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 I have an older MTH PS/1 EMD F3 that operates intermittently ( pic attached).   After charging the BCR for three minutes and cycling the engine from neutral to forward,  the engine will rev up as is if it's moving but remain in a stationary position.   If I push down on the top board,  with my finger , and apply pressure the engine will move forward for as long as I hold it.   I have inspected the board in depth in all of the prongs are inserted into the bottom board  and I cannot find any loose wires that have become unsoldered.   The boards look intact as well.    I have applied pressure at various points on the top board and cannot find a specific spot that always fixes the problem other than applying pressure as a whole.   I have tried using wire ties to compress the two boards together but it isn't a sufficient amount of pressure  to make the engine work successfully every time.  

Also about one out of six times the engine will start up in an unusable error status.   When  this happens,  The engine will have the bell ring continuously until I turn the power off totally for a couple of seconds and then try again.   This error tends to happen if I apply to many volts between neutral and forward. 

 Not sure if these are indicators that the board is fried but any insight or help would be much appreciated.  The fact that manual pressure makes the locomotive work seems to indicate that the boards are OK, but I'm not sure.

Thanks much 

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Just a shot in the dark without seeing it, but one of the problems with the PS1 boards is that the voltage regulator is used to mount the board. Age, vibration, shock during transport can break the legs of the regulator internally.  Pushing on top of the board may be completing the connection in the regulator.  Likewise, a trace my be lifted or there is a poor solder connection on one of the relays.  I would inspect the solder connections on the relays, the pins connecting the top and bottom board and replace the regulator (they are available from Mouser electronics).

Thank you very much Jon.  That seems very logical.  In truth, I'm not sure which component on the board is the voltage regulator.  All the pins seem secure.  I separated the two boards and reattached the and pushed them in as firm as possible without breaking them but your idea of one of them having a broken soldier connection may be accurate.  I will pull them apart and reexamine them. 

Thanks again for for your response.

 

 

Usually when the loco starts up with the bell ringing continuously that indicates a short between the track and the board. If the horn blows continously there is a short between the board and ground circuit. If it were mine I would be brave enough to touch a hot pencil soldering iron to the connections that make the loco work with pressure, where they go through the board. Don't overheat it, just touch with a hot iron for a second or two. If you look closely you can see the solder soften after a second or two. If you don't feel comfortable doing this, you could send the chassis to me, I can try to redo the soldering and if it doesn't help I have the motion and sound boards on hand, if either is the problem. Email is in my profile. Good luck!

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