K-27 chuff circuit transistor

[rslater]

Can anyone direct me to the posts on installing the switching transistor?  Now that I am ready to install my equipment,  I can't seem to find the posts.  What solder tabs, on the bachman board, does the emitter and base connect?   

[jimtyp]

Is this what you were looking for?

http://www.bachmanntrains.com/home-usa/board/index.php/topic,4021.0.html

Also check out:
http://www.trains.com/TRC/CS/forums/1323139/ShowPost.aspx

[rslater]

Hi Jimtyp,

You hit the nail on the head...exactly what I was looking for..now on to the installation...

Many thanks

Rick

[jimtyp]

Rick, are you installing a Phoenix 2K2 or P5?

Even after the transistor there is still a problem with these at higher speeds.  At about 40% of full throttle the chuff starts getting erratic and at about 60% of full throttle the chuff cuts out completely. 

The fix for the 2K2 is supposed to be simple (I only have a P5 so this is just what I've heard).  if you have the programming interface, you can go to the Terminals icon and uncheck the box next to the P1 Trigger.  This is supposed to be the fix.

For the P5 the fix is not as simple, and I still don't have a perfect fix. Phoenix is working on it but they don't have it yet.  It turns out noise is causing the chuff to fail at higher speeds.  They suggested I put a 0.1 capacitor on the transistor leads that go to J1:5 and J1:7.  This definitely helped but didn't fix it 100% for me.

[rslater]

Jimtyp

I am installing the P-5.  Keep me posted as to Phoenix's repair.  I may call them myself if I have the same problem.  I have the 2n2222 transistors but I also bought a larger transistor with higher wattage, it also has a heat sink.  I may try that one first.  Will let you know the results.

Rick

[Greg Elmassian]

There is virtually no current required, thus a larger transistor is not necessary or desirable.

Be careful when soldering, do not use excessive heat on the circuit board, especially in areas that have factory solder already.

Regards, Greg