Author Topic: Power Supply 56 and Keep Alives  (Read 283 times)

SCL1923

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Power Supply 56 and Keep Alives
« on: May 30, 2019, 08:19:07 PM »
Hi all,
I am about to order the Pwr. 56 supply for my HO scale layout.
Currently I have a Digitrax DCC power supply. I have two loco's with LM3s and TCS's keep alives with bridge rectifiers, both work perfectly. My question is when I install the PWR 56, and remove the bridge rectifiers, will the keep alives be able to handle the voltage either directly from the rails, or if I keep the motherboard in the loco, will the motherboard reduce the current enough so I don't have to worry about blowing up my Keep Alives? I found some info. here, but not exactly what I am looking for, or at least what I could understand. PS, Iv'e blown a small capacitor before and it wasn't pretty.

KPack

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Re: Power Supply 56 and Keep Alives
« Reply #1 on: May 30, 2019, 08:45:05 PM »
I'm not the expert here but you ought to keep the bridge rectifiers in place.  I run TCS keep alives with bridge rectifiers, powered by the PWR-56. 

-Kevin

William Brillinger

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Re: Power Supply 56 and Keep Alives
« Reply #2 on: May 30, 2019, 09:04:13 PM »
You do not need to remove the Bridge Rectifies to use a PWR-56, but you may get under voltage warnings.

The correct way to wire a keep-alive in any locomotive with an LM-3 is as follows:

- Bill Brillinger, RPUG Admin

Modeling the BNML in HO Scale, owner of Precision Design Co., and RailPro Dealer.


SCL1923

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Re: Power Supply 56 and Keep Alives
« Reply #3 on: May 30, 2019, 09:56:00 PM »
Thanks for the info. and agree I should not remove the bridge rectifiers. I've completed a couple of tests last weekend using my old, old DC power pack with expected good results and Iv'e seen the under power warning on the HC2 handheld before.
Let me expand this question to future installs of the LM3-S. For space and simplicity reasons, I don't want to install bridge rectifiers in any more loco's if the keep alives can handle the direct from rail DC PWR56 current. Anyone have a direct hard wired keep alive using the Pwr56?  I know just enough to fiddle with things and be dangerous!

William Brillinger

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Re: Power Supply 56 and Keep Alives
« Reply #4 on: May 30, 2019, 10:26:34 PM »
Quote
Anyone have a direct hard wired keep alive using the Pwr56?  I know just enough to fiddle with things and be dangerous!

Follow the diagram I posted. No Bridge rectifier. Works perfectly and the power source is not an issue. DCC or DC, it does not matter, this function is built into the LM-3, and the unit will run with LM's using a bridge rectifier with Keep-alive, or an LM with no keep-alive at all.
- Bill Brillinger, RPUG Admin

Modeling the BNML in HO Scale, owner of Precision Design Co., and RailPro Dealer.


CPRail

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Re: Power Supply 56 and Keep Alives
« Reply #5 on: May 31, 2019, 08:47:39 AM »
I concur with Bill & Kevin. I  have both 'flavours' running on the layout - with and without Bridge Rectifiers. Some of the ones with are LM-2S, some are LM-3S. All new installs are without Bridge Rectifiers.

I've had no issues running the units together. If you are using LM-3S you can dispense with the Bridge Rectifiers!
Ian Lisakowski
Modelling CP Rail & VIA in the early 80's
Rabid Winnipeg Jets Fan - Go Jets Go!!