Mth premier 7653

It looks like it is 20-2006-0 (3 rail) CSX or 20-2006-2 (2 rail) CSX.  Good Luck!

I have the engine you are referring to that I bought brand new in 1993. It came with only an electronic reversing unit and a horn. It only runs in conventional mode. I have taken the shell off of other ones from this era and I am pretty sure all they have is 2 boards, the bottom board being the QSI reversing board and the top board being the sound board where the speaker in the fuel tank has a wire that runs to this board. There is also a small switch on the bottom of the chassis behind the front truck that allows you to lock the direction of the engine. See 2nd picture.  By default it comes up in neutral with no sound, then goes to forward when you cycle the powered and that is when the horn will work. The horn will also work while in neutral. There are no running sounds and no sound at power up time. Sounds like you got a modified unit.

I did read it was qsi sound upgradable which i think was done. Im guessing the reverse board is dead. I might try to put a wanted ad for a used replacement and see if the sound board works.

The engines will run (forward, neutral, reverse) without the sound boards but you have to have two jumpers on the bottom board. The sound boards just pull out of the bottom board. Unfortunately I can't find the diagram that shows where to put the jumpers, I will look some more. That would verify whether the bottom board is good or bad. Normally sound problems are "sound" board related because all the bottom board does is supply power to the sound board.

Here are two pictures of the bottom board only that are in the original Weaver E8 units which only came with reversing boards but no sound. If you look at the close up picture, the two jumpers are just to the right of the light blue cap (with dark blue cap behind the jumpers) along the edge of the board where there are 8 small plug in places.

If your bottom board looks similar, you try adding small jumpers using solid wire like maybe 18 or 20 gauge wire. I believe all early MTH and Weaver units used the same QSI bottom board.

Ill try those jumpers thanks!

whats the second board in the stack? It has the 9v battery plug on it. The top board is bigger and has the sound chip in it.

That would be a Protosound (PS1) upgrade board. Those boards are starting to have a track record of failing and/or getting scrambled and not working. The 9v battery plug is for the required battery for PS1 boards.

Some of the early PS1 boards required the battery to work, you might want to put a regular 9v battery in the holder as the next test to see what happens.