Vitrains Class 37 full speed only

[508EMU]

Hi, not posted in a while, unsure if this is the best place to ask so mods feel free to move if required.

 

I've got a Vitrains 37 model (37401 in large logo), a while back it got knocked off a table. No physical damage to the body but ever since it doesn't run right.

 

It's DCC fitted. Since the drop it appears to have no speed control at all, so regardless what position you set the speed knob to on the controller it is always running at 100% speed. Aka no crawling around, its either as fast as it goes or nothing! It's the same in both directions, and I did change the decoder as I had a spare which made no difference.

 

I suppose something could have been damaged on the PCB inside the loco but I've not looked in detail.

 

Anybody have any suggestions where to start at all?

 

Thanks!

Edited July 10, 2023 by 508EMU
spelling error

[34theletterbetweenB&D]

Not encountered anything like that. Questions for clarification:

Are you using a DCC controller to operate it?

If yes, are other DCC fitted locos running normally on this DCC controller?

If no, have you tried switching off DC operation on the decoder?

[508EMU]

On 11/07/2023 at 11:52, 34theletterbetweenB&D said:

Not encountered anything like that. Questions for clarification:

Are you using a DCC controller to operate it?

If yes, are other DCC fitted locos running normally on this DCC controller?

If no, have you tried switching off DC operation on the decoder?

Hi, yes I am using a DCC controller and all other DCC fitted locos working fine with it.

I have not tried switching off DC operation on the decoder (didn't realise that was a thing!). I have got loco 0 DC operation disabled on the controller if thats any help.

 

The loco responds to commands via the controller when asked, and functions such as lights etc all work fine, the only issue with it is even if you set it to snail speed its full steam ahead!

 

Cheers

[mezzoman253]

I can't see how dropping a loco would alter the CV's in the chip. It's more likely to be something touching where it shouldn't. It could be the decoder/decoder socket interface having been misaligned due to the drop. However turning DC off when running a DCC loco' is prudent, as all manner of strange things can, and do, happen.

 

[LMSfan72]

It’s a very simple pcb so can you remove the decoder and take a picture of the top and post it? Might be possible to see something. If you can remove the screws and lift the pcb to get an underneath picture too, even better!

[508EMU]

Apologies for the delay in replying, this happened a while ago so the loco has been boxed up and dumped in the deepest darkest depths of the cupboard under the stairs and it's taken me a while to find time to dig it out.

 

Some photos attached of the PCB, I can't see any obvious signs of damage, but maybe I'm missing something.

 

I can't help wondering if the drop has damaged some gearing or something? I'm used to the older Hornby/lima motors and their many gears. Not too sure how these ones work.

 

 

Edited July 25, 2023 by 508EMU

[34theletterbetweenB&D]

On 25/07/2023 at 09:24, 508EMU said:

Some photos attached of the PCB, I can't see any obvious signs of damage, but maybe I'm missing something.

I cannot see anything of concern there, it's a simple layout to follow the tracks, and the pick up and motor wire connections appear to be in the right place, and there's no evident damage to the board.

 

Can you try the mechanism (with a blanking plug inserted obviously) on DC to see how it performs. If it runs normally on DC, then it's the decoder to check out...

 

On 25/07/2023 at 09:24, 508EMU said:

I can't help wondering if the drop has damaged some gearing or something? I'm used to the older Hornby/lima motors and their many gears. Not too sure how these ones work.

This is a side note: the mechanism layout is a central motor with shaft drives to worm gears, which each engage on a gear train tower on each bogie. Quite simply, the characteristic mechanical malfunction in the event of derangement of the shafts or gears is 'no go' or hesitant progress, rather than rapid progress; so I suggest nothing to worry about there.

 

 

[LMSfan72]

I do think that the diode(?) component just above the 8-pin socket looks to have a chunk out the side of it. I’ll have to think about that to determine if it might cause an issue of running but it would certainly affect something 

[508EMU]

12 hours ago, 34theletterbetweenB&D said:

I cannot see anything of concern there, it's a simple layout to follow the tracks, and the pick up and motor wire connections appear to be in the right place, and there's no evident damage to the board.

 

Can you try the mechanism (with a blanking plug inserted obviously) on DC to see how it performs. If it runs normally on DC, then it's the decoder to check out...

 

 

I can confirm it is the same on DC mode, as a side note the decoder that was in it is now in use in another loco and working fine. You are right in saying all wiring is in place and I have checked all are securely soldered to the correct place.

 

12 hours ago, LMSfan72 said:

I do think that the diode(?) component just above the 8-pin socket looks to have a chunk out the side of it. I’ll have to think about that to determine if it might cause an issue of running but it would certainly affect something 

Good spot, a closer look confirms it is indeed missing a chunk. May well have the answer! I'll focus on that and report back as and when I have an update.

 

Cheers all!

[LMSfan72]

Having thought about the damaged component I am trying to work out a path by which it would affect the motor! Perhaps the best way to test DC mode is to make your own jumper/blank to bridge the motor and track connections only - so there is nothing linking the lighting circuit. The damaged component is part of the rectification circuit for the lighting, so, bypass that completely and it should tell you if it is part of the problem. Most blanking plugs link the track to the white and yellow pins to feed the rectification. I would just cut the links in the blank to those pins, remove those pins completely or make some "staples" to simple bridge each track and motor pair...