i was just about ready to reply to your DCC 'error' but i saw that you had already corrected it, lol
Yes, that was backwards, 6 years ago. Notice in the post AFTER that (after Pakuna Matata's post), it was right.
MTH is positive function, negative common. Opposite from DCC. Current source vs current sink. SO reusing their LED boards is next to impossible, probably easier to put your own LEDs in. On a part with a single LED, no big deal, just flip the wires, but on the boards that have the headlight and independent markers or number board lights all integrated on one PCB, cutting traces and adding jumpers to get them all together in a postive common may not be easy. But if you swap out the board, fitting the individual LEDs so they shine in the proper places becomes more difficult, though more of a mechanical issue.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
rrinker ....MTH is a positive common, whereas DCC decoders are all negative common (the blue wire is negative).... --Randy
....MTH is a positive common, whereas DCC decoders are all negative common (the blue wire is negative)....
I think you got this backwards.
DCC Blue wire is always Common positive (+)
Wouldn't surprise me if MTH had it backwards...they don't like to make anything industry standard which probably why they haven't done so well in the HO market.
Also part of the reason I refuse to buy their products. I shouldn't have to completely rework the lighting in a model if I choose to change/add decoders for sale price of their models.
Colorado Front Range Railroad: http://www.coloradofrontrangerr.com/
Maybe I should move the conversion of my FAs up on the pending project schedule so I can take pictures and document it. There won't be as many LEDs, since I have no ditch lights, and being cab units, there is only a headlight on the A, the B has no lights at all.
I haven't heard anything new, so I assume MTH will cease existing as the same company in late 2021. There may be a buyout, and parts of the company may survive with different people.
Anyone looking to get support from MTH would be well advised to do it sooner rather than later.
It takes an iron man to play with a toy iron horse.
Hi
I have just discovered the same issues on my MTH Dash 9's that I purchased recently.
How did your conversion to LokSound go? Were you able to achieve a good result? I would very much appreciate any feedback/advice if you are willing to share.
Many thanks
John GeddesVancouver, BCjngeddes@icloud.com
If you hit the Yahoo group I mentioned and grab the relevant document, they show where to cut traces on the MTH light boards so you can wire around the negative common so teh LEDs can be seperated as needed (it's DCC that uses positive common - blue is plus, the function drivers are all open collector current sinks).
Randy:I was aware that the MTH locomotives are positive-common wiring, as opposed to the negative-common used on DCC. Of course that complicates matters greatly, as it means completely rewiring much of the locomotive. My EE expertise will come in handy, I guess. It also means that certain lights can't be given their own operating channels.I was finally able to contact an MTH representative, and they told me the voltage rating for the LEDs was 2.7 volts. My standard fair for calculating resistor value is assuming a current of 15 ma, and a source voltage of 18 volts (I know the standard fair for DCC in HO scale is 12-16 volts, but I like to shoot higher for safety).Given that, it looks like 1.2k Ohm resistors are my answer.
While LEDs vary in characteristics, the voltages are somewhat standard - there's no such thing as a 12V LED - that's just an LED that comes with a resistor built in to work on 12 volts. White LEDs are typically 3.5V, red and green and yellow usually around 2.1 volts. What varies is the brightness at a givven current level, high efficiency LEDs are super bright even with just a couple of milliamps, regular ones may need coloser to half their maximum before they are reasonably bright. Maximum varies, but a 3mm and rectangular through-hole types usually top out at 20ma, suface mount ones may be more like 10-15ma max. You would never want to run right at the max value anyway, so of you calculate for half or less, it will always be safe and not blow up the LED. You could always change to a lower value resistor (increase the currnet) if it's not bright enough. Or a higher resistor and use even lower current if the LED is too bright. The danger is too much current, if you use too large a resistor and not enough current flows, the LED won;t light, but even regular ones glow visibly with 1ma.
Where there may be a wiring issue is I THINK (have not tested this - but I believe I saw it on the Rick Bell RPM Clinics Yahoo Group - in fact ther eis an article there on converting an MTH loco to a standard DCC sound decoder) MTH is a positive common, whereas DCC decoders are all negative common (the blue wire is negative). It doesn;t matter what lead the resistor is on, but all of the LEDs around the front of the loco are probably commoned on the mounting circuit boards so one 1 wire has to run to the MTH board. This cannot be easily switched for DCC - the traces on the LED boards need tobe cut and new wires soldered on to make the common for the DCC blue wire plus a wire to the + side of each LED. Again, it does not matter which side the resistor goes in, as long as it's there, but I like to do them all the same for consistency's sake.
tstage Michael, Good choice in alternative sound decoders for your locomotive.
Michael,
Good choice in alternative sound decoders for your locomotive.
Yeah, ESU is usually my go-to for sound decoders. I love the flexibility that they offer and they have excellent motor and function control too.
tstage That said, I would think that MTH would use standard 3mm 1.5V LEDs, since they are the most readily available. And I'm assuming that the resistors are found and soldered on the Protosound 3.0 board?
That said, I would think that MTH would use standard 3mm 1.5V LEDs, since they are the most readily available. And I'm assuming that the resistors are found and soldered on the Protosound 3.0 board?
About half of the LEDs are surface mounts (ditch lights), while the other half are rectangular through-hole LEDs. The resistors are soldered to the PS3.0 board, though which resistors they are, I could not say as the board is far too cluttered to figure out what goes where.
Good choice in alternative sound decoders for your locomotive. I'm sure that someone will be able to give you an answer to your question. You could also try and contact MTH directly with your query.
Tom
https://tstage9.wixsite.com/nyc-modeling
Time...It marches on...without ever turning around to see if anyone is even keeping in step.
I recently bought an MTH HO ES44AC in CP colours for my growing fleet of motive power. I bought the ProtoSound 3.0 version, so that it would fit in with my other sound-equipped locomotives. Big mistake.
Much to my chagrin, there are certain "features" on the Protosound decoder that affect the locomotive's operation and are not able to be changed via DCC, if they can be changed at all. The speed tables and flashing ditch lights come to mind.
Regardless of the feature set, recently, the ProtoSound chip stopped working completely. I can't program or operate it. As I do not want to deal with the shortcomings of ProtoSound, I have elected to convert the unit to ESU LokSound DCC (knowing that voids the warranty). However, my problem lies in the LEDs used.Does anyone out there know the ratings of the LEDs used in these locomotives? I want to make sure I put the correct limiting resistor on.
Any help would be appreciated. Thanks!