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Discussion Starter #1
I have a bli mikado that has me absolutely stumped. I put this unit on the tracks and it runs extremely intermittently. I check it out and found it was losing power. I decided that the wheels need cleaned so I took them off and cleaned them so they were spotless. Now I have power but it’s only while the tender is going backwards. The second it rolls forward it loses all contact and quits. I tried this with the tender on and off the locomotive and it didn’t change anything
 

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When you say 'only when the tender rolls backward, do you mean connected to the engine but backwards, behind the engine ? Or, do you mean rolling it unattached in the opposite direction of the engine ?
It sounds like it's the first scenario where you likely have one or two trucks under the tender turned 180 Deg from where it's supposed to be. And is because the pickup wheels to the motor are in reverse polarity to the engine..
Turn a truck/s and see if that's the fix. The trucks on the tender usually have their pickup wheels on the same rail, their insulated wheels on the opposite rail, not mixed.
Yet, if this is a DCC engine then how would the connecter plug between engine and tender reach far enough to plug in way at the other end of the tender !! Or, is this an analog DC powered loco ? M
 

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Since the item makes sounds and moves, it has the correct polarity. If the polarity were reversed by rotating a truck or swapping ends of an insulated axle (which they have to be), you'd instantly short out the decoder and it would let out its magic smoke.

Do not reverse one of the axles or rotate a truck!!!
 

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Now I have power but it’s only while the tender is going backwards. The second it rolls forward it loses all contact and quits. I tried this with the tender on and off the locomotive and it didn’t change anything
until you said without the tender I would have suggested it's the drawbar connection and to wire between the loco and tender
 

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Discussion Starter #5
It’s a dcc and sound loco and the trucks can only go one way without being cocked. I cleaned wheels and pickups on the tender and I have a couple very small 0-6-0 tank locos that do just fine on my layout so it’s not a track issue. What I mean dis connected from the loco means I only have the tender on the track and I was listening for the sound to die. I found the decoder wasn’t completely seated in its sockets but that didn’t make any difference. The locomotive doesn’t pick up power at all which I’m not exactly happy about. Unless it’s through the driver springs.
 

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It's actually fairly common for the loco not to have power pickups. None of my 4 steamers do.

Sounds like you have a problem with the wiper assembly used to pick up power from the tenders wheels. Can you post a picture of it, one in which we can tell which end of the tender is the front?
 

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CTValleyRR, I don't think it's fairly common for locos to not have pickup wheels ! I'd say it's 99% rare. In all my decades in trains I have never ever come across a loco with no pick up !!
Firstly, diesels (having no tender) must have pickup wheels. And you'd be hard pressed to find a steamer where only the tender picks up ! I can accept a steamer having only its right side drivers picking up and its tender's left side picking up. But tender-only ? Are you sure your 4 steamer's drivers do not pick up ??! Are you saying that if you lift the locos a tad off the rails while tender is still on the rails, the drivers still turn ? I could be wrong. But I'd think that has to be a rarity..
 

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Discussion Starter #8
It has one set of the wheels on the tender picking up power and the other set picks up the ground. There is no continuity between the drivers on the locomotive and the tender
 

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It has one set of the wheels on the tender picking up power and the other set picks up the ground. There is no continuity between the drivers on the locomotive and the tender
what does "no continuity between the drivers on the locomotive and the tender" mean?

isn't the decoder in the locomotive connected to the locomotive frame and the insulated pin the drawbar connects to?
 

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Discussion Starter #10
It means none of the drivers pick up power. There are 6 wires that go from the loco to the tender. 2 for the motor 2 for the headlight and 2 for the firebox flicker led all power comes from the tender
 

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what does "no continuity between the drivers on the locomotive and the tender" mean?

isn't the decoder in the locomotive connected to the locomotive frame and the insulated pin the drawbar connects to?
That's what I'm getting at, too !! Of course the loco employs its drivers in the circuit ! This doesn't mean a tender can not have both sides making electrical contact That might exist. And I'm sure there are steam where only one side picks instead of both sides (rails). But If steam didn't have pick up at all, there'd be a lot of silver-colored plastic tiers and flanges on the drivers around town, and man what slipping that would cause, grades or not.
In fact the entire engine, tiers to smoke stack would be plastic/delryn, except the motor..
JS, are you also saying there are no wipers on the backsides of all their drivers ?
 

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Discussion Starter #12
There are no wipers at all. I have probe leads small enough to see if there is any form of electrical connection from the drivers to anything on the locomotive. There is none except to the frame nowhere else. So in theory if it was picking up from the drivers I should have connection to the tender plug. I have no connection from the drivers to the tender on any of the wires so there is no form of anything getting from the locomotive to the decoder in the tender.
 

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There are no wipers at all. I have probe leads small enough to see if there is any form of electrical connection from the drivers to anything on the locomotive. There is none except to the frame nowhere else.
wipers on the drivers on the loco are unnecessary since the drivers are metal, on metal axles riding in a metal frame.

on the opposite side, the drivers have a thin plastic piece insulating the tire from the wheel

you can check this with an ohm-meter


So in theory if it was picking up from the drivers I should have connection to the tender plug. I have no connection from the drivers to the tender on any of the wires so there is no form of anything getting from the locomotive to the decoder in the tender.
isn't the drawbar metal and doesn't it connect the loco and tender?
 

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There are no wipers at all. I have probe leads small enough to see if there is any form of electrical connection from the drivers to anything on the locomotive. There is none except to the frame nowhere else. So in theory if it was picking up from the drivers I should have connection to the tender plug. I have no connection from the drivers to the tender on any of the wires so there is no form of anything getting from the locomotive to the decoder in the tender.
I have many BLI steamers and they most definitely have electrical pickups on the drivers. If you doubt this, place one on the track, and then lift up the tender and see if it still makes sound. BLI steamers mostly use split frames and insulated axles, with electrical pickup through the axles and bushings to the frame halves. Running them on only tender pickups would be a very poor choice, since each tender truck only picks up one rail.
 

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Discussion Starter #15
It doesn’t make any sound no lights no movement nothing with it connected and the tender off the track. I can take one truck up off the track and it stops. Doesn’t matter which one it is either. The only place that loco is getting power is through the tender
 

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each truck must have insulated wheels on opposite sides.

make sure the wheels are clean and the pickups on the tender trucks are making good contact
 

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wipers on the drivers on the loco are unnecessary since the drivers are metal, on metal axles riding in a metal frame.

on the opposite side, the drivers have a thin plastic piece insulating the tire from the wheel

you can check this with an ohm-meter




isn't the drawbar metal and doesn't it connect the loco and tender?
I couldn't have said it any better..That's the next thing I was going to go to. And that is the bottom line..
Wipers, I just remembered, are needed on diesels because the plastic/delryn trucks/frames can't carry current in themselves ! The wipers behind the wheels intervene and carry the current into the the DC motor or DCC circuit board and/or split metal frame..
And that is what is going on..
Unpowered/not live drivers on steam would be a great rarity, not a commonality..
JS, Your drivers are live and carry current..If it were all left up to the tender, with such a short wheelbase there would be loads of stallouts over switches and diamonds; there being too stymied a current-gathering-range under the tenders..M
 

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Clearly there is a break down in the electrical path. You need to take the disciplined steps to isolate the problem.
Before that starts, we need to know if this is a new or used unit. If it is new you should seriously think about sending it back to where you got it or directly to BLI.
The first thing to do is a decoder reset to factory settings. You need to do this at least twice. These decoders are BB miniature computers and have similar issues as your lap top. They get electronic garbage that needs to be cleaned out. I have seen it wit brand new decoders right out of the package. This may cure the problem.
If your going to do the work, you need to connect a segment of track to a DC power supply.
Put the engine on that track and turn the control knob to medium. If nothing happens then the problem is in the power pick up side. If the sound comes on normally and does not cut out, that points to a decoder issue. The engine may run erratically because the supply has a PWM. Hold the tender in place and turn the power up an see if the engine running stabilizes. If so, the problem is with the decoder circuit operating on a DCC signal. Let us know what you learn if you get this far.
 

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Clearly there is a break down in the electrical path. You need to take the disciplined steps to isolate the problem.
one approach is to use a clip lead connected to one rail and some part of the loco or one of the decoder track leads to at least isolate it to one path between the decoder and rail
 

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The original poster, Jscullans, has stated that the tender
is source of all loco power, but that the tender has
limited power pickup...it has right rail pickup on one
truck and left rail pickup on the other truck. Also,
the tender is not as heavy as a loco.
These factors are likely the reason he is having loss of power to the loco.

I would suggest that he make sure that all wheels on
both tender trucks are metal and install wipers to the
backs of the wheels not previously used for pickup. It
also may be helpful to add weight to the tender for better
wheel to rail conductivity.
This will then give the tender all wheel pickup and should
solve the loss of power problems.

Don
 
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