I am waiting for a Big Boy decoder and pc board from an Athearn Big Boy and want to get a schematic of where all the connections go to. Does anyone know where I might find this. I tried the Athearn website and got the manual but it doesn’t show any schematics or other helpful data in my specific needs. Any suggestions? I can trace some of the solder pads to some areas but not all of them.
thanks,
-Bob
PS: I know how much everyone likes MRC stuff so please don’t comment on that. This is just and experiment in putting sound into a large steamer I have.
Where did you even find a manual on the Athearn site? I looked and couldn’t find any. That aside, are you looking for a schematic of the decoder, or really looking for a connection diagram? And do you know what the MRC decoder model number is? If you know the model number, maybe you can try the MRC website to see if it is listed there. If it is and the description says “resources available”, generally that means the decoder manual can be found and there should be a picture or sketch of the board with the connection points identified.
No manufacturer that I know of actually provides a schematic of the innards of their decoders. The closest you might come is to find a wiring diagram showing where wires actually connect to the decoder, but you’re on your own to figure out which wire is which if they are not color coded.
There are NMRA standard color codings for decoder harnesses, but not for the actual wire used by various manufacturers within their models.
MRC, especially, seems to be very secretive about their products.
i should have made my request more specific; I apologize if I wasn’t very clear. I need the connection diagram so I can wire it to my loco. The decoder is part of a large pc board that fits inside the tender and another board that goes in the loco for track, motor and headlight connections. I have a photo that was on the listing for this item (haven’t recieved it yet!) and I am hoping i can track some of the connections on the pc board. I expect some connections won’t be as obvious, thus the need for a schematic of the connection points and not of the actual decoder/pc board circuitry.
Right now this is just a WAG but if coming from Athearn, I would expect instructions with both boards. The light board decoders I have worked with have obvious labels on them. The decoder boards, not MRC brand, I have bought came with instructions.
Even the Bachmann PC boards for motor, lights had labels on them.
I have some lousy photos of wire colours I took as I stripped the lower board from my challenger. They might help but I don’t know how to put them up on the thread. Did’nt go into tender shell so hav’nt a clue , till I have a look in side that is, if you can wait a couple of days I’ll have time. Be back on in 24hrs.
Well, it is still not clear to me what we’re looking at. Is that a picture of what is cuurrently installed, what the new decoder looks like, or…?
Anyhow, I found a link that describes replacing the BigBoy MRC decoder with a Tsunami, which might be relevant to you because it describes the connection points on the MRC decoder. It also states that the underside is labeled to indicate the functions. But what they are removing does not look like anything in your picture. But here it is anyway in case it might be helpful: http://www.dccwiki.com/Athearn_Genesis_With_Tsunami_TSU-1000
OK, now this is beginning to make sense. Next time include ALL the info in your first post.
Get your multimeter out and use the resistance scale to do a continuity check with the original loco. Match the color wires to draw out a diagram of how the original install was. Left rail, right rail pickup, loco and tender. Lights may be a little difficult if LED’s as there is a positive and negative lead. Light bulbs, no polarity issues. I suspect no polarity issue with the two speaker leads. Also consider motor leads. I want to assume Athearn follows NMRA for wire colors but that is a guess as I know Bachmann does not.
Just to make sure we all understand what I have: I purchased this decoder and PC on line and don’t have it yet. I don’t have an Athearn Big Boy but planned to use this in my Rivarossi Challenger, if possible, which I think I can. All I wanted to find is how to identify all the solder connections on the decoder/PC board so I can wire it to my engine. I will have to add a speaker as well. Since I don’t have an Athearn Big Boy I can’t check anything on the original install. Once I have this in my hands I can determine what connections I will need to identify, which is why I wanted a schematic of the connections. As soon as I get these parts I will post my findings and hopefully obtain the info I need. I really appreciate all your comments and help so far. Again, I apologize for any misunderstanding.
Sorry I meant to thank you for that link, it does look like it may have a lot if not all of what I may need. won’t know until I have the unit in my hands.
Right, so the Tsunami’s going in a Riv Challenger, think on, have you checked it’s motor ampager. If it’s an early one it could be more than the Tsunami’s 1amp max. My Riv Blue Goose’ll need re-motoring with a can when I get round to it, that was well over when I checked, just a thought. It’s the 6 way mini connector thats driving me nuts.
I don’t have a Tsunami decoder. The decoder shown in the photo is an MRC removed from an Athearn Big Boy. I purchased the decoder on ebay and I don’t have an Athearn Big Boy. I plan to install the MRC decoder in my Rivarossi Challenger, which is a later model with can motor and flywheels. I still don’t have the MRC decoder and PC board yet, should be here tomorrow or Wednesday. When I get the decoder and have a chance to look it over, I hope to know just what info I will need.
Ah, beginning to see the light, I’ll take the shell off mine and have a butchers. You say you ain’t got your’se yet, good cos our show’s on this weekend (lydcc.org.uk) an I’m up to me neck in it, might be after that, as I’ve to dig it out from under the layout in the cellar.(basement) It’s one of the jobs that fell off the back burner so to spaek and I need to find it. So no sweat , I hope.
As I said earlier, could someone let me have details of how to put photo up.
Well, i finally got the MRC decoder and pc board for the loco. I took some closeup pics and posted them below. I can see now that the connections are labeled although not quite as clear as they could be. I am referring to the six holes at the end iof the decoder board where it looks like a connector mounted on the end and made contact with the holes. It looks like the outer most are for the track power pick up. The next two, moving inward, (?) are for the motor, one grey and one orange. The LED is marked but has some solder points where the wire was cut; I am assuming this was for the headlight on the loco. What is not clear is wether the second set is for the motor or could it be the third set? The label looks like it is between the 2nd and 3rd holes? I can try a test setup with a spare can motor. Any suggestions or comments before I charge into this? This is why I wanted to get a diagram of the connectons to the decoder board. I don’t want to burn it up by making the wrong connections.
The third photo is at the back end where the LED for the backup light is mounted, but it shows the white plug for the speaker, so that is clearly identified (will have to cut the plastic away to solder some wires and a micro connector for the speaker).
Using first picture, counting down from top, my guess from looking at it: first hole is track pickup, second is the motor, third hole is LED - (and it seems to be VERY nonstandard - the - connection on decoders is generally one of the function wires - in this case that looks liek the overall circuit ground for the deocder - that big expanse of copper, and dead int he middle are the wires from that big capacitor, and the minus side of the cap is in that big expanse). Up fromt eh bottoms, same thign in reverse order: bottom is the track pickup, second from bottom is motor, third is LED+. Sicne the motor leads aren;t labeled for + or -, if it runs backwards when in forward you’ll have to either swap the wires or set CV29 to reverse direction.
And wow the sloppy patch job on the top where those little jumpers are soldered between the diodes and what I suspect are the motor drivers. Top one bridges 2 pins, bottom one bridges 3. Odd.
If I were guessing I’d say those wire are supposed to go to the Leds. The top view makes it appear that those are solder point pads, and when you turn the board over the labels say LED - and LED + to correspond to what is on the top.
If you look at the board where the three top and three bottom holes are grouped together, are all three holes in each group connected to each other via the trace on the board?
And what is that wire for that looks like it is hanging out the other end of the board?
Looks like there is a trace from where the wire is soldered to that innermost hole. On the component side where the wires are soldered I see L+ and L- markings - for whatever reason the diplicated the connections. The three hole groups are patterned like they could connect to a plug/socket arrangment, like the 2 pin one for the speaker, but it seems this was bypassed. As for the speaker, you cna get the other half of those connectors fairly easily, might be better than trying to unsolder that one and damaging the board.
