Keep Alive for Paragon 3 sound decoder?

[Cajonpassfan]

I’d like to add a Keep Alive to my Paragon 3 N scale Mikado decoders. Anyone hazard a guess where to connect it to the decoder?
Pic below. The second pic shows how to do it on a larger (HO?) version of P3...
I did send an inquiry to BLI, no response yet.
Thanks, feedback appreciated.
Otto K.

[peteski]

The photo is not clear enough, and it only shows one side of the decoder.  Plus the more I think about this the less willing I would be to guess from a photo (even though I said that it is possible).  Going by my experiences evaluating the ESU decoders, I would rather have a sound decoder in-hand to try figuring it out.  Sound decoders are pricey and I don't want to be responsible for bad advice.

[jdcolombo]

FWIW, these are decoders that I took out of my BLI N-scale 2-8-2's.  I looked the board over both before and after taking it out of the engine, and I didn't see any obvious connection points for a keep alive, although it is possible that the bank of caps on one long side was supposed to provide some amount of keep alive for the decoder.  As usual, it should be possible to connect a keep alive to the blue wire (positive) and negative side of the rectifier caps (negative), but I wasn't sure where the rectifier caps were.  And since I was replacing the whole thing with an ESU LokSound, I didn't want to try to trace connections on the board.

Now Otto has them (or will, I hope, shortly, if the USPS cooperates).  It would be nice if BLI would post a photo or something like they did for the HO-scale version of this decoder.

I should also note that using BLI's photo, I added a TCS KA-3 to a friend's HO scale 2-8-2's with Paragon decoders inside.  Though the engines worked fine with my Digitrax system, they went crazy on my friend's NCE system, and when he called BLI about it, they informed him that adding a keep alive voided the warranty on the decoders and was not approved by BLI (they were long-past warranty anyway, but still - if you're going to post a photo on how to do it, don't then tell a customer not to do it).

Honestly - this company (BLI) seems schizophrenic at times.  I still love the 2-8-2's I have, but I love them more with ESU LokSounds installed.

John C.

[Cajonpassfan]

I did inquire with BLI “tech support”, and got a nice but useless reply, see below. I responded politely to the effect that *somebody* at BLI ought to know, since they built their brand around sound, a would they please inquire, but haven’t heard back yet.

Since  @jcolombo was nice enough to let go of these decoders, my intention is to put them to good use in a couple of old brass engines that have substantial sized tenders with plenty of room for either a keep alive or extra caps. Assuming the USPS cooperates...
To be continued...
Otto

[Cajonpassfan]

The photo is not clear enough, and it only shows one side of the decoder.  Plus the more I think about this the less willing I would be to guess from a photo (even though I said that it is possible).  Going by my experiences evaluating the ESU decoders, I would rather have a sound decoder in-hand to try figuring it out.  Sound decoders are pricey and I don't want to be responsible for bad advice.

Pete, I appreciate your comments and your reluctance. Perhaps when the P3’s get here, I can post pics of both sides...and take whatever advice I can get at my own risk😬
Otto

[peteski]

I did inquire with BLI “tech support”, and got a nice but useless reply, see below. I responded politely to the effect that *somebody* at BLI ought to know, since they built their brand around sound, a would they please inquire, but haven’t heard back yet.

Since  @jcolombo was nice enough to let go of these decoders, my intention is to put them to good use in a couple of old brass engines that have substantial sized tenders with plenty of room for either a keep alive or extra caps. Assuming the USPS cooperates...
To be continued...
Otto

I suspect that BLI's decoder designers are in China (maybe even a 3rd party company), so engaging them to pinpoint the attachment points for Keep Alive might not be a trivial matter.  If the designers were BLI employees in the U.S. office, this would be a simple task of walking up to their office and asking.  At least that is my speculation.    The other possibility I'm thinking of is that they know where to hook it up, but don't want the unwashed masses of modelers mucking around with their decoders, possibly damaging them (and giving BLI lots of repair work).

[peteski]

Pete, I appreciate your comments and your reluctance. Perhaps when the P3’s get here, I can post pics of both sides...and take whatever advice I can get at my own risk😬
Otto

Assuming that those 6 beige-colored caps in a row are all connected in parallel, the Keep Alive would connect in parallel with any of them.  JUst have to figure out the polarity. But that is  just a speculation and I'm making assumptions.  The safest way to give advice would be for me to have the decoder in-hand (for close examination).

[jdcolombo]

Here is the high-resolution photo of the decoders I took for Otto.

[ Guests cannot view attachments ]

My guess is that the four black rectangles to the right of the row of brown-ish caps are the rectifiers. 

Since these are diodes, they will pass DC current only in one direction, from the positive side to the negative side.  So I think that what you could do is use a multimeter with a continuity tester (or other continuity tester) to determine which side of the diodes are positive and which are negative.  You could then (I think - Peteski would need to confirm this) attach the positive wire from the keep alive to the positive side of one of the diodes, and the negative wire to the negative side; or you can attach the positive wire to the common positive supply for the functions (headlight) - also known as the blue wire.  Of course, there ISN'T a blue wire on this decoder, but the brown wire coming from the right side JST connector is the positive common (the equivalent of the blue wire on a normal decoder).

Of course, all this is speculation on my part.  Proceed at your own risk.

John C.   

EDIT:  Well, I wrote this and posted it before reading Pete's last reply, and of course, he's right.  The absolute easiest way to add keep alive would be to add it in parallel with the row of caps - IF those caps are in fact keep alive, and IF that keep alive is designed to keep the motor running as well as the sound circuit running.  Some on-board keep alive is there only to prevent sound dropouts, and is not connected to the motor circuit.  I'm assuming that what you want, Otto, is to have motor keep-alive as well as sound keep alive, and the only sure way to do that is to connect the keep alive to the rectifier circuit.

But if you want to be absolutely, positively sure, send one of the decoders to Pete for examination.  He's the one who figured out how to add keep alive to the then-new ESU board decoders now widely used by Intermountain and Atlas, and by after-market installers.

John C.

[peteski]

Here is the high-resolution photo of the decoders I took for Otto.

My guess is that the four black rectangles to the right of the row of brown-ish caps are the rectifiers. 

I agree with you as to where most likely the 4 bridge-rectifier diodes are.

John, I'm not sure how high of a resolution your original photo was, but the forum downsizes them to 1200 pixels across max.  Still, best way to do this is having the decoder in-hand, and under magnification on a brightly illuminated workbench. 

[jdcolombo]

I agree with you as to where most likely the 4 bridge-rectifier diodes are.

John, I'm not sure how high of a resolution your original photo was, but the forum downsizes them to 1200 pixels across max.  Still, best way to do this is having the decoder in-hand, and under magnification on a brightly illuminated workbench. 

Ah.  I didn't know that.  The original photo was taken with my Canon 70D, which has resolution of 5472 x 3648 pixels.

John C.

[peteski]

Ah.  I didn't know that.  The original photo was taken with my Canon 70D, which has resolution of 5472 x 3648 pixels.

John C.

Actually, it was downsized not even to 1200, but to 1024 pixels across. You can see that if you view the image in your post.  They do this to conserve forum's storage space.

[Cajonpassfan]

Well, the P3 sound decoders arrived in today’s mail, and looking at them, I’m no smarter then I was before. Here’s pics of both sides, not sure whether these will read any better than what John already posted. My most recent inquiry to BLI went unanswered thus far.
And yes, the goal here is to put these in old PRB brass steam locos, so I’d like the “stay alive” feature to provide power to both motor and sound, not just sound only. Ideas appreciated.
Thanks,
Otto

Well, dang, I’m unable to upload the pics. When I select a photo, I’m asked to choose a size, but regardless of what I pick, I get a “no image selected” result. Wth?

[Cajonpassfan]

Let’s try again.
Okay, got it working, my most recent iPad update is effing with me again.
But the images got resized very substantially so I’m not sure they are helpful.

[Cajonpassfan]

Good news. BLI sent me a nice and useful response, including a high resolution photo, see below, which I appreciated.
Good attitude, too. It’s good to know a manufacturer cares and strives for improvement.
So the next question I have as someone not familiar with soldering directly to the tiny board components, how do I do that without damaging the electronics? I looks intimidating...
I do have a small, fine tip rechargeable Isotip iron, as well as an adjustable temp Hako among others. Advice would be useful as I don’t want to fry the thing 
Thanks, Otto

[jdcolombo]

Well, honestly, that's about the best place possible for attaching wires.  It would take a lot to damage that cap, so I don't think you'll have any trouble.  Use the smallest tip you've got.  Pre-tin the wires from the keep alive before trying to solder them, and then put a tiny bit of solder on the tip of your iron, put the wire right at the bottom of the  joint between the cap and the board, and then just touch the iron to the wire.  Just keep the tip away from the chips next to the cap.

One trick I use for doing stuff like this is that I put a piece of the foam double-sided tape on my workbench to hold the decoder in place while I'm doing the soldering.  Much more stable than anything else I've come up with to hold it (don't want to use a vise!) and then you can brace your hand on the bench to get the iron tip right where you want it.

I guess I'll have to take back 50% of the bad things I said about BLI.  Although I still think the Paragon 3 is one weird decoder.

John C.