PS2 charging port voltage readings 3 engines ok 1 low at 1.29 vdc.

If you are using batteries, the port would read about 2.5 (the battery voltage).  If you removed the battery it should read 5VDC unloaded.

Normally if that low the processor cuts the audio amp output in half to conserve power for the processor.  Because your dragging down the 5V power supply running the board.

IF you charge the battery and plug back in does the voltage read 2.5 again?  Use one of the batteries that is reading normal from the other engine.  If it reads normal, except with the battery you charged, the battery is bad.  It may be dying and can't hold a sufficient charge after some time elapses.

IF even with a good battery the voltage reads low, either the Power Supply board has a defective component or 2.  The PS can be repaired.  Or the processor board is bad and shorting out the battery with the buck/boast circuit.  The test for this is swapping in a new Power Supply board.   The processor fault is not repairable.  G

When the battery has been fully-charged yet cannot play sounds for 5-6 seconds when track power is turned off, then that battery should be discarded.

That's the only test that counts.

This and a whole lot more is all in MTH’s “The DCS O Gauge Companion 2nd Edition", available for purchase as an eBook or a printed book at MTH's web store!

Barry, shouldn't it be charged first and retried before discharge.  It could just be dead, although with the use Willygee gives them that should not be the issue.

I am very surprised by the life of the 2.4-volt battery sets.  The batteries in the locos I upgraded when the upgrade kits first were released are still in use and still produce sounds for the 5-6 seconds.  That's about 10 years, I believe.

Robert,

shouldn't it be charged first and retried before discharge

I stated "fully-charged".

True.  You got me on this one, Barry.

Makes sense.  A 8.4V has 7 1.2V cells in series that are much smaller (much smaller than AAA) and have to maintain a 8.4V potential.

A 2.4V is only 2 in series using AA size.  Much more stored energy and only 2.4V to maintain.  Stated Life is about 7-8years,  but I had them in wireless phones over 10-12 years old before they could not hold for a phone call.  G

With the freshly charged pack shutdown sounds at 5 seconds.

Next question..what should be the voltage reading be at the port with battery installed  engine sitting on live track?

As stated in my original post.  About 2.5 to 2.7V depending on battery charge.  G

 Didn't see 2.7 volts in original post...but just took a reading after 15 mins of running and got a reading of 2.73 vdc on live track..comments very helpful.

 Next ?..if the battery went completely dead would this harm the board?

I have been running into a few of those batteries that are NG and will not hold the shut down sounds when fully charged.

Like Barry stated, that is the test that counts.  No shut down for me they are yanked and replaced.

It should not harm the board unless it fails in a shorted condition.  I'm not sure what that would do to the charging circuit, and I'm not that eager to find out.

Digi-Key Part Number283-2857-ND ..is this still a good supercap to use with ps2 3v battery substitution? I here ultra low ESR  is desireble.

NO you did not, but you saw about 2.5 the battery charge!  A recently charged battery is about 2.7V

Yes I think it can.  A shorted one definitely can, but a real weak one that drags down the 5V Regulator, forces the processor to lower the audio out.  When ever I hear the processor kick in to save itself I immediately shut it down and get a good battery.

You will know it when you have the volume up full, it starts up at full volume, but as soon as the start up sequence is completed the processor reduces volume to half.  If you measured the voltage at the terminal it would be below 2 to 2.2.  The lower the voltage the more the electronics are operating on a fringe.

I equate it to running a loaded car up a hill in fourth gear at slow speed.  Why make it lunge.  I know it is not completely the same, but I burn through power supply charging parts faster than audio amps now a days.  

I recently had a battery that did this.  It was an older one and could only hold a charge for a few shutdown sequences.  Before I charged it would force the processor to reduce volume.  After 2 charge sequences it could only play a few shutdown sequences before it would not complete them.  Why over work the charging system.

As Marty says, just toss it and get a new one.  The good news is these batteries seem to last longer than 7 years, and they do die gracefully.  G

 Would this be better? super cap from

Digi-Key Part Number283-2857-ND

That's fine, but you're paying almost double for the difference between 100mOhm and 110mOhm ESR, and you'll never see the difference in this application.

Digikey 589-1007-ND will works as well and is a lot cheaper.

i shall order 4

I would not order that one, I would use 1008.  The 2.5F capacitance is a better choice.  G

Both of the ones we're talking about are 1.5F.  I've used those in half a dozen engines, they work fine and always manage a full shutdown from power off.

Gentlemen,

   Just replace the battery with a BCR, if the engine does not work correctly then it needs repaired, send it to GGG or Guns to be fixed.  IMO most engine batteries are obsolete equipment.

PCRR/Dave

Dave, we're talking about supercaps to replace batteries.

Guns,

   What in the world is a super Cap?  Education please.  Any time you have an engineer like Bill (WillyGee) giving you the thumbs up you are doing something rights.

PCRR/Dave

  Digikey shows it at 2.5

No there not.  I tried them both, and in the end pay the extra for the 2.5F.  Some times there is not enough residual energy for full shutdown, though it is already 2.5V higher than the battery from a V potential perspective.  G

Bill & Guns,

   You are stalking about a super capacitor, I take it.  Little slow on the up take here.

PCRR/Dave

Not the part number you posted.

http://www.digikey.com/product...T.z_header=search_go

It is the number I posted.  1008 vice 1007.  589-1008.

OK, that's not bad, just a bit more expensive.  I'll buy that's probably a better choice.