that the problem is with the decoder. Back in June when I most recently noticed this power pick up problem with the front truck, I inquired about a faulty DA-SR decoder on the Yahoo NCE-DCC forum and basically got shouted down when I suggested that perhaps the decoder was faulty. LOL Well, excuse me. So now I am wondering about something else. If the DA-SR decoder was good "out of the box", is there a chance that the motor on the Athearn Genesis is causing problems? I don't mean mechanical binding, but rather causing some electrical malfunction with the decoder.
The problem seems to be intermittent and it occurs on both of my F7B units.
Any thoughts, comments, criticisms?
I would say your last sentence,in your post. If you go back to another one of your posts dated, May 23rd,you will find out that.they had issues,with they're truck pick-ups and you replaced the whole truck. The title of that thread was,How to remove the Front truck,on a Genesis F7A..Have fun!!
Frank, with all due respect, I went back and re-read that entire thread before I posted this new thread.
Re-reading it only added to my frustration.
This has been a recurring problem since 2009 when I first noticed it. It seems to be intermittent from the notes that I have kept about this power pickup issue.
Sometimes, both trucks are picking up power, sometimes one truck is not picking up power. Or is it?
It occurs, intermittently, from time to time with three of the four Genesis F-units, both of the B units and one of the A units.
Complicating the problem is my use of DA-SR decoders.
Is it the decoder or is it a faulty pick up wire from the truck? It is always the front truck, no matter the loco.
I gues what I have to do is strip down the two B units and re-work the power pick up wire.
I love this Genesis consist in spite of all of the problems related to the pick up issue. Some friends have advised me to dump the entire consist, but I don't want to do this. I want to solve the problem.
What is the best way to test the power pick up wires? Remove the entire truck assembly from the loco and test it on the bench?
Argggggh.
http://cs.trains.com/mrr/f/744/t/217793.aspx
richhotrain Is it a decoder problem where power is not transmitted from the terminals to the motor?
Is it a decoder problem where power is not transmitted from the terminals to the motor?
Since the loco runs with the rear truck on the rails, I would say no. This might be a dumb question, but have you checked the wires coming from the front truck since that truck does not seem to supply power to the decoder? I have seen it where the wires break loose on one end or the other and need to be reattached.
Not sure about the bulb situation. I've never checked one that way. I have used a ohm meter numerous times and that helps tremendously.
What you need is a VOM that has an audio continuity test or use the resistance settings to trace between each side of the truck to the location where the wire connects to the decoder, with the locomotive OFF the track, to confirm whether the rear truck is actually passing power to the decoder.
Well, that is the reason for the question, Frank.
What confuses me is the fact that the bulb lights.
What I don't understand is how to confirm whether or not power is being picked up by the front truck and transmitted to the decoder.
Your reply has not gotten me any closer to an answer.