The Mystery of Electronics

[Woody Elmore]

Jon: the solution is simple. Put the shells back on the darn things, go out and buy two more silver box engines - be sure the boxes are different sizes. Then, hopefully, you have two pair of double headed diesel engines.

I wish I knew more about magic smoke. The circuitry controlling my furnace gave off magic smoke a year ago when we had a power surge.  So now I know why electrical engineers get the big bucks; they know about "magic smoke." Hmmm, what other secrets do they harbor? Maybe there's a "DCC Devil!"

[jward]

there is a dcc devil.....lol. he's the one who makes you have to give your track the white glove cleaning in order for things that worked perfectly well on dc, to work on dcc. he's gotten us to pay big bucks for a command station, more big bucks for enough decoders to equip our fleets, yet more on expensive track cleaning cars, and auto reversers to do the job of a $3 toggle switch. that devil is costing me almost as much as my car......lol

[jonathan]

I'm starting to feel like Tommy Chong, "It's all a conspiracy, man!"  I keep telling myself, just one more engine and I'm done!  Who am I kidding?  There's always just one more to reach Nirvana, isn't there?

Regards, and running outta room in my garage,

Jonathan

P.S.  Jim, if you're out there, which resistor do I bypass?  Never hurts to ask...

[Atlantic Central]

Jonathan, what you have is two completely different production runs with  different light board designs.

How much different are thein speed? Have you actually tried to run them together or did you just run them uncoupled and one was faster.
Try them coupled and see iff they really fight each other or if they run fine.

I would have to see the borads in person to figure out if one could be modified to match the other. Are you sure the newer one is not DCC?

Did it come with any kind of extra plug for that white connector? That secondboard may be a decoder. A dual mode decoder will give different speeds than a DC only locos.

Sheldon

[Stephen D. Richards]

From the pictures, it appears that you have a cheaper P2K type Decoder with an 8 pin sound plug available.  The top board is a basic DC light circut board with an eight pin decoder socket.  I have several of both in various production runs and if the one on the bottom is a DCC decoder, then it is a dual mode and will run on DC.  I would get a decent eight pin decoder and plug it into the top board.  Then you can set the speed and run them together with no problem.  (Depending on the DCC controller you have that is!)  Hope that helps.  Stephen

[Atlantic Central]

Stephen,

Based on the OP's orginal information, I do not think he is using DCC.

I did not reconize it for sure because I do not use DCC and have never been inside a Proto loco that came with DCC, but I thought that might be the case when I saw his pictures.

My other question still stands, did it come with a jumper plug to remove the decoder?

Dual mode decoders, while they do "work" on DC, often provide poor performance depending on the type of throttle you have. Not using DCC?, get rid of the decoders. That alone will likely solve the problem.

Sheldon

[jonathan]

To clarify further,  I run DC.  So, I am incredibly surprised that that faster loco may have a decoder (9 pin?).  I did not look for a jumper plug as I was unaware it may be a DCC loco.  Certainly didn't mention DCC in the ad when I ordered it. 

Goes against my limited logic that the DCC loco would be faster than the DC loco.  And no, they are so far off in speeds, one couldn't MU them without doing serious damage.

Will look for a jumper plug in the box.

Regards,

Jonathan

[jonathan]

After, consulting the inst sheet, the extra board in the faster SD7 is just a PC board not a decoder.

I think the answer is to put these two engines away until I switch to DCC.  I have plenty of other toys to play with until then.  Thanks for trying to help, everyone.

Respectfully,

Jonathan

[BestSnowman]

The faster locomotive does not have a decoder, the smaller board is just a DC plug that would be removed to install a decoder.

I would guess that the light board in the first one is at issue, you could try wiring up the slow one directly from pickups to the motor to see if it speeds up. That way you would know for sure if its the lightboard or something else.

[Stephen D. Richards]

Sheldon, I wasn't sure either.  It is difficult for me to tell by the pictures because I don't know enough about those boards.  I have had several though and some decoders that appear very much like the bottom picture he has.  That knowledge came about by trial and error.  Mostly my error!  lol 

jonathan, I'll check my surplus.  I might have one of the older boards if you need it.  Stephen

[pipefitter]

... I would guess that the light board in the first one is at issue, you could try wiring up the slow one directly from pickups to the motor to see if it speeds up. That way you would know for sure if its the lightboard or something else.

That's a great plan. On the slow loco picture I see two groups of four diodes. Before DCC days one would make constant lighting in a locomotive by wiring four diodes in a "bridge" (I forget the name), and the bridge in series with the motor. There would be a constant voltage drop of 1.5 volts across the bridge which would power 1.5v gow/gor bulbs full brightness at anything above 1.5v on the track. Further circuit connections would yield directional lights as well as constant intensity. I have several Athearns set up this way, i.e. a GP-9 with constant light in the cab and directional headlights. Only thing is these locos take a significantly higher voltage per unit speed vs unmodified locos. Wasn't a problem for me as I always ran one powered loco with additional ones being dummies.

When I saw those groups of four diodes, I thought that might be what's going on with your slow loco. I believe this circuit is still being used today in some way with LED's. However... there is a jumper wire in the middle of your slow loco board which is labeled "CUT FOR DC". I wonder what that indicates?

Robert

[jonathan]

Actually it reads, "cut for DCC," for when you install a decoder I suppose.  Both locos do have constant/directional lighting... nice but not as nice as double-heading would be.  That's why I keep thinking about bypassing the resistors somehow.  I know I could pull the board completely, change the bulbs, and hardwire the motor to the pickups, like Matt suggests.  Just seems a little radical.  I was hoping to create a bridge for the motor, with a wire or two, something I could remove if/when I install DCC en mass.  My fault for assuming there was something simple I could do. 

All of you are great for putting so much grey matter into it.

Stephen, thanks, but I don't think the board is faulty, I think they just made it that way, so DCC would be easy (plug and play).  Now, if you have a board without all the little diodes and resistors... 

Regards,

Jonathan

PS, Stephen, did you really mean replace the faster loco's board, with an older board,  to match the slower one?

PPS.  I could run just two wires from say the front right and left pickups to the motor, all on top of the board...  PROVIDED I get the whole positive/negative thing right.  The right rail is positive?

[pipefitter]

... PPS.  I could run just two wires from say the front right and left pickups to the motor, all on top of the board...  PROVIDED I get the whole positive/negative thing right.  The right rail is positive?

I think you would be better off bypassing the board, just in case. Like accidentally hooking a guzinta to a guzoutta or not seeing a hidden circuit path. Although there doesn't appear to be any delicate components there like the all the little surface mount bits on the fast loco board. Just my 2c

Edit: Yes right rail positive = forward motion is the convention

Robert

[jonathan]

Success!! Well... sort of...

My temporary solution was to bypass the front pick ups (slower loco) and attach them directly to the motor tabs on the circuit board.  No soldering required.



Did it work?  I can set the engines two inches apart on the track, apply power, and the engines will run, at any speed, two inches apart from one another--never moving a bit closer or farther apart.  Cool.

Drawbacks?  The lights do not come on, in either direction.  That just means the slower loco (former) will never be the head engine.  I can live with that for now (get behind me, Dark Side). 

I could never have noodled this through if it hadn't been for the great brains on this forum.  Thanks-a-million!

Here's a clip of the train in action, if you're interested.



That headlight is not flickering, it's called poor camera quality. 
Regards,

Jonathan

[BestSnowman]

I guess thats why they changed the lightboard from production to production

If you ever stumble upon one of the newer lightboards you could get your lighting back on the "slower" (though I'm not sure it still fits the moniker).