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Discussion Starter #1
I've seen several posts that were tantalizingly close to the subject on my mind, but none that actually answered my questions:
My first attempt at DCC was to install a Quantum Magnum into a “usa trains” GP 30. I followed the installation instructions (not much to follow) and ended up frying my light boards.
So far I’ve not received much help from QSI Solutions, so I’m hoping somebody out there in the real world of DCC can give me some advice…
1. Have you wired the FWD LT and REV LT outputs directly to your light boards without burning them up? If so, how??
  1. Do you know what the P3 (aux lighting) output is for? (No – apparently QSI is not building an auxiliary lighting board anytime in the foreseeable future) – and do you know what pin #2 (Data) does? Since I would love to have the cab lights respond to a Function from the Airwire 900 transmitter, is it possible that the P3 output could be used for that? If so, how? If I end up getting a separate, “function only” decoder to operate lighting, can anybody tell me how to hook it up through the Quantum Magnum – or directly to the GWire receiver?
I guess I should add that despite the problem, I love the new functionality of the loco with the Quantum installed - and will probably buy / install more of them. After repairing the light boards (burned resistor, blown LEDs, and burned-out bulbs) I built a little control board that senses polarity and sends reduced voltage to the lights. Works great, but I don't think that's what's supposed to happen.
 

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Discussion Starter #3
I have checked out Greg's website and searched for everything QSI related. Just now checked again for anything "resistor" related. You must be seeing something that I'm not seeing.
...also searched for "P3" to see if that question was answered. Nope.
 

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Hi, I actually got a copy of your email from Tony at Tony's trains asking for adivice and opinions.

So, the first thing I need to tell you is probably not what you want to hear: There are no "installation instructions" on a per loco basis on this decoder.

But, like ALL DCC decoders, it give you effectively FULL track voltage on the lighting "outputs".

So, whenever you put a decoder in a loco, you need to "set" the voltage to match what your lights want. In the loco in question, it appears that you did not check this, or you would have found out that they are 5 volts. So the application of 12 or 18 volts should have made them very bright for a very short time.

If you read my section on USAT F3 locos, you will see a LONG section on how I determined what voltages the stock lighting uses in this loco.

Unless you have documentation that tells you what voltage they are, you have to figure this out yourself, for ANY DCC or similar type decoder.

This gives you the information on what voltage is necessary.

Now you need to understand how to take say 12 volts and lower it to 5 volts, for example. On LEDs you calculate a dropping resistor. On incandescent bulbs, you can do this also, it's done a little differently.


This is still not enough for a USAT loco, since they also typically do funny stuff with reversing the voltage polarity to make lights go on and off directionally, or to change classification light colors.

To make it even more fun, USAT often uses a common ground for multiple lights, but in decoders, you need a common positive.


So bottom line, it's not simple when you are trying to use lights that are already wired together with commons and no documentation from the LOCOMOTIVE manufacturer on what voltages and currents are required.

This only addresses you question number 1.

Questions 2 and 3: no you cannot use this, it is for a piece of hardware that is not available yet, and it is not a universal output. Don't even consider it, you may destroy the QSI.

Question 4 is yes, we believe so, someone wants to do the same, we are waiting for someone to do it to see if it works.




Regards, Greg
 

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Discussion Starter #5
b]Thank you![ [/b]
Sure wish either QSI or "Throttle Up" (the business that created the wiring diagram that accompanies the shipment) would have mention this fact in the installation instructions.
Since I did not know whether the output was a constant voltage or not, I ended up using a zener diode arragement to pull the voltage down to 5 volts. If / when I install another I'll simply use a resistor to drop the voltage.
I'll be doing more research / experimentation on the "function only" decoder and let you know how it goes.
 

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The "electrical" documentation is not really oriented towards "do it yourself", there is a lot more documentation on programming, a manual with about 265 pages!

USAT locos are especially problematic since they often started out at one voltage, and were changed to another in later production runs. I have two GP38-2's that have completely different wiring for lighting.

When Tony comes out with the plug and play USAT boards, what you want to accomplish will be a 5 minute job.

You can see the prototypes on my site.

Regards, Greg
 

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I recently did the lighting on a USAT GP-38 and GP-9, the light boards will need some attention IMO. I hacked the boards, installed new LED's, resistors and additional wires. I now have complete control of the lighting boards via DCC. Common annode bi-color LED's were populated, however the proto-typical need for same is in question.

Greg,

I'm waiting for the new QSI USAT boards too... Are you suggesting the USAT board will have complete control of all lighting?
 

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I have 3 prototypes, and they light the headlight and backup light and cab lights and number boards. They also control the classification lights. (Some USAT have red/green, some white).

The big deal is that you do not have to change the wiring , you just unplug the stock connectors from the old board, and put in a new board.

The picture below shows what comes from QSI, it is a main board with a daughter board.

Notice all the connectors on the main board for lights (to accomodate all the different types of USAT wiring) You get a sheet that tells you which sockets to use, based on your model:



Regards, Greg
 

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Discussion Starter #9
I would love to see how you hacked the light boards (Michael). My solution gave me some control over the lighting via DCC: headlights and 'marker lights' know what direction the loco is going and change accordingly. However I have no DCC control over the cab lights whatsoever. Whenever I run the train at night I worry that the engineer won't be able to watch the track ahead because the cab is so bright.
 

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I'm pretty sure I still have the pictures of my hack job on the lighting boards, I’ll look.

Originally I replaced the marker/number board and cab incandescent’s with 12V units if memory serves me, my Engineer was much happier... The higher V bulbs driven by the onboard 5V regulator netted proto-typical lighting power IMO.

Most if not all DCC boards use a common-positive and switch negative. USAT boards are inverse to DCC requirements as Greg alluded to and you likely now realize. That said I removed the light boards and used a small LED flashlight to backlight the PCB to aid me in following the traces on the PCB's while simultaneously drawing out the schematic. After working through my chicken scratch schematic I cut several traces to isolate positive/neg of the headlights, marker, cab and classification bi-polar LED's. I had to reroute the common-positive and negative wire routes to accommodate each board/LED/lamp. All resistors were pulled and jumpered while new holes were drilled in the now common-positive route to accommodate a new resistor for each LED/Lamp. Lastly I added some new wires to the board to support the isolated lighting needs as required.
 

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Greg,

Tony told me about the new USAT boards recently, thanks for the info and picture. That daughter board is intriguing, the concept will lend itself easily to future applications!

The new QSI USAT offering will make things a bit simpler for USAT future installations, not to mention the increased current handling capabilities of the new board. I sure like what QSI did with the Plug-n-Play Magnum Aristocraft boards, talk about simplicity, all you need is a screwdriver.
 

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Will be the same for the USAT, a tiny bit more time, but still a screwdriver and unplug and plug...

Got 20 locos waiting for the new units.

Regards, Greg
 

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Below are a couple of pictures of the GP-38 boards, this was my first attempt at hacking boards, latter efforts were a little cleaner...






































 
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