Large Scale Central

K27 Meltdown

Electronics Power and Sound
#1

For some unknown reason the circuit board in the tender of my K27 had a violent burn down. I was running on track power at the time and it just stopped, the Revo said ‘no link’. Opened up the top and smoke came pouring out. After I took the tender shell off this is what I found:

I have been in contact with Bachmann and they don’t seem to understand what I need, and the circuit board they show in the parts available file doesn’t look like the one that I need. I was wondering if anyone out there might have one available from a unit that they gutted. I believe that mine is an early version. Here is a pic of the complete board. I am more than willing to buy at a fair price.

Just to be clear, this is the board in the tender that the Revo plugs directly into.

I apologize in advance if this is not the correct place to post this.

Ron

#2

Ron

I have one you can have for the shipping.

PM me your address

Rodney

#3

Thanks Rodney,

PM sent.

Ron

#4

I have a big box of those and some newer units. However, I made absolutely certain, with strategically drilled holes, none of them would ever hurt another hobbyist.
This is graphic.
When folks can only do plug and pray, what happens when the plug requires prayer?
Cut and throw always works.
Next on the list would be the experience of doing it yourself, without some Ames Super Socket.
You’d know how to jumper the burned tracks.
With the tracks burned clear to the socket proper, one would guess the damage didn’t stop at the socket pin.
I would fathom a guess that the Revulsion is toast, also.

#5

Ron

The middle picture shows two wires connected to the center of the track/battery switch. What are these two wires? The track/battery switch is in the battery position. You said you were running track power. If you had the battery and track power connected somehow at the same time, that may be the problem. Especially if the track and battery were opposite polarity.
Tom

#6

Takes a fair amount of current to vaporize traces that large, A properly sized fuse or resettable circuit protector probably would have limited the damage. Good luck on your repairs !

#7

Looks a lot line the smaller board under the motor I toasted last year. Thanks to Terry, mine is back up again. I is assumed in my case the tender derailed and shorted sending massive power in places it was not supposed to go.

#8

Ron
What sound system is installed in this engine?
Is it the Revo with sound or something else?
If is another sound system, is the Revo a non-sound one?
Tom

#9

Tom

The two wires from the battery/track switch supply the power for the sound. When I first set it up it only had sound when in the track position. I did have the battery connected while running on track power. Have been running like this for the last 4 or 5 years with no issues at all. It is possible that the track power and battery power were opposite polarity, I have thought of that. The pilot truck derailed just before this happened and may have been part of the problem.

The Revo is a non sound unit, and the sound system is a Pheonix 8. The sound system still works fine, and surprisingly so does the Revo. Tried it in another unit.

Thank you to those with positive input.

Ron

#10

Ron
Thanks for the reply. I am interested as I don’t want the same problem with my K27. It looks to me like J1-7 (GND) may be connected to the large ground plane on the board. I can not tell from the pictures. Can you see if that is true? My K27 is not accessible at the moment. I would hope that GND is not connected to the chassis at some point. That would be bad. The trace from J1-1 was burned. The way the track/battery switch is set this shouldn’t have been connected. Please let me know if you figure out anything else.
Thanks
Tom

#11

Tom

Will let you know what I figure out.

Ron

#12

I wonder if the switch gave out or something/somehow made it bridge the gap? If you don’t get your board I’m pretty sure I still have one.

Terry

#13

Thanks Terry

Still not really sure what caused it. Rodney has committed to send me a board, but I’ll keep your offer in mind if it doesn’t work out.

Ron

#14

Ron

Interesting meltdown. Clearly a lot of current went down this path. Figuring out why or even how is likely useful.

When the battery/track switch is in the battery position there are no connections anywhere in the locomotive to either track unless added by the user. Thus unless additional connections have been added, a short on the track should have no effect whatsoever to these traces.

In looking at your photos there appear to be two additional wires soldered to the underside of the track battery switch and also there is a board with what looks like a whole mess of supercaps under the main board in the tender.

A wiring diagram of the components you added to your K27 might help us provide forensics.

Thanks

Stan