Tortoise switch machine power supply problems

[dadret]

(I posted this on the layout forum but maybe it should have been here)  I have 16 Tortoise switch machines on my layout hooked up to one 12VDC, 500ma power supply using cross wired DPDT switches (Option 1 on the Tortoise manual).  Most of the time they all work fine but for some unknown reason every three or four months I burn up the power supply.  The power supply is dead and there is usually a noticable bulge in the side of the adapter,  I just replace it and everything works again but I'd like to know whats causing this even though I have found a cheap source for power supplies.  I think this usually happens after I have either added a tortoise or two or done some other work on them.  I can't find any wiring problems (bare wires, crossed wires, etc).  Any ideas?

[mmartian22]

i ve got 25 of them what i did was divide out the power supplies i have three power units one each powering 8 machines each . there's possiblies that you may have to many  machines attached to the tranny in which could be heating  it up a bit.

[dadret]

I'm going to switch to a 1000ma power supply and put it on a power strip so I can turn it off when not in use.  I buy my power supplies from Parts Express and they are fairly reasonable, although the cost just recently went up, but maybe all power supplies are not created equal.

[gandydancer19]

I just replace it and everything works again but I'd like to know whats causing this even though I have found a cheap source for power supplies.  I think this usually happens after I have either added a tortoise or two or done some other work on them.  I can't find any wiring problems (bare wires, crossed wires, etc).  Any ideas?

You are drawing too much current and the power supply is getting too hot and burning out. There is a remote chance that this could cause a fire. To be really safe, I would advise you to put a fuse in series with the out put of the power supply.  If you upgrade to a 1000ma supply (which is 1 amp), install a 3/4 amp fuse.  You should be able to get an in-line fuse holder at the same place where you get your power supplies.  If you used a 3/4 amp fuse, the fuse would blow before the power supply was at it's maximum rating.  If you used a 1 amp fuse, the power supply would reach it's maximum out put level and still get warm or hot.  Having a little reserve is a good thing.

[baron9]

 I too had the same problem with my power supplies overheating then my local hobby shop woner turned me on to the NCE Switch 8. What this did was eliminate all my DPST toggle switches and all you do is hook two wires from the Switch 8 to the tortoise machine. The tortoise machine gets its power from the track. No problems with overheating again. Just my 2cents.

[dadret]

I switched to a 1000Ma power supply and wired in a 3/4 amp fuse - so far so good but time will tell.

[jeffrey-wimberly]

As an added measure you could install a heavy duty toggle switch inline on the power supply's output line. This would cut off tyhe switch machines when their not in use and stop the constant drain on the power supply, which would make it last much longer.