I have the Bachmann Spectrum 4-6-2 K4 Pacific. Right out of the box, the headlight is very dim. You really have to look closely to see that it is on. I recently installed a sound decoder on another similar engine, for a friend. Same problem. Having two of them with the same problem, makes me believe that there could possibly be a inherent problem. Does anyone know where the resistor might be mounted, in the boiler or on the board in the tender?
Can anyone offer any help as to what to do to make the headlight brighter, or is it a loss cause?
Thanks for the help.
Ted
Common issue with certain Bachmann locos. The LED is down inside the loco smoke box with a plastic light pipe to bring the light up too the headlight lens. Look at the loco diagram.
Also, Bachmann uses a much higher resistor on the PC board. Somewhere around 2.5 k from some measurements I have made. Reduce the value to 1k and maybe even 800 ohms are a near standard value. 750 ohms will allow around 15 ma.
Most LED's are 20 ma max. 1K allows about 9 ma which is what many use. Parallel the resistor on the PC board or remove and put in a single resistor.
You can also put an LED right in the headlight fixture.
Notice, I did not say this would be easy.
Rich
This is the 4-6-0 which seems to be similar.
(http://i98.photobucket.com/albums/l267/richg1998/Spectrum%204-6-0/LEDlocolight.jpg)
The white dot is the plastic light tube. It is flush with the inside of the shell. It does not extend down to the LED.
(http://i98.photobucket.com/albums/l267/richg1998/Spectrum%204-6-0/Boilerinside.jpg)
Rich
Rich,
The light has a yellowish tint. So is it an incandescent or LED?
I will take your advice and take a look in the tender and try and locate the resistor. That would be the easy way out. Otherwise I may try to do a replacement. Now, how much work is it to remove the boiler shell? Any surprises?
Ted
The LED was not lit when I took the picture. It is a white LED, that I know. No idea what yours will look like when you get the proper light level.
All the components are marked on the PC boards. The resistors are only for lighting. They will be surface month components, that I know. Mine had labels for the motor leads, light leads, pickups. I used my multimeter on ohms to ring out the circuits. I have done electronic work for over fifty years so it is natural to just trace out a circuit,
If the circuit board has two green devices that look like resistors, those are inductors. A common misconception made by many.
Some just rip out the PC board and hardwire using a 1k resistor or a resistor that gives them what they like.
Rich
Hi Ted,
My first DCC ready Bachmann HO engine was the Pennsy K4 4-6-2. Like you, I was very unhappy with the brightness (or lack of) the headlight. I installed an NCE DCC decoder but it did not affect the brightness of the headlight any.
After working up the courage to remove the shell, I discovered that the light was emitted through a rather long light pipe that had a 90 degree bend in it. What I did to resolve the issue was to shorten, cut off, most of the vertical portion of the light pipe. I did not remove the light pipe, I carefully cut it off in place. I then bent the led up to where it was just below the remaining portion of the light pipe; this took several attempts to get the led positioned just right, but it worked. I don't remember if the original led leads were long enough to accomplish this or if I had to replace the led with longer leads (I think I had to replace the led). Either way I didn't have to replace any resistors and the brightness of the headlight was dramatically increased.
Good luck,
Rod in PA
Another very good solution. For many, it would be quite a challenge. There is no simple solution, though.
Sounds like you left the PC board in place and the new decoder would have the same effect as the stock Bachmann decoder. The resistor is still in the circuit.
I can see how this happened as there are probably no model railroaders looking at the finished product to see what the headlight looks like before releasing to the production department. Engineers design and send the requirements to a company in China.
Just look at the differences in the DCC tenders.
Rich
Thanks Rich and Rod for that good advice. This leaves me with a couple of options. I guess I am questioning if simply changing the resistor will do the job? That would be the easy way out. However with the design of the light tunnel, does that need to be modified as well? I would wonder what Bachmann would advise?
I am using a Soundtraxx decoder plugged into the original DCC On Board PCB.
Rod, how hard was it to remove the boiler shell? I have worked on a lot of locomotives, but never on the front end of a steamer. There are always those hidden screws, or secrets to the removal.
Ted
Here is what the 4-6-0 looks like. The 4-6-2 might be the same.
(http://i98.photobucket.com/albums/l267/richg1998/Spectrum%204-6-0/BottomscrewsB.jpg)
(http://i98.photobucket.com/albums/l267/richg1998/Spectrum%204-6-0/BottomscrewsA.jpg)
Take some photos as you do this. A picture is worth a thousand words and can eliminate a lot of useless chatter that sometimes can be confusing. I have seen this a lot. Yes I know, some just like to chat and that is ok also.
Knowing how all the pipes fit can be a challenge so take some clear pictures to put the loco back together.
Rich
Thanks Rich. That looks easy enough. Will let you know what happens.
Ted
Rich,
Looking at the engine, and your pictures, there is a big difference between the two. I did find a screw under the rear truck that appears to hold on the shell, but after unloosening it, I see no movement from the body. Also I do not see any screws in the front that indicate it would hold the front part on. Looking at the exploded view doesn't lend me any help. I wonder if it is possible that the boiler shell simply snaps off?
So Rod, if you are reading this post, can you tell me how to remove the boiler shell?
Thanks so much.
Ted
Happy Easter to all.
Hi Ted,
I'll try to explain how I removed the K4 shell, but first I'd like to say that some time after the light pipe modification, I installed a tsunami sound decoder which did not have any affect on the headlight brightness mod.
Now to remove the K4 shell. It's been a while since I've done this but I'll give it a try. First, look at the K4 parts diagram; it's on this web site if you don't have one on hand. Notice the screw just in front and centered on the female portion of the engine/tender connector. I believe this screw and friction are all that holds the boiler shell in place.
You can leave the engine and tender connected but be very careful, the connector wires can easily be pulled from their socket (that's another story). Besides, removing the tender is a lot more complicated that removing the shell. I use a thick, folded up bath towel to work on; you can roll the engine from side to side or upside down without having to pick it up.
Now back to the screw behind the connector. There should be just enough room to back out that screw without having to remove the female connector, if not you'll have to remove the connector (just two screws). Once the screw is removed, roll the engine back up right, lift up on the cab portion to about a 30 degree angle, gently push the entire shell forward (the bottom of the smoke box hooks onto the weight), the shell should now be free.
I hope this helps, let me know how you make out.
Rod
I strongly suggest disconnecting the loco and tender when you have to work on them. Very easy to do. Below is what I do. I gently pry the plug up a little with a small jewelers screwdriver.
(http://i98.photobucket.com/albums/l267/richg1998/Spectrum%204-6-0/4-6-0C.jpg)
The Bach-Man and some others use a tool from Micro Mark. Search the General and HO forum back about three weeks. Someone here already asked how the connectors can be removed without damage.
In a hurry or impatient usually results in a damaged plug/wire.
I use a foam cradle from Bowser trains for working on locos, tenders and rolling stock.
Again, a different decoder will not result in a brighter LED because the resistor in on the PC board.
My locos had as many as three resistors on the PC board for one headlight. Bachmann does like variety.
Rich
Hey Rod,
Got the shell off. Easy when you know how. I did remove the two screws for that hold the connectors in place, in order to remove the screw holding the shell.
The LED is a small one mounted to a circuit board, so it appears that there is no way to bend it upward like you mentioned. I am assuming that the LED fits close against the plastic light tunnel? I did power up the unit and the LED seems to be very bright, but by the time the light makes it's way up the tunnel, then the 90 degree turn, much of the brilliance is lost. So, I am thinking of a couple of options. One would be to leave well enough alone, and live with what I have. The other option would be to replace the current LED, and cut the light tunnel away inside the shell as you said. However, I would want to see if a different LED would be any brighter. If it isn't brighter, would removing part of the light tunnel, pointing the LED upward to the tunnel, make that much difference?
Stuff to ponder. Happy Easter.
Ted
Rich,
Yes it best to disconnect the tender. Yours, as I see in the picture, has the standard drawbar, the K4 has the wishbone type drawbar. I would prefer your type.
I do use the foam cradle as you suggested. To many disconnects could lead to a damaged wire. "Carefully" is the word when plugging and unplugging.
Ted
Hey guys,
I was able to remove the headlight assembly without any problems. Now, in measuring the voltage for the LED, I measured 1.93vdc. Isn't that a little low for a standard LED, or should I be able to find one to match that voltage?
What I am thinking is to drill out the headlight lens, insert a LED into the assembly, and run the wires down to the current PCB on the frame. Does that sound like a possible fix? Or should I cut the light tunnel off and hope that a brighter LED will do the trick?
Ted
The voltage is not a primary concern. The current is. I have put as many as three LED's in series with one resistor and never had to worry about the voltage. I started with 1 k and adjusted up or down a little while watching the current. Brightness can change some but not much.
Some people are putting in Super Bright 20 ma LED's and have to increase the resistance to maybe as much as 2k.
Some LED's you buy can be a the 25 ma type but again, just watch the current.
Put your meter on DC current and connect in series with one LED lead and the lead from the decoder.
I think I already provided a link or two on how to use a multimeter in model railroading electric.
You want at least 10 ma to 15 ma of current.
LED's are current operated devices.
Light bulbs are voltage operated devices.
Many confuse the two issues. I have known a few who burned out a bunch of LED's as they were thinking light bulbs.
The below is only one link on LED's and bubs as used in model railroading but it should help a lot.
http://www.members.optusnet.com.au/nswmn1/Lights_in_DCC.htm
If you probe the PC board with the voltmeter, you will see about 12 vdc from the decoder and eventually see the same low voltage where the lead to the loco headlight leaves the PC board. Pin 6 on the eight pin connector is 12 vdc from the decoder.
Rich
Quote from: tmiller on April 01, 2013, 01:53:21 PM
What I am thinking is to drill out the headlight lens, insert a LED into the assembly, and run the wires down to the current PCB on the frame. Does that sound like a possible fix? Or should I cut the light tunnel off and hope that a brighter LED will do the trick?
Ted-
I wouldn't put a brighter LED in your loco because you may wind up with some of the light leaking out where you don't want it to. Installling an LED in the headlight housing and connecting it to the PCB ought to work just fine. Depending on the headlight lens, you might want to consider putting a surface mount LED inside and keeping the lens.
Whatever you do, good luck with the project.
-- D
Ted,
I do exactly what you have suggested. Putting the LED directly in the headlight makes a huge difference. You can cut the plastic lens in half (carefully) to make room for the LED. Even better is to put in an after-market lens, if you can find one.
If you check my past posts on my 2-8-0 projects, there should be some useful photos to help you with this.
I use my own 1k ohm resistor, placed in the gap between the split frame and the back of the smokebox front. There is about a 1/4" dead space in this area.
I have reused the stock resistor, with good results, as well. Remember, polarity matters.
In the prototype, steam loco headlights weren't very bright. However, I like it bright when running models. Just looks better in my opinion.
Regards,
Jonathan
Jonathan reminded me about the below link I had stored the first day I saw it.
http://www.bachmanntrains.com/home-usa/board/index.php/topic,22055.0.html
Everyone, store the link in Favorites. I have seen questions before about dim lights in Bachmann locos here and other forums.
You might also save the page to your PC. If the Bachmann forums ever go through a modification like they did a few years ago, this page might disappear. That way, all you have to do is click on the file you save to your PC and this page will open up as if it still existed in the Bachmann forums. I have done that with some personal MR sites that went away and I still have all the data. Sometimes people change their Photo Bucket site and their pictures disappear from the forum messages.
Take advantage of the power of your PC. You do not have to be a PC guru. Compare it to putting a large file cabinet in your back room office to store important papers.
Rich
Hey guys,
A lot of good information being passed around on this thread. It is also an educational experience for me.
Here are my thoughts and concerns:
I do agree that adding an LED out in the open in the boiler unit might be a mistake, with a lot of light bouncing around inside. The only correct way is to mount it in the headlight assembly. My concern is eliminating the light pipe from the light housing. I am assuming that it is a square piece of plastic inserted and glued into the housing. The light from the LED travels up the pipe, and is diffused at a right angle through the lens.
The pictures of the 2-8-0 headlight assembly do not match what I have. That assembly is out in the open, and much easier to work with. In my situation, the light pipe is what fits through the top of the boiler shell, and lines up with the LED inside. My biggest concern is how to remove the light pipe, without damaging the headlight assembly. It would have to be drilled out, as I am sure it is glued in. It would be like working on a swiss watch. Small to minute in size. Removing the light pipe seems to be the biggest hurdle right now.
(http://i1056.photobucket.com/albums/t367/tedm453/DSC_2681.jpg)
Then comes the issue of finding an LED that small. I am going to a train show this Sunday, so will seek out the LED guy to see what he has.
Now, as for the resistor, do I have to do anything with it, since it is most likely on the PCB in the tender? My guess is to simply connect it to the two wires coming from the decoder, through the engine.
Still pondering this delicate operation.
Jonathan,
Just had a thought after looking at your 2-8-0 installation, which by the way, you did a great job.
Why not just leave the light pipe intact, and drill out the back of the light assembly. Then run the wires out the back, down into the boiler shell, much like you did. They would hardly show, and wouldn't look bad otherwise. That way I should be able to keep the lens intact in the front.
That sound like a game plan. What think?
Ted
Ted-
You'll need to drill out the light pipe. Either use a Dremel style tool at a low speed, for maximum control, or a pin vise which will allow you to hand drill it. Keep in mind that you don't need a perfect job as the headlight itself will cover the hole in the top of the smokebox and the bottom of the headlight fixture.
You can use a surface-mounted LED or a very small LED with legs. The smallest regular LEDs I've seen are 3 mm but I understand there are some as small as 1.88 mm. That's about .076 inch diameter. As important as the size is the color. You can find bright white, sunny white, cool white, warm white, yellow-glow white and probably others. Regular white LEDs tend to be quite blue which is unrealistic. You need to paint a little thinned yellow on those. I would use either a warm white or yellow-glow for electric headlights.
-- D
Don,
Thanks for the reply. I am curious as to your thoughts on drilling out the light pipe, vs drilling out the back? That was my original idea, but I figured it might be a real chore. I guess the only benefit of drilling out the pipe, would be that all the wires would be hidden. And by drilling out the back, I would retain the lens up front, which may not be important.
I do need to measure the opening to see what size I need. I agree going with the yellow-white. Right now it is a yellowish tint.
Hopefully I will find a suitable LED Sunday at a local train show.
Thanks for your advise.
Ted
Ted-
Well, I think that feeding the wires through the bottom of the light housing conceals them. Yes, many electric headlights on locomotives which were built before electric headlights, and some which were updated with more powerful headlights had exposed conduit (what we call BX today) but our two wires snaking into the smoke box don't look like one BX cable which wouldn't go into the smoke box in the first place. So I think the bottom feed works best and looks best. And I think you can still use the lens even if you drill out the light pipe and bottom feed.
-- D