Tortoise Point Motors Latent Fault with Wipers

[brossard]

I just viewed the attached video:

 

 

Food for thought.  I am now strongly considering having a look at mine (I only have a handful thank goodness) and proactively repairing.

 

The group did test Cobalts but found the current draw was too high for their Digitrax stationary decoders.

 

I'm amazed this hasn't come up before now - yes I did do a search but found nothing.

 

Anyway, I'll stop wittering and let you get on with watching.

 

John

[Stephen Freeman]

I am sure problems with wiper contact system have come up before in the past but it was some time ago and I think it  was down to wear on the circuit board rather than the wipers. I too have been impressed by the MTB ones, but these days prefer to use servos, cheaper alternative and easily replaced if needed. Any additional switching can be achieved with microswitches.

 

If you use the Exactoscale Tortoise Adapter plates, it is useful to know that Cobalts can be used with the self-adhesive pads provided rather than trying to use screws/bolts, which won't line up.

[Sitham Yard]

6 hours ago, brossard said:

I just viewed the attached video:

 

 

Food for thought.  I am now strongly considering having a look at mine (I only have a handful thank goodness) and proactively repairing.

 

The group did test Cobalts but found the current draw was too high for their Digitrax stationary decoders.

 

I'm amazed this hasn't come up before now - yes I did do a search but found nothing.

 

Anyway, I'll stop wittering and let you get on with watching.

 

John

I have referred this to the electronics expert in our O gauge group. It would seem that the problems are likely to be heat related due to soldering directly on to the connectors and/or using the switches to switch, rather than to carry, a higher current than they are designed for. We only use separate connectors (expensive and can be hard to obtain) and use relays to switch the DC traction supply and have not had this problem. The only issues we have had are with connectors coming loose or being too long and not lining up correctly. A small piece of plastic in each end of the connector can help with the latter.

Andrew  

[Stephen Freeman]

47 minutes ago, Sitham Yard said:

I have referred this to the electronics expert in our O gauge group. It would seem that the problems are likely to be heat related due to soldering directly on to the connectors and/or using the switches to switch, rather than to carry, a higher current than they are designed for. We only use separate connectors (expensive and can be hard to obtain) and use relays to switch the DC traction supply and have not had this problem. The only issues we have had are with connectors coming loose or being too long and not lining up correctly. A small piece of plastic in each end of the connector can help with the latter.

Andrew  

no end of trouble using the plug-on connectors and won't use them now.

[brossard]

1 hour ago, Sitham Yard said:

I have referred this to the electronics expert in our O gauge group. It would seem that the problems are likely to be heat related due to soldering directly on to the connectors and/or using the switches to switch, rather than to carry, a higher current than they are designed for. We only use separate connectors (expensive and can be hard to obtain) and use relays to switch the DC traction supply and have not had this problem. The only issues we have had are with connectors coming loose or being too long and not lining up correctly. A small piece of plastic in each end of the connector can help with the latter.

Andrew  

 

Now that's an interesting point.  When I was starting out with Tortoise, some 20 years ago, I soldered wires direct to the board.  At a show I experienced a short that was hard to diagnose and eventually found two frog polarity wires touching.  After that I went to edge connectors which require the shims.  My new 0 gauge layout has been running for a few years now with no Tortoise issues.  I have converted the edge connectors to those with screw terminals.  Circuitron do one, but mine is from someone else:

 

 

 

These are customized to the Tortoise board so no shimming.

 

John

[5BarVT]

On 04/10/2023 at 13:42, brossard said:

These are customized to the Tortoise board so no shimming.

I believe to the old tortoise board thickness.  Recent enforced retooling has moved to standard thickness PCB which will fit industry standard edge connectors.

Check before you fit!

Paul.

[roythebus1]

I've got a mixture of Tortoise, Fulgurex and some 1970s machines made by Old Pullman. I'v not had any problems with tortoise motors yet, the Old Pullmans are showing their age as they are a not a slow-acting machine as such, but an earlier version of the Fulgurex. Both those types give problems with the contacts getting dirty or corroded over the years and the worm gears wearing out.

 

I haven't yet bothered to try servo motors, they look quite complicated to me, i need something simple without electronics! I like relays and things  I can hit with hammers.

[brossard]

1 hour ago, 5BarVT said:

I believe to the old tortoise board thickness.  Recent enforced retooling has moved to standard thickness PCB which will fit industry standard edge connectors.

Check before you fit!

Paul.

 

The shimming is for width, not thickness.  So, 1mm x 1mm plastic strip is what is needed.

 

51 minutes ago, roythebus1 said:

I've got a mixture of Tortoise, Fulgurex and some 1970s machines made by Old Pullman. I'v not had any problems with tortoise motors yet, the Old Pullmans are showing their age as they are a not a slow-acting machine as such, but an earlier version of the Fulgurex. Both those types give problems with the contacts getting dirty or corroded over the years and the worm gears wearing out.

 

I haven't yet bothered to try servo motors, they look quite complicated to me, i need something simple without electronics! I like relays and things  I can hit with hammers.

 

I took apart two from my spares box today.  One of the wipers was loose, the others felt firm enough.  However the design is poor IMO with just one plastic "rivet" and a locating pin to hold the wipers on.

 

John

[Chris White]

On 04/10/2023 at 11:53, Sitham Yard said:

... It would seem that the problems are likely to be heat related due to soldering directly on to the connectors and/or using the switches to switch, rather than to carry, a higher current than they are designed for. ...

I would disagree with those suggestions as the wipers are becoming detached from the carrying arm. Their attachment points are a long way away from the connections where any soldering takes place. As to switching of current the switching of DCC power to the point frog would normally take place when there is no rolling stock at the frog and hence no DCC current flowing through the frog, the other contact is just switching a low current feedback signal.

[brossard]

28 minutes ago, Chris White said:

I would disagree with those suggestions as the wipers are becoming detached from the carrying arm. Their attachment points are a long way away from the connections where any soldering takes place. As to switching of current the switching of DCC power to the point frog would normally take place when there is no rolling stock at the frog and hence no DCC current flowing through the frog, the other contact is just switching a low current feedback signal.

 

I don't find it all that far fetched.  Anyone who has tried to hold a part in their fingers while soldering (yeah, I know, dumb idea) will attest to the rapidity of heat transfer.  General rule when soldering near plastic is always to get in and out with the iron as quick as you can.  Don't mess about.

 

That said, there is no need to solder wires to the board.  Best, IMO, to use a clip on attachment (see pics above) with screw terminals.

 

Shown here:

 

 

John

Edited October 7, 2023 by brossard

[brossard]

I did the bolt repair to two arms.

 

First the before:

 

 

Not great pics, my camera struggles with closeups.

 

Plastic pins, one on each wiper appears to have been melted to form sort of rivet.  As I was taking them apart, I noticed there seemed to be glue as well.

 

 

Bolt repair done.  The bolts on the right are 10BA (a bit too big I thought) and those on the left are 12BA, probably close to M1.2.  Nail polish applied to the nut side.  It is a proper fiddle to do and I'm not sure it's worth it.  I also notice that the wipers on the right are a bit squiffy so must test.

 

I just took apart a second pair of motors.  The wipers were on quite securely so this time I decided to apply some general purpose glue as a kind of belt and braces.

 

John

Edited October 7, 2023 by brossard

[brossard]

I spent today's work session removing point motors one at a time from the layout, disassembling and repairing as needed.  A couple of times one wiper simply fell out (yikes!) while at least one other came off with the slightest of finger pressure.  I did a combination of bolt and glue (for those wipers that seemed OK) repairs.  I marked the case with RG, RB or RGB (where one wiper was bolted and the other glued).

 

Wondering if this is a quality thing (Monday morning or Friday afternoon).

 

Anyway, if you have Tortoises it's worthwhile to have a look inside.

 

John