Piece of History - Need some tech assistance

What is your problem?  Not stated.  It can be easily fixed if DCRU is bad.  Any MTH instruction sheet for the early engines ending in -0 are non ProtoSound engines and use basic reverse unit with whistle or Horn board.  Switch is a lock out.  When closed contact reverse unit cycles.  When open contact the reverse unit locked in current state.  Fwd, Neut, or Rev.  G

Hi G,    My problem is the horn screeching continuously.  I removed one of the speaker wires using one of the small wire-nuts to disable it.  I'll attach a photo of that.  I have a pdf doc titled "DCRU and Original ProtoSound System", 29 pages in length and it goes into more detail about the ProtoSound engines and not much about the non ProtoSound models.  I just don't know how much it pertains to my model.  I've also attached a photo taken from this doc that shows a DCRU board.  I'll look today at my engine and take some more photos of the two boards.  When you say "switch is a lock out" - are you referring to the physical slide switch on my engine marked Reverse Unit lockout switch?  I've never operated this switch so I can't say what it actually does.  Is there a fix for my DCRU board or is the fix to replace it?  Is one available?   If you have any suggestions for me to try, I'd sure appreciate it.  Thanks for your help.     Bob

Your horn board is failing or you might have some DC offset on your track.

Again, you have the lowest end model of the control system at the time offering- DCRU (DC Reverse Unit) + Digital Horn board.

Bottom line- that horn board is long, long, long out of stock, and let's be honest, not super repairable. Your best bet is just removing the board completely. The horn board is not required for operation, and if failing- just call it out and remove it. No sense in leaving it powered where it could further fail.

If you are one that you just "gotta have a horn" folks, there are dozens of conventional add on sound boards out there that can be added- this is a plain Jane conventional engine, it's trivial to add one.

Williams True Blast series

ERR Railsounds

Heck, even an older Lionel Signalsounds board could be used for conventional operation of basic Horn and Bell.

In fact, the more I look at the picture, that may not even be the MTH digital horn board- that might be a Lionel or clone of one- of the warbler oscillator style horn board- known to screech as they die.

Let's face it, this is 25+ going on 30 year old electronics. It's done it's time.

At most, there are 4 wires on the sound board, 2 for speaker, 2 for power input, and again it's not needed for operation, not needed for the DCRU to operate- if failing, remove it completely is probably best rather than leaving it powered and cooking away.

Hi Vernon,   So the upper board is the sound board.  I'll pull it and not use it.  Does that mean the lower board controls the lighting in both the powered A and dummy A units?  I have a powered B unit and hopefully that will still function properly.  I can easily live without a horn but it would be nice to have one.  Going to a train show tomorrow to look for a legacy or lionchief plus 2 engine to dab my toes into command control.  Maybe someday convert this Alco to command as well.  Thanks for your help.  Bob

I have horn board and DCRUs.  But it would be best to have it tested to see which is the issue, if not a motor with short to ground causing dc offset.  It can be repaired if necessary.  G

Hi Vernon and G,   I'll see if there is anyone at the train show tomorrow (Feb 17) that can test the engine as you suggested.  Is there a way to contact me off line G so we can decide on how which parts I'll need?    Bob

My email is in my profile so you can email me.  Members can click to see it.  G