Some time ago I picked up a P2K SD7 B&O #1830 at a train show. Nice Loco. A year later I picked up another P2K SD7 B&O #1829 at another train show. What luck! I can double-head these engines. Great! Only the #1829 runs at exactly twice the speed of the #1830. Surely somebody is trying to have some fun with me. I am pulling the shells off to have a look at the circuit boards. Please tell me there is a resistor somewhere I can bypass.
The gears in both locos seem to be the same sizes. I can hear the motor in the faster locomotive is also running faster than the slower locomotive. Each day, the call to the dark side is getting louder.
Regards,
Jonathan
Until recently Proto was switching the final gear ratios with every release. I believe they finally settled on 18:1.
Is this a DCC ready, or DCC installed engine?
DG
Both engines are dcc ready (paperwork says so).
Interesting about the gear ratios. I just looked at the gears. I didn't pull them out and count teeth.
The newer one (guessing, based on when I purchased) is the faster locomotive (#1829).
Jonathan
I don't think that you will see any difference in the motor gears. The difference will be, if any, in the truck gears. Pop the truck gear cover and compare the two. My thinking is you will find one or more the gears to be different.
Speed gearing is in the trucks for most every diesel engine. If you have to, count the teeth. :)
Good luck!!
Thanks, guys.
I'll bet your right. Something tells me I have two nice locos that I will never be able to double-head until I switch to you know what. At least each is strong enough to pull a twenty-car train all by its lonesome.
Regards,
Jonathan
(http://i642.photobucket.com/albums/uu146/jsnvogel/Rolling%20Stock/DSCN1923.jpg)
(http://i642.photobucket.com/albums/uu146/jsnvogel/Rolling%20Stock/DSCN1925.jpg)
What color boxes did they come in? If one is blue and the other silver, they might well be geared differently. The silver boxes are the newer ones and some models did recieve some changes about then. Were they new or used? One could have a bad motor.
Are you sure one does not have a decoder installed by some previous owner? A dula mode decoder would run dramaticly differently on DC than a regular DC loco.
Sheldon
If your a long way from going dcc why not add a resistor to slow the first unit down?
NM
Quote from: NarrowMinded on February 18, 2010, 09:17:11 PM
If your a long way from going dcc why not add a resistor to slow the first unit down?
NM
If you go this route, calculate the wattage needed for the resistor. The resistor could get kind of hot. Even then, this could be iffy.
Lex
I forgot about turning all that extra energy into heat, it would likely be a pain to get the right resistor to match the speed anyway.
If it's not the gearing of the units then it could be the motors are differant, maybe one has more windings then the other which would make it run at a differant rpm on the same voltage.
just my 1.5 cents
NM
and I was beginning to wonder about the subject of this thread. ;D ;D ;D ;D
There is no mystery involved with electronics. All electronic components contain magic smoke, which makes them operate. The key to working with electronics is to NOT let the smoke out.
Someone may have let the smoke out of one of your engines.
Wow. You have given me some real food for thought.
Just to clarify: both engines were bought new and have no decoders. Both came in the silver boxes. However, the slower engine came in the larger silver box, where I was required to assemble the shell to the frame. The faster locomotive came in a smaller silver box; the shell was already attached to the frame.
The gears all appear to be the same size, but I haven't counted teeth.
I have been pretty lucky, in that all my new loco purchases, to date, have had no real problems. Murphy could have finally caught up to me, and just maybe I have a bad motor in the slower engine. Strange though, it pulls just as well as the faster engine, just a lot slower.
I appreciate all the great suggestions. I think I'll have to pull apart the slower engine, test the motor and other parts, and see if I can't find some logical reason for its behavior. Could be it was made that way on purpose. These motors "appear" to be the same ones that Athearn uses. I do happen to have a new Athearn motor I put in an old GP35. Would be happy to sacrifice the Geep if the new motor will fit. Wouldn't that be something...
Regards,
Jonathan
It could be as simple as adjusting the tension of the brushes. A brush may be too tight, or too loose. Lengthening or shortening the spring pushing the brush to the commutator could make a world of difference. While powering the motor, ( out of the engine ) play with a spring and see if adding or decreasing pressure speeds up the motor
PD:
This makes sense. When the shells were off both locos, the slower loco's motor was running at slower rpms with the same amount of current applied to both. I figured if it were a gear difference, the motors would be at the same rpms, given the same amount of current.
These engines are nice runners. I was hoping to avoid a complete disassembly, on the chances I might break something. However, it is going to be necessary to take the engine to nearly parade rest, in order to get at the motor.
I will be extra careful. Never worked on a Proto before. There are more wires and little extra pieces than other locos it seems. I will check and mark the circuit board, so all the little wire connections go back where they belong when I'm done.
Thanks a million.
Jonathan
After breaking down, monkeying with, and putting back together the slower locomotive, I cracked open the faster locomotive.
This is why I named this thread after mysterious electronics.
The first shot is the board on the slow loco:
(http://i642.photobucket.com/albums/uu146/jsnvogel/Projects/DSCN1927.jpg)
Here is the fast loco board:
(http://i642.photobucket.com/albums/uu146/jsnvogel/Projects/DSCN1928.jpg)
Holy cow! What is that weird thing on the left? I find if I disconnect it, the engine no longer runs.
So I've got two identical engines, mechanically speaking, but their wiring is totally different. Who knew?
Thanks for reading. I'm still learning I guess.
Regards,
Jonathan
PS Electronics are INDEED mysterious... especially when I hear about things like "magic smoke" :).
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!"
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
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...
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
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
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
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
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
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.
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
Quote from: BestSnowman on February 21, 2010, 09:35:59 AM
... 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
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?
Quote from: jonathan on February 21, 2010, 02:57:25 PM
... 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 :D
Edit: Yes right rail positive = forward motion is the convention
Robert
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.
(http://i642.photobucket.com/albums/uu146/jsnvogel/Projects/DSCN1929.jpg)
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.
(http://i642.photobucket.com/albums/uu146/jsnvogel/Rolling%20Stock/th_DSCN1931.jpg) (http://s642.photobucket.com/albums/uu146/jsnvogel/Rolling%20Stock/?action=view¤t=DSCN1931.flv)
That headlight is not flickering, it's called poor camera quality. :-[
Regards,
Jonathan
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).
Jonathon,
The difference between the two PCB boards:
The slower locomotive is using 4 diodes to produce a voltage drop of 3vdc for the directional headlights, which are rated at 3vdc. This is 3volts that the motor never sees.
You jumped out the diodes when you ran jumpers from the truck pick-ups to the motor.
The faster locomotive is currently wired for Headlight LED's, or 12volt bulbs using a diode
for directional headlights. (one diode per bulb). You can either jump out the diodes, like you have done alread, or remove them and jump them out with small wires.
Scott
Scott,
Thanks for the great info.
Since both locos now run at exactly the same speed, I will let sleeping dogs lie for now, if I am doing no electrical damage to the motor. If/when I add decoders, then I can quickly remove my jumpers, and adjust the speed steps so the locos can MU together. Hopefully, the lights will still work. If I understand (that's a big IF), not enough (or no) current is getting to the diodes to turn the lights on. That's OK with me.
I suppose if I wanted to tinker some more, I could wire two temporary 12v bulbs in parallel. I would have lights on in both directions, that get dim and bright along with the speed of the engine. I gotta stop monkeying with these things before I break something. Although, I do have a small bag of lift rings, just in case. :)
Respectfully,
Jonathan
Jonathan,
Each diode produces a voltage drop of .75vdc, add another diode at that drops
another .75vdc, thus the two diodes produce a voltage drop of 1.50vdc. Add two
more diodes and that's another 1.50vdc. Four diodes together produce a 3vdc
voltage drop, thus your power pack is set to half throttle, but your motor is only
seeing 3 volts, thus the other 3 volts is being dropped across the diodes to produce
a directional headlight bulb rated at 1.5 volts. I use one diode (1amp, 50piv) and a
minitronics 12vdc bulb for the headlight, which only lights in the forward direction. If
you want a reverse headlight, use another diode, in reverse polarity of the first diode,
and another 12volt bulb. Since the diode only drops .75vdc, you will not notice any
difference in motor power. For DCC, each output of the decoder for headights are rated
at about 2vdc, so you can use small bulbs or even LEDs. (when using LED's, don't forget
to add a current limiting resistor to one lead of the LED!!)
Scott
Jonathan, If it ain't broke, don't fix it!
Jonathan, actually I meant either or! However, I learned more from this thread about those DC boards and may keep them for myself! lol Just kidding, if you need an older board let me know. Although it sounds as if you've got a handle on this thing. Maybe if I sent you mine....you could fix them. lol Stephen
You know, it's funny. All this tinkering has got me in good with my LHS. When ever they get a return, or a loco that doesn't work (usually bumped too much in shipping), they let me fix it, and I get a small store credit. I only do simple, obvious corrections, parts that are missaligned or lying loose inside the shell. This is becoming too much fun, and keeping me from finishing the scenery on my layout. Gotta knuckle down and make some trees and start lighting my structures.
I love this hobby. Glad I gave up golf.
Regards,
Jonathan
I'll second that! Stephen
My wife told me it was time I started playing golf again.
That was on the way home from the Train Show.
Clif
uh oh. Someone's in trouble ;D ;D ;D ;D ;D
PD,
I was in a touch of trouble until I took her out to dinner. Of course, it didn't hurt when I explained that she had spent more than me. She's getting into this train stuff and I love it.
Clif
PD,
I know this is "off topic" but, have you heard from Yampa Bob lately ???
Clif
no
Here is a link to constant voltage lighting circuits. A single bridge rectifier that has four diodes drops the voltage 1.5 volts. I first saw this idea many years ago in a model railroader magazine.
A picture is worth a thousand words.
http://www.mrollins.com/circuit.html
Lex
Lexon,
That's almost easy to understand. I added that to my 'favorites'. Thanks.
Jonathan
I just used a mircoelectronic's forward reverse light kit for daughters HO percy, She wanted lights. these units are around $14 bucks you could remove the boards from both locos and install new kits in both.
Just an idea,
NM
NM,
The SD7s will probably stay 'as is' until I move to DCC (someday).
However, I just started work on a Mantua Mikado I received for my 12th birthday (many moons ago). If all goes well, this would be a perfect loco to experiment with forward/reverse lighting. I superdetailed a Varney tender to replace the original long haul tender. The 'new' tender has a reverse light.
Am I restricted to the size/wattage of bulbs with the microelectronics kit?
Regards,
Jonathan
If you go the DCC route, I would use a GOR 12-16 v bulb with a 22 ohm 1/4 resistor