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Lionel BW-80 Transformer

raising4daughtersraising4daughtersOGR Forum Member SUPPORTING MEMBER

I posted multi-part question on transformers and appreciate all the responses.  I think I've got everything in order.  But, there was one question I didn't get answered, and it's regarding my BW-80 transformer that came with my Santa Fe FT set from about 10 years ago.  It's the one where the throttle looks like the CW-80 but has a separate power-pack.  It's only putting out about 14V but I recall it putting out 20 or more when it was new.  My LHS wasn't interested in repairing it, stating that it's too expensive to fix the newer transformers due to the electronics. 

 

Does anyone think it would be worth fixing? Since it's 2 pieces, it takes up a lot real estate on a layout.  Would the throttle work with another 135W or 180W power pack (or "brick") that Lionel sells?  If so, I'm thinking that might be a better way to go.

 

Thanks!

 

Scott

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ADCX RobADCX RobOGR Forum Member SUPPORTING MEMBERDIGITAL SUBSCRIBER

Because you mention you are isolating the transformer from the track it sounds like you are measuring at the red & black posts...  how about measuring just the part you plug into the wall, without the controller?

 

That should be 17.9-18 volts.   The voltage coming out of the controller at the red & black posts will only read about 14 volts depending on which meter you use, even if it's working properly.

raising4daughtersraising4daughtersOGR Forum Member SUPPORTING MEMBER
Originally Posted by ADCX Rob:

Because you mention you are isolating the transformer from the track it sounds like you are measuring at the red & black posts...  how about measuring just the part you plug into the wall, without the controller?

 

That should be 17.9-18 volts.   The voltage coming out of the controller at the red & black posts will only read about 14 volts depending on which meter you use, even if it's working properly.

Rob - Thanks for your help and advice.  I did what you said, and you're right, I'm getting 18+ volts out of the plug from the brick before plugging it into the controller.  Out of the controller, however, I'm only getting 14V as measured at the black and red posts and on the tracks. 

This surprises me because the throttle's numbering goes up to 22 as if to imply 22V maximum. 

 

In some respects, if 14V is the max, that has some appeal to me on the Christmas layout because the kids like to open the ZW's throttles full which puts out 19.5V on the tracks and has the trains screaming around the tracks.  But, I'm thinking the BW won't work with my permanent layout (in process) in the basement since I'm hooking up TMCC.

Last edited by raising4daughters
C challenger3980OGR Forum Member

I don't know if the BW controller uses phase control (often called chopping) to vary the voltage, in the same way as the CW-80, if so most common voltage/mutimeters will not give an accurate voltage reading. To get an accurate voltage reading from a phase control controller, you will need a TRUE RMS voltage meter. The "Brick" is probably putting out a pure sine wave current, which a common meter will read accurately, but the BW CONTROLLER is using phase control to adjust the voltage, which is confusing your meter, and causing the differences in output readings between the brick and the controller.

 

Doug

ADCX RobADCX RobOGR Forum Member SUPPORTING MEMBERDIGITAL SUBSCRIBER
Originally Posted by raising4daughters:

...however, I'm only getting 14V as measured at the black and red posts and on the tracks...

Yes, but how do the trains run? 
 
As Doug & I have mentioned, so far, you have no problem - this is a normal reading for full output on these transformers when checked with an ordinary household VOM.  To see the full 18 volts, you will need to use a $200 meter or an oscilloscope.

 

C challenger3980OGR Forum Member

Hi Rob, IIRC, You are familiar with Bob Nelson (Lionelsoni) on another forum, Bob had mapped out the various TRUE values for the indicated  values when measuring the voltages from chopped wave transformers with common meters, seems that the readings were fairly predictable/consistent with most meter/transformer combinations. Did You happen to save a copy of Bob's chart, by any chance? I wish that I had.

 

Doug

ADCX RobADCX RobOGR Forum Member SUPPORTING MEMBERDIGITAL SUBSCRIBER
Originally Posted by challenger3980:

Did You happen to save a copy of Bob's chart, by any chance? I wish that I had.

 

 

Doug

 

Originally Posted by lionelsoni:

Do you have a "true RMS" voltmeter?  Most AC voltmeters assume that you are measuring a sinusoidal waveform, which the CW-80 definitely does not put out.  Here is a correction chart for use with an ordinary voltmeter:

 

Meter          RMS 
  0          0
  0.5          1.6
  1          2.7
  1.5          3.7
  2          4.6
  2.5          5.4
  3          6.1
  3.5          6.9
  4          7.5
  4.5          8.2
  5          8.8
  5.5          9.5
  6          10
  6.5          10.6
  7          11.2
  7.5          11.7
  8          12.2
  8.5          12.7
  9          13.2
  9.5          13.7
 10          14.1
 10.5          14.6
 11          15
 11.5          15.4
 12          15.8
 12.5          16.2
 13          16.6
 13.5          16.9
 14          17.3
 14.5          17.6
 15          17.9
 15.5          18.2
 16          18.5
 16.5          18.8
 17          19
 17.5          19.3
 18          19.5
 18.5          19.7
 19          19.8
 19.5          19.9
 20          20

 

You can see that when the CW-80 is putting out its full 18 volts, an ordinary meter (which I'm assuming is what you've got) should read about 15 volts, which is not too far from what you're seeing on the accessory output.  The simplest explanation for the track voltage's being so low (actually about 14 volts RMS) is that the handle is attached to its shaft at the wrong angle.  I don't have one here; but maybe you can see a way to get the handle off and reattached at a different angle.

Last edited by ADCX Rob
raising4daughtersraising4daughtersOGR Forum Member SUPPORTING MEMBER

The trains run as well on the BW at 14.5V as with the ZW reading 18.9.  I'm guessing the BW is putting out a chopped sine wave which you've explained to be confusing to my ordinary voltmeter.  I had watch a Mike Reagan video explaining the difference, but didn't put 2 and 2 together.  I had never actually measured the track voltage with the BW on my prior layout; if I had, I bet it was 14.5V then, too.  As I see it right now, I probably don't have a problem....thanks for the explanation.  Scott

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