PS1 : everything seems fine but no motor

Update: I've gone through 12 boards and they all behave the same.

I'm missing something easy. I've made 4 boards work over the last 2 weeks. What's changed? Any ideas? I removed the diode pack from the AC supply thinking that might be affecting it, but same thing.

Is"stuck in neutral" deselect what I'm describing? I didn't think it was since I can hear the sounds throttle up as I increase AC voltage, and I hear relays clicking. Am I missing an important ground somewhere?

I just can't accept that the first 4 boards I used (at random) were all good, then the next 12 are all deselected. The statistics say that really should not happen.

Are you using the same tender harness with all these boards? If you are there might be a bad motor wire.

There no harness. No it's a hack job, everything is directly wired. I've tested the motor with a DC power supply right at the ends of the wire that plug into the ports and it's fine.

Good thought though. 

Pictures and video if they help

Just one last bump to see if anyone else has any ideas. I guess I'm most interested in whether these symptoms are the "deselect" or not. I know these are on the list of chips that are susceptible, but I'm not sure that the behavior I'm seeing is consistent with a deselected chip.

If it is, then I need to buy a lottery ticket. by my calculations, the odds of doing what I did (randomly selected the only 4 good boards out of 16 total boards) are about one in 2000.

Jeff,

What transformer are you using?  When you start up you should set the transformer for about 11-12 VAC.

Bruce

It's a KW. I usually set it right around 11V at startup (measured with my fluke). 

 I can still put my good engines on the track and startup and run just fine. Maybe it's something to do with the board being outside the engine and bit grounded somehow? 

I run PS/1 boards on the bench all the time, that is not a reason they won't work. 

John, I am thinking the chips are NOT "deselected" because I can get all the sounds, the throttle audio works as expected (gets faster / louder with higher voltage), the reversing states and neutral all seem correct.  I thought deselected chips wouldn't respond to transformer input in any way shape or form.

Is there some way to trace the trace the DC voltage on the board backwards from the yellow and white jacks to find where the offending component might be?

Maybe voltage regulators (if there is one for the DC output, but maybe not since it's variable?  Not sure how they work).  I tried to check the flat voltage regulator nearest the diode bridge but my probe slipped, I shorted the middle and outside leg, and fried the regulator I think.  Had to move on to one of my other 11 boards.

Thank you guys for trying to help, I really do appreciate it.

Pretty hard for me to believe that multiple boards suddenly exhibit the exact same failure unless they've been abused somehow.

Is it practical to connect the GS4 chassis to the board of one of the 4 "working" engines?  And/or connect one of the 11 non-working board to one of the working engines?  This would be on the bench and might involve some jumper wires if the connector-ed wires aren't long enough.  This is simply the technique of seeing if the problem follows the board or the chassis.

BTW, I thought the PS1 motor connection is one from yellow, one from white.  In your photo it appears the motor is being driven from just the yellow connector (nothing connected to the white motor connector).  The two contacts on the yellow connector are the same voltage (used, for example, to connect to a twin-motor diesel).

OMG Stan I'm a moron

That's it!  Thanks for making me feel dumb!  I was assuming the individual pins on each connector generated a voltage difference, but it's one from yellow one from white.

Problem solved!

I KNEW it was something stupid I was doing!

Well, anyone who understands joint-probability calculations (1 in ~2000) is not dumb.   Feeling dumb is another matter! 

She's ALIVE!!!  Muahahaha...

Bit banged up, for sure.  She was never meant to run, she was only to be a donor engine to make her prettier sister serviceable.  But I managed to shove the soul of a Dash-8 into her mismatched Williams tender, and with some sparks and some bourbon, SHE LIVES!  Found out quick that her gearbox was pretty messy, looks like someone tried to lubricate it with a dead rat at one point.  So I spent a lot of time digging out hairballs from her gears and relubing her to make her slick again.

Also, she will have to live out her days faceless, as time and the harshness of this modern world have laid claim to her front boiler cover.  And there's a PS2 smoke unit in there, which, as I understand, operates off a totally different voltage from the PS1 so had to disconnect for the time being.  Found a 24VAC bulb to stick in her nose at least, so she's not entirely without personality.  Maybe someday I'll get around to 3D printing a "Don't Worry Be Happy" smiley face to give her some cover.

In the video (for those who aren't true believers) you can hear her working hard in the curves.  I'm guessing this is an 031 engine (I don't think MTH really ever intended anything to run 027) so her drive rods rub against the leading bogey in the turns causing that annoying buzz and drags hard.  

But the bottom line...SHE'S ALIVE!!!

Cool video. Glad you figured it out.