K Line F7 K25102 Horn Question

@Michael Cimba 040217 posted:

I just purchased a new unopened Baltimore and Ohio K Line F7 AB conventional set (K25102).  It says it has a horn but I can't get it to work.  When I press the whistle button on my Z4000 it cuts the power to the engine as long as I'm pressing the button and if I hold it long enough it cycles the eunit like the direction button, but does not produce any sound.  Wondering if this set in fact has a horn and if so, how to get it to work.  Thanks.

Michael

It should work just like any other horn is expected to with a DC offset- AKA whistle/Horn button on a transformer.

however, your statement of the engine losing power and given long enough, switching direction appears to imply the horn unit specifically is shorting when activated. Otherwise, the symptoms indicate something very weird happening with your Z4000

I know this picture is from a K-line S2, but the basic diesel horn board was a common part used. The horn board is the one nearer the bottom with the small flat aluminum plate is the heatshink. Again, I've been told that they (the K-line horn board) can fail, and this certainly sounds like a symptom of that happening in your loco. I've not spent a lot of time with them(K-line horn boards) but know the board design and chips used are semi related to many of the horn board designs of that time era- example Williams and even found that Aristo-Craft used the same sound recording chip. Again, I had one of these as a takeout from an FM-Trainmaster, so I do know exactly what the board looks like and what chips were used in the design. But Like I also said, I was warned by another local person with more experience who sells and refurbishes K-line engines that they had seen failures of those horn boards.

Picture came from this thread , user @GG14449 https://ogrforum.com/...0#158111058506897640

In theory, you may be able to unplug the horn board from the power wiring of the engine. It's just 2 wires. If then the engine acts normally and does not short and change directions when you press the Z4000 horn button- there is your answer- a bad horn board.

Engine details here http://www.legacykline.com/ord...mp;p_oem_sku=K-25102

I finally got around to taking this apart.  Please see the previous posts for the issue. This is the B-Unit.  It has a speaker but only one main board.  Trying to determine what component makes the horn sound.  There is continuity between the speaker wires and the speaker.  Nothing looks burnt on either side of the board.  Would there be a sound board in the A-Unit?  Would anybody have a schematic for this set?  Any help is appreciated.  Thanks!

Michael