Bachmann Thomas Decoder Problems

[adamski]

Was wondering if anybody could shed some light on a problem I have. My layout is dcc using massoth dimax 1210z equipment and navigator. All my LGB and Piko trains are fitted with massoth decoders and run fine but the Thomas range for my kids seems to have problems. I have fitted james and percy with again massoth decoders all run fine. Thomas and Emily are fitted with the Bachmann LS soundtraxx decoders and they seem to play up. What we find is they will move of fine then if they come across a slightly dirty bit of track stop then stutter a bit then stop then wont move any more until you stop the train on the navigator and then reapply the throttle. Its just so odd as percy will go over the same track no problems at all. They have done this from new straight out the box. Any thoughts as don't want to loose the sounds as my little boy loves the trains but he gets upset because Thomas just keeps stopping and starting. I was thinking of sticking a second decoder in ie massoth to just run the motor and leave the soundtraxx card for the sounds just seems a waste of money. So does anyone have any views on the soundtraxx cards and if they have had the same problems would be great to here any ideas to fix this

Many thanks

Adam

 

[Sean.]

The Thomas..is this the newest .. there were some older ones from Lionel that needed the brushes changed out..
I just re-read the title ..never mind

 

[PhilP]

Sounds very much like dirty tyres, and possibly dodgy pickups, to me..

Clean the tyres/wheels (not with anything abrasive!

Go down each side of the loco with a meter and check all pickups and wheels are connecting.


If all else fails, then fit a power-buffer in the loco.

 

[Greg Elmassian]

Nope, it is that decoder, mine acts exactly the same. It's a cut-down version of the Tsunami.

I have exactly the same issue, and I would recommend finding a way to put a keep-alive cap on the board. It's one of my projects to do so.

I mention this problem on my web site.

Bachmann / Soundtraxx "Thomas family" OEM decoder

Very poor situation... but my experiences with SoundTraxx large scale decoders has been poor almost every time I have used them. Sensitivity to overvoltage, the "crippling" of features, and this issue. There's no excuse in modern days for a decoder that acts like DCC was 20 years ago.

Greg

 

[adamski]

Thanks for your replies, Greg what you say on your site is spot on. That's what happens to mine every time its a real pain. Don't suppose you have figured out where you could install a power buffer yet ? really need a schematic for that board before I could try and figure it out myself . I was wondering if you could some how copy the sounds or if any one had the sounds so you could install them on a massoth sound decoder wish I had asked this question sooner as I purchased another soundtraxx card for toby. I have a two year old who just cant get enough trains Thomas mainly but my hope is to keep him with a hobby rather than a tablet or phone in front of his face. Any suggestion on a way to resolve this would be greatly apricated

Many thanks

Adam

 

[Greg Elmassian]

I updated my page, refresh it (you might have to do the forced refresh on your browser).

I've annotated it and there's 3 decoder pictures there, the top and bottom of the Bachmann OEM decoder you and I have, and the 3rd picture is of a Soundtraxx Tsunami 4400... notice they are basically the same, but the Bachmann version is stripped down, and does not have the "current keeper" connector... I'll figure this out and put on a cap bank. That should fix the issue.

(no wonder they sell a keepalive unit, they need it)

Greg

 

[Deleted member 4232]

Moved

 

[Greg Elmassian]

I figured I would get my hands on the TSU-4400 and see what the "currentkeeper" connector is hooked to, it might be as you indicate above, just at the output of the full wave bridge from the rails.

It's too bad that they removed that connector from the "trimmed down" Bachmann OEM version, since they could have sold the currentkeeper board to more users (and with the limited pickup in the Thomas line, even more needed.)

Greg

 

[adamski]

Hi John Thanks for this information very helpful indeed but can I confirm before I go wiring the power buffer to the pcb that I am understanding what your saying correctly

The black negative wire from the power buffer to be soldered to The GND solder pad on the Thomas board as per your black arrow on your photo and the red positive wire from the power buffer to either of the diodes pads where you have marked with red arrows. The power buffer I am using is not a massoth one so I will install a switch to allow for programing the decoder in the future. On the massoth and lgb decoders you have to alter the cv to NOT allow analogue operation does the soundtraxx card need the same CV altering if it has that ability.

Many thanks

Adam

 

[Deleted member 4232]

Moved

 

[adamski]

Hi John

Thanks for the info, I have built my own power buffers in the past and have 8 running very happily in other short wheel base locos, I found this many years ago
Peckforton Light Railway: Massoth Power Buffer
and have built them to a slightly larger spec by adding a couple of extra caps. I will try and trace the copper track from that pad, I know if you hold the board up to a very bright light you can some times see the tracks through the boards coatings depending on how many layers the board is, I will also try and trace it using a multimeter.

Cheers

Adam

 

[Deleted member 4232]

Moved

 

[Greg Elmassian]

John, I know the SoundTraxx site has lots of info, but when it comes to the CurrentKeeper connection:

1. From the decoder end, you are supposed to plug the currentkeeper into the socket (which is NOT on this decoder)
2. There is no information what is inside the currentkeeper, but from reading the reference manual, since it takes some time to charge up, it must have an inrush-limiting resistor and probably a diode, the typical configuration
3. likewise there is no indication if it has a zener or other device to limit overvoltage, I would guess not as per your warning. The "reference" manual does not describe this.
4. the few connection diagrams it shows, shows it connected as you have indicated, to the output of the FW bridge from the track inputs
5. nowhere on their site could I find the max voltage rating.

Regards, Greg

 

[adverse camber]

I don't think it is just the soundtraxx decoder that is inhibiting Thomas. I fitted Massoth decoders to both Thomas and Percy some years ago. Percy is quite reliable but Thomas is not. Doesn't run too badly if the track is spotless but otherwise not a good runner. I think the pick up on Thomas is poor but am not sure why it is so bad (he has a high center of gravity and is light which cant help). I can see a capacitor might well help get over the rough spots.

 

[Greg Elmassian]

This is a very specific issue... when power is interrupted, the decoder does not resume, but you have to command the DCC speed to zero and then you can start up again.

"What we find is they will move of fine then if they come across a slightly dirty bit of track stop then stutter a bit then stop then wont move any more until you stop the train on the navigator and then reapply the throttle. "

Most decoders resume, or any change in speed starts them again.

Unique problem to this decoder.

Greg

 

[adamski]

Hi All

Thanks for all your help on this matter sadly adding the power buffer has not worked as I hoped or as we thought it might . The point on which I have soldered the power buffer on to the pcb is not keeping the decoder alive . I have tested this point as marked in post 7 and I am getting 22v dc as expected. As I had built my own power buffer I thought maybe it was a problem with it so I thought I would solder on a massoth micro power buffer to see if that would help but again it does not keep the decoder alive once the loco hits a dead spot or you remove the train from the track. To check all my work I removed the soundtraxx decoder and installed a massoth decoder sure enough lifted the train of the track wheels kept running for a good 20 secs. So it must be the point on which the buffer is soldered on to the decoder. I wonder if the main chip gets its power from some point before the bridge rectifier, stabbing in the dark here does anyone else have any thoughts. If that is the case anyway of building a power buffer before the decoder but not sure how we could do that. Guess we need to know where on the soundtraxx decoder we need to feed the power buffer in to keep it alive

Many thanks

Adam

 

[Greg Elmassian]

Pretty darn sure that the whole decoder is powered at the output of the bridge... silly question, but any chance the buffer was in backwards? Something does not make sense here... I'm going to make the mod myself, but it's a bit down on my priority list...

When I do complete the mod, I will post it on my site.

Greg

 

[adamski]

Please feel free to correct me if I have got the wiring wrong

So I have a soundtraxx Thomas sound card which I have taken the positive dc feed from the bottom diode in post7 marked with a red arrow and connected that to the red wire from the massoth emotion powercap micro. I have then taken a black wire from the ground marked GND on the board as per post 7 with black arrow. I have run this to the switch and joined the black wire from the emotion powercap micro together and soldered them both to the switch. I have then taken the white wire from the powercap micro and soldered it to the output side of the switch I have checked the switch with a multi meter so that all ok. I have bleep tested that when the switch is in on position I get continuity from gnd of pcb through to wire that feeds powercap micro and when switch is off no continuity. I have also measured voltage to the powercap micro and am getting 22v dc across the black and red wires so voltage is going to the powercap micro but its not keeping the decoder running after I remove the train from the track. Just wondering would any cv on the soundtraxx card need to be altered set to a certain value to allow it to work ? Is this all correct as taken the wiring from post 7 and from massoth powercap micro instructions. page 7 illustration 4+5

 

[Greg Elmassian]

The powercap micro has a "charge" input I believe, and you have hooked that charge input wire the negative side... not sure that is what makes it "charge'.

I have seen the 3 terminal keepalive units, and they range from just some caps, to caps and a diode to caps, a diode and resistor, and to having a circuit board with a "charge" wire.

I'd like to see the documentation on how this 3rd wire works... do you have any documentation on this?

(normally I would think the charge control wire would get positive to charge, not negative)


Update, I found the manual and I see the switch, but what is not clear, is it "off" when the circuit is broken (switch off) or connected?

Did you test with the switch in both positions, i.e. leave the switch in one position.... put on the rails, let it charge and take off.... then do the experiment with switch in other position?

see if the lights stay on first.... perhaps the motor will always stop when no DCC commands come.... period.... so the lights should tell you if the buffer is working.

Greg

 

[adamski]

Hi Greg

I did try the switch in both positions and it made no difference. I have checked the powercap on a massoth decoder and it works fine. I added a light to the soundtraxx decoder today as you suggest and left the train on the track for 2 mins light was on as soon as I lifted the train of the track light went out. Tried it with switch in both positions made no difference. Also tried it by just having the whistle blowing same again lifted it of the track and it stopped. I have a Percy fitted with a massoth decoder and I don't have any of these problems. I feel like writing to them and showing them how badly their decoders work as it is a very poor product and I don't feel its fit for purpose because unless your track is like brand new it stutterers and just keeps stopping and just does not run. Just a shame this is aimed for children and it causes so much stress to get the thing to run. The whole having to bring throttle to zero before it will work again is a real joke and its not a cheap decoder at £100 for a pcb which does not even come with any wires soldered on it or a speaker unlike other brands

Emailing some company's to see if they can program a massoth card with Thomas sounds so I can take the soundtraxx decoders out and post them back to them.