KW - bad internal breaker?

I had a similar issue with my kw . The breaker would pop after a short while running a and b with less than 10 amps. Replaced breaker with 10 amp automotive type and no problems since. I do not leave layout on unattended and have a fire extinguisher since all my stuff is so old just to be extra safe.

Check that the terminal posts are not loose. I have a KW and have replaced a couple. The back side of the post is pressed in place and can work loose over time. It's an easy repair with a 8x32 screw and some nuts and washers.
I good rebuild would not be money wasted either. A new breaker and whistle relay would solve most problems and give added protection to modern electronics.

@Jeff_the_Coaster_Guy posted:

Direct shorting A and B to common popped the internal breaker and the red light turned on after about 2 seconds max. Seemed good.

Breaker is bad. The specification is 15-45 seconds for this test.

EDIT: This is with a .2ohm load. Lionel testers use two .1ohm resistors in series for this test.

Thanks for the advice guys.

Rob, I'm not doubting you, but I've seen some answers all over the place on this regarding KW breakers.  For example:

I'm guessing a screwdriver is less than 0.2 ohms across the distance between terminals.

This guys says within 10 seconds, presumably using "wire" that probably also has less than 0.2 ohms (24 ga coper wire is about 0.02 ohms per foot according to internet, so guessing that would pop the breaker faster?)

Similar to above, but within 5 seconds.  I guess with all the advice about checking the breaker, it's good advice if it also takes into account the actual resistance of the part being used to "short" the terminals.  Too much variability with thermal breakers and "methods" of shorting I guess?

I'll go and try to find a 0.2 ohm resistor.  I don't want to replace the breaker if there's indeed something wrong somewhere else in the wiring, but my amp draw measurements suggest that's not the case.

I also bought separate 6amp breakers to put on each side of my power loops right at the distribution relays.  Those should help too, but only if the internal breaker stays on!

@Jeff_the_Coaster_Guy posted:

This is directly out of the service manual and is correct.

OK cool.

One last thing I forgot to ask...does the KW output maximum power on either output? Or is the "190 Watts" split and each output only gives up 80 Watts?  (Also I read about these ratings being input, and to expect less at the outputs).  In other words, if I'm not using the "B" post could I get the full transformer output from the "A" or only half?

Jeff

All output is available from either throttle independently.

Alright, so after testing per the procedure Rob mentioned, the breaker took a while to warm up but after about 30 minutes of running two trains (one each on A and B side) with a total of between 5.5 and 6 amps, it started to pop every time it got to 6.5 or so. It would flicker,  trains would stutter and then run again.

So I replaced with a 10 amp thermal automotive type, and then separately put external 6 amp breakers in line with each output.

Ran like a champ after that, built up to around 7.5 amps constant output using some long lighted trains on each track and no issues. A derailment popped my 6 amp external breaker once, and a direct short with a 1 ohm resistor tripped the new internal breaker after 10 seconds. Still maybe a little fast, but I'll take it.

Thanks for the help.