Strange issue with PS2 Loco

Try changing out the battery to see if it goes away.  G

PS2 batteries typically need to be replaced every 6-7 years.  Page 16(in most owners manuals) describes how to test the battery to see if it needs to be replaced.  

If by "long term effects"; you're asking if it will harm anything; the answer is no.  The long term effect is that you can expect to need to give the battery some charge after sitting idle for an extended period.  

The BCR proponents will  tell you to replace those  batteries with a BCR2(a capacitor) and forget about battery issues.  That's probably a reasonable course of action for folks that let their engines sit for extended periods, if cost is not an issue(BCR2 costs more twice that of a battery). 

2.4V batteries last far longer than the 8.4 V batteries.  So BCR are not as economical for the PS-2 3V systems.  G

Actually the battery hold a charge fine for about a month, so I don’t think it’s the battery.

There is something odd about the built in charging circuit, it is as though when the battery is being charged, power is somehow diverted from the amplifier. I have never noticed this with the other PS2 engines, they all seem to charge and output sound just fine even with a low battery.

I had a SD-70 do something strange, sound wise, not long ago.

At start up, the sound volume was very low.  Then at about the end of the start up sequence, the sound would come up to the normal volume. 

The engine was a couple years old and had never had the shell off.  I removed the shell and found that the battery harness had a loose wire connection(inside the plastic connector). 

Fixed the wires(by removing the offending plastic connector) and everything returned to normal.