Blinking lights 5v board locomotive

Here's a quick video, watch the headlight.

https://youtu.be/JQv4wE3H7Ro

Hi Jeff,

The headlight seems to be turning off and on at random intervals. It might be something as simple as a loose connection.

PS2 engines still used Grain Of Wheat (GOW) Bulbs so they do sometimes burn out. Maybe the filament is almost completely broken but randomly makes connection and works. Similar to Christmas lights that don't work but when dropped sometimes begin to work.

If I were you I would pop the boiler off and look for loose connections. If nothing is found, try a different bulb, maybe from the tender light or cab light if equip with one.

Other than that I can't think of anything else that will cause this issue, MTH is not like TMCC that flashes the headlight when signal is lost so its definitely either a bad bulb, loose connection or bad constant voltage board for the lights but I think you will notice similar flickering with all other lights if the constant voltage board is bad.

I am sure others, more technical than I will chime in with other suggestions.

Hope this helps!

Daniel . Thank you for your help, I appreciate your time.  The thing is, the marker lights flicker when this is happening as well  even though I have them off, so probably not the headlight bulb. 

pennsy484 posted:

Daniel . Thank you for your help, I appreciate your time.  The thing is, the marker lights flicker when this is happening as well  even though I have them off, so probably not the headlight bulb. 

Well you are correct, if all of the light are blinking then I would blame the constant voltage board. This is beyond me so hopefully GRJ or Barry can chime in for more help.

Good luck!

Engine appears to have an operating tender backup light in reverse as well as cab interior and firebox lights.  Since it seems to be repeatable, might be useful to note if these lights also turn on/off in sync.  Could help to isolate what seems to be a loose/intermittent wiring problem.

Could be mux board, broken solder joint under heat shrink at connectors.  Could be bad fan motor. Does it do this if smoke is off?  Could be motor noise interference requiring shortening motor leads if they feed mux and come back to motor.  All depends on model an how it is wired.  If all interior lights go off including smoke heat could be the PV diodes, but markers going off with it really means more of a MUX/ 5V noise issue.  G

Stan and G, thank you for for your help.

I just ran it in reverse  The reverse light on tender is not working at all.  I also turned on Lin, which turned on the marker lights (which I think is correct for this locomotive since there is no Lmk option, but while the markers came on fine, the interior light just flicks briefly and doesn't stay on. 

Yes, it turns out the cab light is flickering too, which I hadn't noticed before.  Is the MUX board in the tender? I have added a new tether by linking it to the original tender with a spare PS2 wireless drawbar. I electrical taped the back of the drawbar to prevent shorting.  Maybe this is a noise source? I will make sure the tether wires are not passing over that looks like antenna copper traces on top of the boards in tender.

Tender light is separate issue as it runs right off the PS-2 board in the tender.  There are 2 MUX boards.  The transmit board in the tender that takes the HL, INT light signals from the PS-2 board and multiplex it to the Receiver board in the engine.  That way one Signal wire through the drawbar to the engine can control the HL and INT light.  Normally the INT Light has the firebox too, so turning off INT light turns off firebox. 

Engine Markers are also unique in that they are powered off the 5V and pcb ground at the engine MUX.  So cycling HL or IL can turn them off and on.  You do not have a separate control.  The Tender Marker are off the PS-2 board and would directly respond to LMK.

You very well could have caused issues with the drawbar mod.  Try that first.  Especially if it was working before you did this.  G

GGG.  Thanks for all the info. 

I was experiencing problems with the tether originally.

Looking again in the tender I see now that I didn't need to do the drawbar jumper.  I misunderstood what I was seeing in there since the tender end of the tether had no outer insulation/sheath, and the wires were folded and intertwined with the battery wires and hiding the connector. I thought it was hardwired  Anyway  I was able to just remove the tether and replace it with the new one (using 90 degree end inside the tender) .

I have one place on the layout with a back to back 072 S curve, which it turns out causes a problem when I use the close coupling hole on the drawbar.  My thinking was that if the close drawbar position isn't too short and doesn't cause a derail then the tether should flex just the same regardless  but not so. I guess it's just too tight between engine and tender and it causes the tether to get pinched and pull out just a bit, just enough to case problems. 

Everything is working fine now. I will just use the longer coupler position (in fact if I recall MTH calls the closed coupling hole for display only anyway). I went through all connections to make sure well seated and looked but didn't find any knicked wires  and added some electrical tape along areas where the wires run along metal in the engine.

I really do appreciate all the very specific on point information you all share.  For me enjoyment of the hobby will mean being able to understand these electronics and being able to get in there and fix and tweak, especially based on the aging of the older command locomotives.  

Yep.  Glad you got it.  The OEM harness from the factory typically have that external harness with exposed wire no sheath at the straight end.  The Replacement from MTH is full covered, making it the choice for this mod.  This is also the issue with straight end being used.  The PV/Light signal, and motor leads at the other end are on the Outside pins of the tether. So if they pull at angle your going to loose one or the other.

If you are up for it, what you have to do is grind the tender shell exit hole for the tether, so that in curves the covered tether can move laterally in that hole to prevent pulling plug out of engine; or exerting too much side force.

Ultimately without doing that you still are straining the tether at the plug where the sheathed wires go into the rubber coated plug.  That is where the wires break internally, and you wind up loosing a function or two requiring a replacement tether.  G

GGG, thanks again for the information, the bit about which functions are on outsides of the tether is especially good to know. 

I don't plan to grind the opening of the tender, at least not yet.

Regarding "straining the tether at the plug where the sheathed wires go into the rubber coated plug.  That is where the wires break internally, and you wind up loosing a function or two requiring a replacement tether", I am thinking that very issue over and over in my head. It seems like the outside sheathing is actually not helpful for this problem.  I broke the seal of the outside sheathing and the plug which allows more easy flexing of the wires at the plug, of course with the eventual ramifications.  But I am wondering if removing more of the sheathing, all the way back to tender front, would actually be better by allowing the free wires to move all along their length between the engine and tender.  Thoughts on this?

I don't mind tethers, I just don't like the look of the 90 degree plug, even though it makes sense in operation.  Not worried about the look of the multiple wires, in fact I might prefer it 😁, see real decapod:

Just wanted to share an update on this.

The plug eventually got worked out again causing the headlight flicker.

As I mentioned above I am wondering if removing more of the sheathing, all the way back to tender front, would actually be better by allowing the free wires to move all along their length between the engine and tender.  So I removed the sheathing along about 2/3 of the tether, and made sure to have a large length of the unsheathed wires as slack just inside the tender to allow it to move in and out easily.

I suspect that the actual wire is not breaking anywhere but either the tether plug or the metal contact inside the plug for the end wires is coming loose, so I hot glued the wires into the plug (glued around the wires where they go into the plug, and down into that opening) and again hot glued the plug into the locomotive.  Also painted the hot glue and the wires with black gesso. 

I am able to run it with the close coupled hole on the drawbar and I like the look. If it lasts a decent amount of time without the headlight problem maybe I will just consider it a periodic maintenance job   If it fails soon, then I might hard wire it, and have the plug connect/disconnect inside the tender.  Or go back to the 90 degree angle tether.

Funny thing is that I don't mind the 90 degree on my other locomotives that have it, but now that I have run this decapod like this I don't want to go back.  🤣

Current configuration:

No problem, most folks just do not want to see multi color wires.  Many of the early 4 wire harness where like that, they just used all black soft flex wire.  G