Caps on BLI SW7 motor leads - UPDATE

[tstage]

Greetings,

I'm removing the Paragon3 decoder in my BLI SW7 switcher and replacing it with a spare TCS LL8-LED decoder, which I had on hand.  There are caps connected to the + and - leads of the motor, as shown in the photo below:

The TCS decoder is temporarily wired in place and the locomotve programs and runs just fine.  Should these caps be removed, or can they just be left in place?  Lastly, what is the purpose of the caps on the motor leads?

Thanks,

Tom

[wvg_ca]

caps on the motor leads is to remove -possible- emi radiation, required by EU countries .... in general, they can be removed ..

[rrinker]

 Take them out. They are there for rf supression but unless you need to listen to an AM radio inches from your trains, you won;t have an interference issue. And they can interfere with the BEMF coming from the motor, so for best operation they should be removed. Easy enough to see if they are cuaing a problem, if the loco runs with the usual awesome low speed performance of a TCS decoder, they are fine to leave alone, if operation is a bit erractic and not up to the standards of other locos with TCS decoders - remove'em.

                                   --Randy

[tstage]

wvg_ca & Randy,

Thanks for the responses and explanations.

I figured there wouldn't be an issue about removing the caps from the motor leads.  The TCS website had a WOWSound install photo essay for a BLI SW7.  It showed the caps present in one photo then suddenly removed in the next but with no explanation given.  I only perused the photo essay so maybe I missed it.

As mentioned, the SW7 ran fine with the caps attached.  The only time I noticed any sort of erratic behavior, however, was when the SW7 slowed down.  It almost seemed to be fighting the momemtum.  Starting and picking up speed?  No problems.

I have a TCS KA1 wired to the LL8-LED decoder.  Would that also have added to any possible erratic behavior?  I have since removed the BLI-installed caps.

Tom

[gmpullman]

Hi,

Larry Puckett had a little blurb about chokes & caps recently:

Bachmann used them on their motor wiring possibly on every model. As Randy mentions, I remove them whenever I come across them.

Regards, Ed

[tstage]

I was able to successfully wire my spare TCS LL8-LED decoder into my BLI SW7.  It wasn't without it's challenges though:

• The LL8 is an 8-pin decoder.  I ended up soldering the wires to an 8-header then sliding that onto the 8 pins on the decoder board.  Should I decide to replace the decoder, all the wiring will stay intact.  The only thing that I'll need to unsolder from the decoder to remove it is the Keep Alive and an LED/resistor lead to F1
• I had to flip the wires to the three LEDs (two headlight, one interior) to make them illuminate.  Right rail went to Pin 8 and Left rail to Pin 4.  However, the LEDs would not light up.  I even double-checked the wiring between the 8-pin and LEDs to make sure that they were correctly going to the actual anode (+) and cathode (-) of each LED.  They were...but the LEDs still wouldn't illuminatee. 
• The interior cab LED is wired to F1 (plus 2K resistor) and independent of F0F & F0R - It's nice being able to turn it on or off and even adjust the dimness.

I'm pleased with the performance of the TCS LL8.  It characteristically operates the SW7 very smoothly and quietly.  There was even enough room to install a TCS KA1 Keep Alive up near where the speaker housing was located.

I ended up keeping the 8-ohm speaker in the event that I decide to add sound to the SW7 again.  If I do I would go with either Loksound or a TCS WowDiesel.   I'm perfectly content at the moment though with a quiet TCS motor-only decoder.

Tom

[tstage]

Boy!  Is the BLI SW7 geared low.   It barely cracks 20 sMPH at full throttle.  A yard goat it will be...

Tom