Lionel SD90MAC Speaker Humming

If there are two speakers in the fuel tank, there was a problem a long while ago where the speakers are out of phase.  It was corrected by reversing the wires on ONE speaker.

Think this is it.  Others may remember it.

Fred

Actually, the crossed wiring issue between the two speakers in the fuel tank was with the original scale SD90MACs issued in 2001. This concerned reduce volume output if the speakers were out of phase.

These are later Lionmaster units if I read correctly. A humming is more likely to be coming from the Railsounds amplifier board.

If the hum is at a frequency of 60Hz or 120Hz this is usually a result of a defect in the powersupply and can be traced to the power board or the amplifier board. Try swaping the power board between engines, the board with the large silver shield on it. If the symptoms change or move then the problem is with the power board. If they stay the same then the trouble is with the audio board.

It should be noted that as with any electronic circuit board all power should be turned off and all batteries disconnected. Give the item a few minutes to completely discharge before attempting to do anything. Ground yourself when touching the boards. If you do not have a rist strap for this then grab ahold of something grounded and keep touching it when touching the board. Static, even the kind you do not feel, will kill the electronics on these boards! When pluging the boards back in make sure that they are pluged in properly, YOU GET ONLY ONE CHANCE! "Do or do not, there is no try."

Al

Thanks guys. I think if it is an electronics issue I will bring it in to my LHS for some professional help. I don't want to wreck it as the overall sound is still fine.

Jay in Ottawa