Poor running Bachmann - from bad to worse!

[cheekychops]

Hi,

 

I have a Bachmann 08 shunter that never ran well. I have just completed renumbering and weathering and reassembled to find that it ran very hesitantly – max setting on NCE cab.

 

This is what I have done and hopefully narrowed the issue down. BUT after my tender attentions it refuses to run at all.

 

1)      Disassembled and cleaned pickups and wheel insides, reassembled w light oiling on connector rods.

2)      Ran on rolling road with DC – OK at max setting (HM transformer) - 16V, still not brilliant. Ran for 20 minutes.

3)      Ran with chip (Hornby 8 pin) – still poor, hesitant running

4)      Reset chip - no difference

5)      Changed chip to Bachmann 8 pin – no difference.

6)      HERE I might have been stupid. But the small PCB and wired connections from pickups and to the motor looked frail. Cut, re-tinned and soldered back R, M+ and M- (see picture)

7)      Some joints on the front and back looked poor so I heated them up (15W iron), also the distance between soldered joints on the back looked, in places, too narrow so a little filing

 

Now it will not run DC or DCC.

 

Diagnostically (Picture below)

·         DC direct to motor - it runs!

·         DC 16V is reaching contact strips on chassis top V=16V

With plate in;

·         16 V from R (red wire) to M+ and M-

·         Short across M+ and M- (with meter)

·         No capacitance reading from cap straddling M+ and M-. Caps across motor (suppressors) measured OK

 

Any ideas? What does the cap straddling M+ and M- do? Can I remove it? Should or can I replace this PCB?

 

[Butler Henderson]

The cap is for interference suppression and not necessarily needed once a decoder if fitted, some routinely remove them  others only if the loco has a poor performance. Suggest dispending with the PCB and hard wiring a decoder.

[cheekychops]

Thanks, might give some more room too! I might remove the cap to see if that also works,,, will report back

[spamcan61]

I've never had one of those to bits, but shouldn't the black wire go to the top left pad on the circuit board, marked 'R'? 

Edited August 29, 2020 by spamcan61

[cravensdmufan]

Did you buy this loco new?

 

The reason I ask is that I purchased a used Bachmann 08 from a Toyfair  which ran OK at first but then started running erratically and slow / faster / slow.  Then sometimes stopped altogether. Then was OK again for a while after a "rest"!

 

Cleaned all pick ups and checked wires.  Then ran it on a rolling road with the body off and noticed a lot of sparking from inside the can motor.  I guessed it was the carbon brushes which can't be replaced.

 

Ordered a new motor from Bachmann spares at a very reasonable cost and loco is now perfect.

 

How the previous owner could have worn out a motor on an 08 is anyone's guess unless it was used as on a roundy roundy trainset!

 

 

 

[cheekychops]

No I did not buy it new. I'll look for the any sparking. It runs okay when direct current is applied though. In next few days will wire up the decoder directly.

 

I certainly don't have a roundy roundy set thus the need for smooth running.

 

Xhees

[DCB]

You get arcing on the commutator running without capacitors on DC, makes the brushes overheat, on things like X04s the brush heads will unsolder themselves. I always add ceramic capacitors, to DC locos so I wouldn't recommend removing ones fitted as standard.

[Theakerr]

I would suggest hardwiring the chip and the motor is the way to go.  I run DC, but on two occasions I had poor running and eliminating the PCB board was the answer.  I have done the same on a friends DCC fitted loco.  Based on the forum some PCB boards do appear to degenrate and it seems to apply to both Hornby and Bachmann.  Why is a bit of a mystery because there isn't much there to go wrong, but!  One of the more interesting situations I came across was on two  Bachmann  DMUs.  They ran sort of then one day one stopped running in the storage siding that is in a different room.  Got there and there was all kinds of smoke coming from it and I though for sure it was FUBAR.  Anyway took it to my work bench set it up and off it went, no problem at all.   So now I take apart the second one and you would not believe the amount of oil on the commuter shaft.  Depsite cleaning it when ran  on the bench at full voltage, lots of smoke and then nothing and excellent running.  That was at least six years ago and both are still running.  Posted my experience on the web after others had experienced problems and turns out i was not the only one to go through the smoke phase. 

Edited August 31, 2020 by Theakerr
Addition

[cheekychops]

Update:

 

I have hard wired the DCC chip to the motor but no improvement on rolling road or track.

 

I also removed the motor from the chassis and tried running it. It ran well! Even at low speed. Also there was a good deal of torque evidenced by pressing thumb onto worm gear. Reassembling - same poor running; the conclusion is the chassis although manual rotation does not appear stiff at any position. Any further ideas or is it off the the shop. I spent quite a bit of time renumbering and weathering it

 

Thanks for suggestions thus far.

[Theakerr]

When you removed the motor from the chassis and tested it, was the decoder still wired in?  I would love to get my hands on this because it sounds like a fascinating challenge.  Unfortunately I live in Canada. However if I had my hands on it my diagnostic route would be as follows

1)  with motor in the loco, remove all wires, connect DC to motor directly and try running the entire assembly on DC only.  If that doesn't work has to be a drive train issue,  I did have to 'rework with some fibre washer' a friends chassis in a L1 because the motor was not lining up with the gear train

2) if above works well, then find the leads from the wheel pick-ups as they come out of the chassis block and wire them directly to the motor.  If that works it is a DCC problem.  If it does not then it is a pick-up/wire problem.  Again on a friends A4 I found that one of the pick-up wires had broken at the bend as it went inside the frame.  The plastic covering appeared intact but on close observation you could see a tear.   I am not sure if the O8 is a direct wire from the pickups or if it is plunger/contact type.  Without taking one of my locos apart it is difficult to describe this system but it consists of wheel wipers on a sort of bent strip with the bent strip making contact with rivets in the chassis block or some variant of this, i.e. a two part pick-up system.   It is effective but can be a right pain to get correct after assembly and again.   On more than one loco the wire to the motor from the contact strip is riveted in but with only a few, like 2/4 thin wires actually making the contact.

3) Continue from there.

 

Do you have Facetime, if you do pm me?   I enjoy challenges like this.