Bachmann 2-8-4 Berkshire/Kanawha in stock at M.B. Klein

[Rasputen]

Mine definitely does not get along with my MRC DC power pack.  It will jerk to a stop and then suddenly re-start.
Here are a few assembly issues I found:

First, I noticed that the phosphor-bronze wires in the draw bar are not in contact with the post on the chassis of the locomotive.  These seem to be redundant however, since there are two wires connecting the left and right halves of the chassis with the tender at the electrical connector.


Then, I found that one of the tender pickups is bent up too high, so that the rear tender truck will lose contact when it pivots:


I also found that the right side locomotive chassis wire was pinched by the rear screw so badly, that the insulation is broken along with some of the individual strands of the wire.  You can also see the black piece that is supposed to keep the wires safe, but in this case it was ineffective:


I also found overspray of the white driver paint on the driver surface.  It doesn't look like much in the photo but it is much worse in person:


I am going to clean all of these issues up, and make a jumper to take the place of the decoder. 

[mmagliaro]

I doubt it has anything to do with the MRC power pack.   A DCC engine, running on DC, will jerk to a stop and go through
a "reset" if it loses contact with the rails.   If you correct that bent pickup finger in the tender, and make sure
all the other pickup wheels are actually working, I bet that problem will go away.    If you are planning to only use this
on DC, I agree with your plan to pull the decoder and put in a jumper.  The engine will be much more responsive that way.

[Rasputen]

I made a jumper for the DCC connector and it runs at an acceptable level on DC.  I think that most of the power pickup is coming through the tender wheels, probably due to all of the oil on the mechanism.  The low speed performance is not great, and I have to use an 0-5-0 nudge or some pulse injection to get it moving sometimes.  More weight in the tender might help this.  I do get that coffee grinder sound at low speeds sometimes, similar to the heavy 4-8-2.  The top speed is pretty low compared to most N scale locomotives, and once it is at a moderate speed it is fairly smooth and quiet.  Now I'll have to figure out how to get the front and rear lights working again...

[peteski]

So Chris, does it have a coreless motor or not?

As far as needing to have the DC throttle up over 50% to start moving, that is nothing new or odd. That is normal for all the DCC sound decoders.  They need fairly high voltage for the sound processor/motor control to initialize and operate.   After all, their main purpose is to operate on DCC.

[Chris333]

To get to the motor I have to remove all the valve gear. And since there is no reason (yet) to crack it open, I'm not. It is shiney silver metal with a pathetically small flywheel. Sure looks like the 4-6-0 motor to me, but that is only looking through the frame slot.

[peteski]

To get to the motor I have to remove all the valve gear. And since there is no reason (yet) to crack it open, I'm not. It is shiney silver metal with a pathetically small flywheel. Sure looks like the 4-6-0 motor to me, but that is only looking through the frame slot.

Um, that is not a very tuneup-friendly construction.  Looks like we'll have to wait until someone else cracks one open.

[wcfn100]

Looking at the diagrams, it's got the same motor as the S4.  It's not the same as the 4-6-0 if only because it has a dual shaft.

Jason

[victor miranda]

at least I see why people are having pickup issues.

somewhere out there is a soul who thinks
that a little stiff tab off a PC board will give pick-up service.

IT DOES NOT WORK!!!

I am tired of seeing this.

the problem is exactly the same at the CC 2-10-2.
and at least one possible fix is the same.

file notches into the truck thumbs and
set MT coupler springs on the notches

victor

[sizemore]

Taking Chris' lead I tinkered with the quartering on the last driver. I was watching the side rod motion, and the D3-D4 rod "flexes" like the pencil test in relation to the D1-D3 rod. So after about three tweaks I think I have it almost right. Once in a blue moon it will hitch. I also reamed the rod holes on the D3-D4 to give it a hair more play.

The S.

[Chris333]

I didn't quarter the rear driver itself. Instead I matched it with the 3rd (traction tire) driver and that seemed to work. It was close before and run good by itself, but pulling a train load it didn't. As it is now I ran it with a train for 1/2 hour so I'm happy enough with it.

I still can't believe there aren't more binds in the valve gear, it must just clear.

[sizemore]

I didn't quarter the rear driver itself. Instead I matched it with the 3rd (traction tire) driver and that seemed to work. It was close before and run good by itself, but pulling a train load it didn't. As it is now I ran it with a train for 1/2 hour so I'm happy enough with it.

I still can't believe there aren't more binds in the valve gear, it must just clear.

Yeah that is what I am doing matching D3 and D4. I noticed D3 is not really touching the rails, when I ran the loco with no rods to check where the hitch is, she would barely move under her own power. I will play more tonight to get the last little hitch at 11 out. Sometimes it goes a couple feet before hitching in Speed Step 1, other times it goes one revolution before hitching again. What really bugs me the most, anything metal is not primed so the white paint just flakes off. The time fixing this could really be put into the effort for the Skunkwerks Super-Berk v2.0.

The S.

[jdcolombo]

Could you guys describe in just a bit more detail (or perhaps post a photo) of just what you're doing with the 4th driver?  When you say "match D3 to D4" what does that mean? When Chris talks about twisting the drivers to do the quartering, does that men that you hold one of the D4 drivers and twist the other?  Or what?  Sorry - I'm having trouble coming up with the right mental image of what you are doing.

Although I've gotten two of my Berks to run pretty darn well by adjusting the CV's on the Tsunami's BEMF circuit, it would be better if they ran great to begin with, and I noticed that one of my units had the dreaded "hitch" (the other just seemed to run a bit haltingly at low speed - not really a hitch per se as a sort of surging/stopping).  So I'm game to try some adjusting myself.

Thanks!

John C.

[sizemore]

For myself, I'm just pulling the 4th driver out of the mechanism and adjusting the quartering a hair rotating the wheels with light pressure, reassembling and testing. If the quartering is out of alignment the rods will cause D3 and D4 to bind resulting in a hitch. If you watch the operation, while looking down the track you can see the rod between D3 and D4 is not in alignment with the rod from D1-D3. It looks like a "rubber" pencil as it rotates, it will almost look like the D4 rod is "chasing". If there is droop from D3-D4 in the rod, then you have to open the quartering a smidge.

Hope this helps,
The S.

[Chris333]

I never took the rods off or the driver out    Just held one side of D4 with fingers and spun the other side. And by matching it with D3. I mean if one side lines up perfect with D3 I flip it over and see that side does not match. So while I did not try to quarter it 90 degrees exactly as a separate driver. I did make it match D3 and that made all the drivers closer to the same.

If yours still didn't run great with the main rods removed then I doubt you have a quartering problem.

[sizemore]

I never took the rods off or the driver out 

I hate your luck!


The S.