Skip to main content

6 replies

MTH Proto Sound 2.0 SD90MAC-HII Troubles

Stirling R. CallahanStirling R. CallahanOGR Forum Member

Need some advice on what to do with one of my locomotives. As seen in the attached photos, I have this MTH Premier Line SD90MAC-HII that I bough used a few months ago. It's a beautiful engine, which is part of the reason why I got it. That and it was a great deal! 

However, lately it's been acting odd. Sometimes when it starts up it will move without starting the sound and sometimes it will move and it will start sparking from the rear tuck inside the locomotive. 
Also, when I took it over to a friend's layout to try to run it on DCS for the first time, when it was put on the track and the power was turned on it immediately shorted the whole layout out, but when we ran it on a CW-80, as I had been running it at home, it ran but it was very sluggish (again as it was on my layout, however I think that may be because the unit is not powerful enough to pull that engine) 

I've also included a video that I posted on youtube showing the engine running and showing how sluggish it was, if that may be of help. 

https://www.youtube.com/watch?v=UbuPELFAyDc

I need some advice on what to do. I really like this large locomotive, but I want to be able to run it....I have two other NS units I want to run with it, but it isn't worth anything to me doing nothing.

 

NOTE: THIS IS NOT MINT TO SPARK A LIONEL VS. MTH WAR!!! 

 

10616212_10203756672548505_2310470141380504156_n

Attachments

Hide
Images (3)
  • 10616212_10203756672548505_2310470141380504156_n
  • 11133788_10203964112414372_660685069156280466_n
  • 11156116_10204085857497923_4273793488400812722_n
Original Post

Replies sorted oldest to newest

Marty FitzhenryMarty FitzhenryOGR Forum Member MEMORIALIZED MEMBER

I see your engine is 20-2628-1 a 2/3 rail locomotive.  Remove the cab and take note of your switches 2 rail-3 rail  and looked for burned wires on the bottom of any  switch.  These are DPDT slide switches.  I have run into this several times.  If that is not your issue, please read below.

 

Open your engine up and on the side of the PS2 board you will see a 7 pin connector.  Pull the plug off the board.  This connector brings hot (roller) and ground in from each truck and the rest (3 wires) of the wires go to your tach reader.  Next set your meter to continuity and on the truck that sparks hit the roller with one probe and ground with the other.  If you get continuity your issue is where the wires (black and red) connect to the truck.  The red wire is finding ground somehow.  If you get no continuity, do the same test with the other truck.  You will find the problem.  

 

If you do not get continuity on either truck, look for continuity between the red (roller) wire to chassis ground.  Work with these and you will narrow it down and find your issue.

 

 

Last edited by Marty Fitzhenry
Stirling R. CallahanStirling R. CallahanOGR Forum Member
Okay great! That sounds exactly like what is happening. I'll give it a shot.
 
Originally Posted by Jon G:

The red wire from the pickup is likely shorting to the frame.  With the shell removed, there should be clearance between the heat shrink tubing on the red pickup wire and the frame.  If not, either bend the wire on the eyelet or spin it around so it is centered in the frame slot.  I see this problem quite often.

 

Marty FitzhenryMarty FitzhenryOGR Forum Member MEMORIALIZED MEMBER

 

Your continuity meter will tell you what is touching.  Remember to pull the 7 pin plug off the board.  Check with your meter on everything you do and if you rely on powering the engine up to check you may not get lucky if a short exists.   A few extra steps are cheaper than a bad board.  Always keep the board out of the mix when chasing chassis shorts.  

 

If you end up re positioning the roller eyelet, be sure the swing of the truck is free without the red wire contacting the frame.

 

 

  If you get continuity your issue is where the wires (black and red) connect to the truck.  The red wire is finding ground somehow.  If you get no continuity, do the same test with the other truck.  You will find the problem.  

G GGGOGR Forum Member

The fact that it moves on its own is telling me you "MAY" also have the white motor lead wire shorting to chassis ground.  When the PS-2 engine is started the Yellow wire to the motors have Positive DC voltage available.  It the white is shorted a path is created that crosses DC with AC causing motion and sparks.  Certainly this can short a CW-80 with less amps available,

 

Or, as stated a red pickup roller is shorting and causing the direction change signal to start the motion.  

 

I would also inspect any are where the motor leads run near or touch the chassis, brackets, motor can.  G

Last edited by GGG

Add Reply

Views: 260
Post

Membership Required

We're sorry. You must be signed in to continue. Sign In or Register
×
Are you sure you want to remove from your Block List?
×
Loading...
×
When you block a person, they can no longer invite you to a private message or post to your profile wall. Replies and comments they make will be collapsed/hidden by default. Finally, you'll never receive email notifications about content they create or likes they designate for your content.
Note: if you proceed, you will no longer be following .
×
Link copied to your clipboard.
×

Access to this requires an OGR Forum Supporting Membership

OGR Forum Supporting Membership

Help support this forum with an OGR Forum Supporting Membership.
You will be able to watch the videos in the INSTRUCTIONAL VIDEO FORUM!
A one-year OGR Forum Supporting Membership is only $12 per year, so sign up now!


    OR     


Access the ALL the OGR VIDEO FORUMS AND  over 300 back issues of OGR
with a DIGITAL SUBSCRIPTION!



$12.00 per 12 Months (plus tax if applicable)
×