Y3 on DC

Can't speak directly to this, but I've sent Jon one of my offending MRC DC power packs last week.  Let's give him some time to figure out exactly what's happening and hopefully come up with a solution.

Rusty

Tom,

What size capacitor are you using?  I may be able to suggest a value in a week or so that may solve your concern.

However, given the environment and locos you are running; maybe a "gut" is in order.   Was worth a try to see how the Y3 ran before you removed the electronics in the loco, and your feedback and efforts are appreciated!

Jon,

There are two caps, both are ICC 2200uF 50V.  Electronics is not my forte so I can’t tell you what the resistors is, however I can give you its strips; brown, black, red, gold.  I don’t remember where I found this circuit; it was a long time ago.  I was looking through my model railroad electronics yesterday and couldn’t find it.

I remember in my early days of converting to DC that filtered was supposed to be better, but with the pitfalls of this circuit, I soon gave it up.  I’m not against using filtered DC if it can be tamed.

Tom Stoltz

in Maine

The O guys have a related problem trying to control a DC-only engine (perhaps a smaller scale mining side track), using an AC controller that starts at 5.5VAC.  One method is to add a string of rectifiers to the DC output.  Each rectifier drops the voltage by 0.7-0.8V.  So a string of 5 would lower your DC voltage by 3.5-4 Volts.  Of course it does this on the low end and high end.  A 6 Amp rectifier goes for less than 50 cents each and maybe 1/2 that on eBay.

Thanks Tom, I will let you know my findings after my tinkering. 

Hi Tom,

Yes, a bit of tinkering was accomplished...  I found that the Y3 will enter DC mode with the MRC Power 6000 with only a 100uf cap on the output.  I used 2x 220uf / 35v caps in series (negative leads tired together, positive leads across the track rails).  This arrangement of the caps provided a non-polarized configuration.

The only variable using ~100uf - is this arrangement works for a loco when there are not lighted cars on the track.  As soon as you add more load, then the cap needs to be larger.  I also tried some lighted pass cars behind the Y3; and increased the cap to two 470uf / 35v in the series arrangement described above.  This results in about 235uf capacitance and seemed to work well.  Around this value may be a fine place for you to start should you wish to keep the faith on the current electronics package.

If you continue to increase the cap value, then you will start to see the issues you had with some of your other locos running too fast.  I am not sure the resultant ~235uf value would be very detrimental in general to your locos; but you will know once you give it a try.

If you wish, email me off forum, and I will send you an assortment of caps to try.  I am curious as to what you find should you try this.  Also, I am trying to improve the DC detection process in code, but that does not help you as you indicated you did not wish to open the loco to reprogram.