Bachmann DMU - Pickup problems

[drewn]

Hi guys,  

 

As an owner of many Bachmann locos I am becoming more and more disappointed with certain aspects of their performance.

  

I have a new class 101 DMU which tends to stutter badly over points, etc.  Having checked continuity with a meter I find that there is next to none between the two bogies on the power car.  One problem seems to be the rubbing contacts between the brass pickups and the PCB  ( I see that in previous posts this was overcome by inserting a small spacer which increases pressure between the two, or by soldering wires between the pickup and the pcb)

 

Also, the continuity between the brass pickups and the axle bushes is extremely poor. - Not sure how to overcome this!!

 

All things considered, I find the whole pickup design poor and find it strange that something more robust has not been designed by Bachmann.  

 

By the way, there is no continuity between the powercar and the trailing car.   Haven't opened the trailing car up yet but I'm assuming its wheels should be electrically connected to the power car.

 

Any suggestions guys

 

Drew

[34theletterbetweenB&D]

There's no electrical connection between cars on the very similar 105, 108 and lightweight DMU sets that I have seen.

 

Does new mean a very recent purchase that has had little running? If so, just give them an hour or two of running to polish up all the contact surfaces in the conduction paths.

 

I have soldered on thin wire connections to the pick ups (that's personal preference over rubbing connections for long term reliability).

 

The pick up from the pinpoints has given no trouble at all, and that applies to both the MU's and the Pullman cars which share the same arrangement. I haven't lubricated them either, since they are very free rolling as supplied. Check for accumulations of dirt or fibres.

[giz]

As far as I know the electrical connection between the two cars only powers the trailer lights allowing for only one dcc decoder in the power car. There are no pickups on the trailer.

[drewn]

There's no electrical connection between cars on the very similar 105, 108 and lightweight DMU sets that I have seen.

 

Does new mean a very recent purchase that has had little running? If so, just give them an hour or two of running to polish up all the contact surfaces in the conduction paths.

 

I have soldered on thin wire connections to the pick ups (that's personal preference over rubbing connections for long term reliability).

 

The pick up from the pinpoints has given no trouble at all, and that applies to both the MU's and the Pullman cars which share the same arrangement. I haven't lubricated them either, since they are very free rolling as supplied. Check for accumulations of dirt or fibres.

 

The loco is recently purchased and has NOT run too much , so you may be right about the "polishing up"  aspect. 

 

I might just leave it for a while and see if it improves

 

Thanks

 

Drew

[drewn]

As far as I know the electrical connection between the two cars only powers the trailer lights allowing for only one dcc decoder in the power car. There are no pickups on the trailer.gGiiz,

giz,

 

Sorry but there ARE pickups on all 4 axles on the trailer. The trailer lights, I assume, are fed via the tow bar wiring

 

Drew

[Dunsignalling]

There's no electrical connection between cars on the very similar 105, 108 and lightweight DMU sets that I have seen.

 

Does new mean a very recent purchase that has had little running? If so, just give them an hour or two of running to polish up all the contact surfaces in the conduction paths.

 

I have soldered on thin wire connections to the pick ups (that's personal preference over rubbing connections for long term reliability).

 

The pick up from the pinpoints has given no trouble at all, and that applies to both the MU's and the Pullman cars which share the same arrangement. I haven't lubricated them either, since they are very free rolling as supplied. Check for accumulations of dirt or fibres.

The 101 does have a conductive coupling bar between cars.

 

Usefully, the part in question is available separately and is just the right length to give proper close coupling on the 4-CEP and Thumper models.

 

John

[giz]

giz,

 

Sorry but there ARE pickups on all 4 axles on the trailer. The trailer lights, I assume, are fed via the tow bar wiring

 

Drew

You're right, I hadn't noticed that before because the trailer lights don't work if not connected to the power car.

 

However, as the connector between the two cars only has two poles it doesn't appear to be able to feed power back to the motor.

[drewn]

You're right, I hadn't noticed that before because the trailer lights don't work if not connected to the power car.

 

However, as the connector between the two cars only has two poles it doesn't appear to be able to feed power back to the motor.

 

giz,

 

I agree with your last point. Unfortunately, it means that pickups are only effective on the power car, ideally on 4 axles, but with mine, two of them are intermittent which leads us back to the earlier point that some bedding-in, or polishing-up might be the solution!

 

Drew

[giz]

Looking at the circuit board on the trailer it looks like the lights may be supplied from the trailer pickups but switched by voltage from the drawbar connection.

 

You could possibly run a couple of wires from the trailer pickups through to the power car and connect them to the pickups there to help thing but that may have an effect on the trailer light switching.

 

I've not had any problems with any of mine, even a sound fitted one which would show up any deficiencies.

[cravensdmufan]

giz,

 

I agree with your last point. Unfortunately, it means that pickups are only effective on the power car, ideally on 4 axles, but with mine, two of them are intermittent which leads us back to the earlier point that some bedding-in, or polishing-up might be the solution!

 

Drew

Had the very same problem with my Bachmann 101's.  They were picking ip juice from the power bogie wheels but only intermittently from the trailing bogie.

 

See my solution here http://www.rmweb.co.uk/community/index.php?/topic/70508-Bachmann-dmu-pick-ups/?p=1947576 which has cured it.

[drewn]

Had the very same problem with my Bachmann 101's.  They were picking ip juice from the power bogie wheels but only intermittently from the trailing bogie.

 

See my solution here http://www.rmweb.co.uk/community/index.php?/topic/70508-Bachmann-dmu-pick-ups/?p=1947576 which has cured it.

 

cravensdmufan,

 

Thanks , I read your piece and looks to be exactly what I need.. The main problem I've got is when the dmu crosses the diamond crossing. I had shorting issues in the past, and ended up coating much of the crossings with nail varnish.

 

This cures the shorting but I need to have two bogies effectively picking up power.

 

So, while I don't necessarily need the trailer car to pick up power  ( it would be nice if it did) I definitely need the power car bogies to perform better.

 

Thanks 

 

Drew

[34theletterbetweenB&D]

The 101 does have a conductive coupling bar between cars.

 

Usefully, the part in question is available separately and is just the right length to give proper close coupling on the 4-CEP and Thumper models

You're right, I hadn't noticed that before because the trailer lights don't work if not connected to the power car.

 

However, as the connector between the two cars only has two poles it doesn't appear to be able to feed power back to the motor.

 

So there's useful information that has surfaced, the 101 has slightly different electrical arrangements to Bach's earlier releases of BR first gen DMU models.

 

I have fiddled around with my 105 pairs to have through wiring for all wheels picking up, and all lights control from 1 decoder. While I would have liked it had Bachmann provided such a solution, at the near giveaway price of £70 of happy memory, I'll forgive them this slight lack of sophistication...