Bachmann Thomas and Friends Special HO Train Set Problem [SOLVED]

[absterok]

hi

i got a Bachmann Trains Deluxe Thomas and Friends Special Ready-to-Run HO Train Set for my son from the US, im in the UK.

I purchased a Hornby PSU which fitted just fine, its 15V DV i believe

problem is the controller only works in one direction, its a blue controller with a direction switch, but it only seems to work when switched to one side only

i got another replacement off amazon and it does the same thing, have i been unlucky twice or is it something else

ive taken the train to my fathers hornby track and the train goes both directions no bother, a multimeter across the track only shows voltage when switch in the working side.

any clues?

thanks
scott

[jward]

you didn't mention whether the controller was putting out voltage in both directions. measure your voltage at the terminals of the power pack, then at the ends of the wires going to the track. if you have voltage in both directions both places, you have a bad section of terminal track. if you get good readings at the controller but not at the end of the wires, the wires are bad. if you get a bad reading at the controller, replace it.

[absterok]

the controller has a 3.5mm stereojack type connector at one side, its difficult to test at output, but at end of cable that plugs into track i only get a voltage when the switch is left, nothing when at right position

this is the controller  http://compare.ebay.com/like/160580124639

at the track, its a plug in connector, there are 2 spade connectors on the track, it i pull out the plug and reverse it the train goes in the opposite direction, i think this means the track and connectors from the track onwards is fine.

are the controllers ac or dc, could it be some incompatability with the hornby psu, unfortunately the bachmann psu states 110v so it will blow for sure if i plug it in.

thanks
scott

[Jerrys HO]

absterok,
when you checked voltage and you switched to the other direction did it drop to zero or did it show a negative in voltage? I just checked mine and with the multi-meter hooked up when I switched direction it showed negative voltage of the same positive voltage. This is showing the track feed cable is fine. If yours drops to zero than I would assume your controller is faulty.
The two center posts are for AC power for switches, lighting etc.
  As for being compatible with the Hornby I would not know but in a previous thread there was another poster that did have problems with the Hornby system on a different problem.
  Jim Banner  has helped alot of out of the states posters such as yourself I would suggest sending him a personal message for his input.
Jerry

[jward]

you've done a good job of troubleshooting this controller. i have one final question. since the two yellow terminals at the top of the controller are ac, do you read 16v ac between them? the way most controllers are set up, the opwer supply steps down the ac to about 16v. on most it's done internally but yours has a seperate power supply. the ac is sent through a rectifier to be converted todc, then regulated to 12v dc max, before going through the direction switch. it sounds to me like it is the direction switch that is faulty. if so, the ac part should work normally.

[absterok]

thanks for everyones help

has anyone got a bachmann psu that can test the output from it?

the bachmann psu states 16v AC

The Hornby says 15V DC

when i tested the yellow poles i did get a voltage and it was unaffected by the dial, but i wasnt looking too much at what it was (i could do with a digital meter), but im wondering if on the bachmann controller the 16V AC terminals are a sort of passthrough

im at work now, but i'll test it and note whats coming out of where, i dont really understand AC/DC, maybe im just unlucky with 2 faulty controllers.
thanks
scott

[absterok]

absterok,
when you checked voltage and you switched to the other direction did it drop to zero or did it show a negative in voltage? I just checked mine and with the multi-meter hooked up when I switched direction it showed negative voltage of the same positive voltage. This is showing the track feed cable is fine. If yours drops to zero than I would assume your controller is faulty.
The two center posts are for AC power for switches, lighting etc.
  As for being compatible with the Hornby I would not know but in a previous thread there was another poster that did have problems with the Hornby system on a different problem.
  Jim Banner  has helped alot of out of the states posters such as yourself I would suggest sending him a personal message for his input.
Jerry

it seemed to dip to negative then return to zero almost immediately, i hadnt seen your post at this point, i was unsure about this, i will look at it again tonight and take notes, i have a digital meter now which might help a bit, thanks scott

[jward]

the bachmann psu states 16v AC

The Hornby says 15V DC

when i tested the yellow poles i did get a voltage and it was unaffected by the dial, but i wasnt looking too much at what it was (i could do with a digital meter), but im wondering if on the bachmann controller the 16V AC terminals are a sort of passthrough

im at work now, but i'll test it and note whats coming out of where, i dont really understand AC/DC, maybe im just unlucky with 2 faulty controllers.
thanks
scott

i think that's your problem. you are using a dc power supply when you should have been using ac. the bachmann unit is trying to convert dc to dc.

ac is alternating current. the simple explanation is that the voltage varies between about +22v and -22v. averaged together, the wave form equals 16v for each half otf the cycle, + and -

the ac switches between positive and negative at a very high rate, in the us it's 60 times a second. that is called the frequency, and measured in hertz.

dc is direct current. it's like a battery. the polarity is constant. on properly filtered dc the voltage is constant too.

a rectifier uses devices called diodes, which are like a one way street for electricity. it will let the positive half of the ac pass and block the negative. using the network of diodes in a rectifier, you can convert both the positive and negative halves of the ac to positive dc at twice the frequency of the ac. filtering and voltage regulation circuits smooth this rippled dc out to a near constant dc voltage.

the regulated dc is then run through a reversing switch to allow you to change polarity (thus direction of the locomotive) then through a variable resistor called a rheostat, which controls locomotive speed.

your ac terminals on the controller should equal the input ac voltage. in this case since you are using the hornby power supply it should equal 15v dc. try to find another power supply rated at 16v ac and at least 1 amp output. hopefully this will clear up the problem.

ac and dc are not the same......

[Jim Banner]

I mostly agree with what Jeffery said but for the effect you are noticing, I suspect there is one small difference.  Rather than a regular reversing switch which inverts the polarity, I believe the Bachmann controller rectifies positive half cycles for one direction and negative half cycles for the other direction.  Thus a power supply putting out dc would supply positive voltage for the one direction but would not supply any negative voltage for the other direction.  One solution that would allow you to use what you already have is an external reversing switch, basically a cross-wired toggle switch.  This is the method of reversing Jeffery talked about.  This would connect it between the output of the Bachmann controller and the track.  Here is a wiring diagram.  The colours have no particular meaning - they just distinguish between the wires.




Jim

[jward]

to add to jim's suggestion about the external reversing switch, atlas makes a product called the twin, which is two  slide switched each internally wired the same as jim's diagram, in one housing.
http://www.trainsetsonly.com/page/TSO/PROD/150-210

you'd wire the red and  black wires (see jim's diagram) to the side two terminals, and the blue and green ones to one pair of top terminals. you can screw the twin to your baseboard with two wood screws included with the twin. there is also a center off position on the slide switch which kills power to the tracks.

another use for these is to operate tortoise switch motors, or any other dc motor driven item such as a turntable.

[absterok]

thank you to everyone to helped with this issue.

This was indeed a DC power supply problem.

I finally tracked down a AC/AC 16V PSU for use in the UK and it is now working as it should, both directions and train going faster than ever, Jack my son is now very happy!

http://www.stagebeat.co.uk/product.php?product_id=121310
Peavey Power Supply Unit PSU 16v 1100mA AC
£20.00

many thanks
Scott

[Jim Banner]

Scott,

Thank you very much for taking the time to post a solution that works.  Facts like these are worth their weight in gold, especially to others who run into the same problem.

Jim