K-Line Berkshire Headlight Replacement

Hi usually you can remove the headlike assembly from the boiler front the bulb or grain of wheat light would have 2 wires coming out of the headlight in the front boiler assembly. should be easy most likely 1 screw has to be removed or you have to take the front truck off to be removed to access the wires and 2 plug connectors!

C:\Andy\File Exports\Instruction Manuals\30ST18382I.PRN.pdf (mthtrains.com)

read page 15 of pdf file describes how to replace headlight in mth Berkshire engine!

Alan

Before replacing, is the tender light working?

K-Line engine with TMCC, no? 12-14v bulb. I use 2mm incandescents from  Miniatronics. Screw may be be just under the boiler front. You may have pull the shell to access the screw. I don’t have this engine so just a guess but you should be able to see it above the pilot.

Pete

@Chuck Sartor posted:

Before replacing, is the tender light working?

Yes, it's working fine.

@Norton posted:

K-Line engine with TMCC, no? 12-14v bulb. I use 2mm incandescents from  Miniatronics. Screw may be be just under the boiler front. You may have pull the shell to access the screw. I don’t have this engine so just a guess but you should be able to see it above the pilot.

Pete

Yes, it has TMCC.  But, as I said, I'm only running conventionally.

Everything has been operating 100% since I obtained the engine in 2011.  My only correction was probably long overdue lubrication.  It developed a squeak about 5 years later.  Lubing solved it.

As it so happens, I have the 2mm Miniatronics bulbs on hand, if they're indeed the correct replacement.

If it's compatible with the headlight circuit, I'd really rather try to work an LED into the casing.  (I should have mentioned that in my original posting.)

Thanks for the help, guys!

KD

Regardless if you run with TMCC or conventional it uses a 12-14 bulb. LED is fine but calculate the resistor for 12v plus add a capacitor across the leads to keep the triac on.

Pete

Some of the power systems, we use, can provide up to 21 volts AC.  We have had discussions about 18 volt lamps, or LED's. 

For conventional operation with a TMCC locomotive, use a 680 ohm (or higher value) resistor and a 1N4003 diode in series with the LED, I use 3mm flangeless amber LED's for steam.

OK on the tender light question. Sometimes some of the TMCC functions will scramble even in conventional mode due to track sparking like going through switches and derailments and the headlight function will turn off. But with the tender light working that doesn't seem to be the case. Likely the bulb like you stated.

GRJ...

Thanks!  Once the patient has been opened up, I'll probably fiddle with trying to do as you suggest.  It's hard to tell with my aging eyesight, but I believe the headlight casing has a 'reflector' detail, which may accommodate a small (2mm) incandescent bulb, but not sure about the LED size. 

Chuck...

Now that's interesting.  Maybe with the patient opened up I might try applying a low voltage directly to the headlight leads just to double check.  If there's still life to the bulb, I'm assuming I'd need to have someone with TMCC capability do a reset?  And, as simple as sparking or derailments might be in this neck of the hobby, it could become a nuisance issue??  We'll see.

Thanks, all, for the help.

KD

In conventional mode, the default is the headlight on with full wave track power out.  If the headlight output isn't working in conventional mode,it's most likely that either a wire is broken, the bulb is out, or the board has a bad triac.

Bingo, GRJ!!

Surgery going well.

Found: The bulb-harness-plug is a short little bugger.  It terminates at a tiny board mounted just behind the headlight, mounted to the pilot.  BOTH wires to the male connector mounted to that board are broken!!  I have no idea how it happened.   There should be no relative motion between the tiny board/connector and the harness to the mother board during operation.  Word of the day: Conundrum.

So, first step...  I connected variable DC to the bulb's female connector (two small pins inserted to connect to the clips).  Increased the voltage slowly...she lit gloriously!.  Just to confirm it wasn't an LED, I switched the polarity...she still lit.  Ergo: Bulb OK.  It was easier to access than I thought.  If the bulb ultimately fails, it will be easy to remove and work on.  So, I think I'll table the switch to LED for now.

Meanwhile, back at the broken (at the solder joint) connection to the male connector board...  I tried to trace the rest of the headlight harness (two black wires) back to its mother board.  Well, I think I now know why they put an easier-to-get-to connection at the pilot!  That harness to the mother board is buried.  I can't even trace it there's so much 'stuff' ...much of it painted as black as the wires themselves!...in the way.  And, I surmise that there's a connector at the other end, too!  Which means I've got to get those 2 tiny wires re-soldered to that connector in situ.  I've gently pulled on the exposed ends of the wires to get as much leeway (about 1") for this micro-surgical next step.   I'm going to try to fixture the board/connector to remain firm for the operation.  I'll need both hands...tweezers in one, iron in the other...to do the deed. 

I'll let you know how it goes later.  Too late for tonight.

Thanks, again, for the help, encouragement, and suggestions.  Been a good experience so far!

KD

Good Morning!!  Yes it is!!!

#4198 all back together.  Headlight functioning perfectly!...maybe even brighter than before?

The X-acto 'helping hands' with magnifier helped immensely.  The Optivisor...essential back in my HO/N days...has become a workshop essential 'tool' for the O jobs...like this project.  1/32" soldering tip did the job.  Good night's rest stifled 'the shakes' of age.

All's well.

I would've liked to have had some pictures to show the stages of the event.  Taking/downloading/posting pictures is wife's job...she's the 'geek' in the family.

I'll try to get a still or video later today to show the healed patient strutting her stuff.

Thanks, again, to all for the help and encouragement.

KD

We can picture the process in our minds.