I opened the base to fine tune it. I see 2 tuning posts. Is the one near the top towards the power input and db9 port the one to use? I know how to do it by holding down the horn button on a cab1 and leave it in the middle of the 2 extremes. I have done this before but see 2 tuning/volume pots. Not sure what these are technically called.
Thank you for your help.
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The "tuning" is basically as follows.
Note the position of L8 currently. With an engine on the tracks, slowly tune L8 in one direction while repeatedly blowing the horn. Stop when the engine stops responding to the horn signal. Slowly turn L8 in the opposite direction while repeatedly blowing the horn, and keep track of how many rev's (or partial rev's) of L8 you do. When the horn stops responding, turn L8 back half of the turns you just did from the other stop and you should be roughly centered in the proper signal band.
The L8 pot is marked on the board?
I’ve done this before and noted when the horn was the loudest and counted the rev’s in one direction with the horn going lower in volume while pressing the cab1 horn button. Turned it back to the loudest horn point.
Don't have one handy to look at, I don't recall having a big issue finding it.
GRJ,
Clearly marked L8 next to the pot.
Base is tuned now.
Thanks for your help,
Ted
Ted, that must have been how I found it. 
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