Author Topic: RP Keep Alive Installation  (Read 27411 times)

Alan

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Re: RP Keep Alive Installation
« Reply #15 on: October 04, 2018, 08:02:50 AM »
The fluctuating cap voltage measurement tells me you have them incorrectly wired into the circuit. The fluctuation in reading is interaction between the caps and your meter.
Alan

LK&O Railroad website

When I was a kid... no wait, I still do that. HO, 28x32, double deck, 1969, RailPro

emd_16645

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Re: RP Keep Alive Installation
« Reply #16 on: October 04, 2018, 09:39:30 AM »
That would be possible.  The negative side is wired directly to the yellow wire on the six pin plug, so that side should be fine.  The positive side I wired to a common light pin, expecting that would be adequate (it was conveniently located).  I will try rewiring that side of the board to tie directly to the blue wire on the 9 pin plug and see how it goes.  The board does have resistors installed to reduce voltage to LEDs so that may cause issues as well.  I'll report back soon.
Chris Bellows
Somerset Junction, 1980
somersetjunction.blogspot.com

emd_16645

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Re: RP Keep Alive Installation
« Reply #17 on: October 04, 2018, 10:02:19 PM »
I rerouted the + connection on the keep alive to directly connect with the blue wire on the 9 pin connector. With track voltage applied, it reads a steady ~13.5v. When power is removed, voltage reading drops about .1v per second with negligible load applied. My HC sim has been acting up in the past day, unable to test loaded conditions. Might be time to get a HC-2 soon...
Chris Bellows
Somerset Junction, 1980
somersetjunction.blogspot.com

Alan

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Re: RP Keep Alive Installation
« Reply #18 on: October 05, 2018, 06:43:41 AM »
That is the desired reading. The voltage drop is due to the LM drawing a small amount of current. I think you fixed it.
Alan

LK&O Railroad website

When I was a kid... no wait, I still do that. HO, 28x32, double deck, 1969, RailPro

emd_16645

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Re: RP Keep Alive Installation
« Reply #19 on: October 05, 2018, 11:50:53 AM »
Thanks for the help Alan.
Chris Bellows
Somerset Junction, 1980
somersetjunction.blogspot.com

emd_16645

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Re: RP Keep Alive Installation
« Reply #20 on: October 09, 2018, 08:27:44 PM »
Video of the keep alive install.


Works perfectly going forward. Dead shorts at 1% throttle in reverse. Probably motor is shot, I’ve never been a fan of the first generation genesis motor. Might be time to meet a Mr. Kato product.
Chris Bellows
Somerset Junction, 1980
somersetjunction.blogspot.com

Alan

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Re: RP Keep Alive Installation
« Reply #21 on: October 09, 2018, 08:40:07 PM »
Electric motors don't run in one direction then short out in the other. Mechanical impossibility due to the physical construction of a motor. You have a problem elsewhere.
Alan

LK&O Railroad website

When I was a kid... no wait, I still do that. HO, 28x32, double deck, 1969, RailPro

emd_16645

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Re: RP Keep Alive Installation
« Reply #22 on: October 09, 2018, 08:44:08 PM »
Electric motors don't run in one direction then short out in the other. Mechanical impossibility due to the physical construction of a motor. You have a problem elsewhere.

Any thoughts as to a culprit?
Chris Bellows
Somerset Junction, 1980
somersetjunction.blogspot.com

Alan

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Re: RP Keep Alive Installation
« Reply #23 on: October 09, 2018, 08:48:46 PM »
Is this on DCC powered track?
Alan

LK&O Railroad website

When I was a kid... no wait, I still do that. HO, 28x32, double deck, 1969, RailPro

Alan

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Re: RP Keep Alive Installation
« Reply #24 on: October 09, 2018, 09:07:43 PM »
Thinking about I can come to only one conclusion. There is an electrical path from one of your motor leads (gray or orange) to one or more of the other LM connections. I suspect it is to one of the outputs (white, yellow, purple, green). This would explain why it shorts at 1% throttle and not immediately upon power up.
Alan

LK&O Railroad website

When I was a kid... no wait, I still do that. HO, 28x32, double deck, 1969, RailPro

emd_16645

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Re: RP Keep Alive Installation
« Reply #25 on: October 09, 2018, 09:17:12 PM »
This is DCC powered track. I will check the motor connection points of the chip when I get a chance. I did have to resolder the yellow wire tonight (adjacent to the gray) so possibly something is crossing there. However I am not using any functions currently, all outputs should be zero. I do have one LED wired in (rear light), and I believe that it is in backwards (get a function short when activated), not sure if that could factor in.

I suck at electrical, must be why I went mechanical. Lol
Chris Bellows
Somerset Junction, 1980
somersetjunction.blogspot.com

Alan

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Re: RP Keep Alive Installation
« Reply #26 on: October 09, 2018, 09:54:29 PM »
I did have to resolder the yellow wire tonight (adjacent to the gray) so possibly something is crossing there.

That would explain it. Examine closely.

However I am not using any functions currently, all outputs should be zero.

Doesn't matter. Inside the LM at each output is a transistor which has the ability to block very small voltage from causing current to flow in reverse. But as the voltage increases at some point, usually around 0.6V, the transistor will go into breakdown, labeled V(be) in the datasheet, where current begins to flow backwards and the short occurs. Whether or not you are using that function is irrelevant. It is quite possible, due to the wiring problem, you are exceeding V(be) on an LM output when the throttle reaches 1%.

I do have one LED wired in (rear light), and I believe that it is in backwards (get a function short when activated), not sure if that could factor in.

LEDs wired in backwards simply do not light up. They do not cause shorts.

As politely as I can say this, it sounds like you have multiple wiring mistakes in your installation. Suggest you rip everything out and reinstall paying very close attention to the wiring schematic you included earlier in this thread. Make all your solder connections sound and thoroughly insulate all connections.

I suck at electrical, must be why I went mechanical. Lol

Hey, everybody sucks at something. That's why we have friends to help us out.
Alan

LK&O Railroad website

When I was a kid... no wait, I still do that. HO, 28x32, double deck, 1969, RailPro

emd_16645

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Re: RP Keep Alive Installation
« Reply #27 on: October 09, 2018, 11:11:30 PM »
Alan,

No offense taken, my soldering skills can't politely be described in public.  My understanding of LEDs is that it wouldn't cause a short, I only mentioned it because I'm aware of how flaky wiring can be.  I looked over the solder joints of the 9 pin harness and I'm not satisfied, so I have removed it.  The yellow and gray wires were touching so that would be the smoking gun.  I will re-wire the plug when I get a chance. 
Chris Bellows
Somerset Junction, 1980
somersetjunction.blogspot.com