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Me again, have a locosound board issue this time.  Got in a older Penn Turbine with locosound, doa.  Was able to order replacement board from MTH.  Installed it and powered up and horn blows no other control.  Now the "fly in the oinment".  The custmer had been into this unit before turning it over to us and am not sure just how far they took it apart.  I know the old board was toast has a blown coil/cap.  But what I'm not sure about, is if the little mylar insulator should be between the regulator and mount in the attached picture.  There wasn't one.

20180319_113207

Thanks.

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Last edited by Charly
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You need that insulator IF the circuit requires the metal tab of the regulator to be electrically isolated from the conducting metal heatsink/frame that it attaches to.  Not all circuit designs require this isolation.,

Here's a typical TO-220 (the package style of your regulator) heatsink assembly:

to-220 heatsink

From what I can tell in your photo, there is a white-colored Shoulder Washer (item 2) which keeps the metal screw (item 5) from touching the metal tab of the regulator.  That being the case, I'm thinking your board does require the isolation and hence you need the insulator sheet (item 1) between regulator and heatsink as illustrated above.

 

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Cheryl, Stan is correct.  Mica needed.  Anytime someone has been into a board before throwing it on you, carefully figure out what they did.  This is a tough one as you may have put in a new board and blown it following what he did before.  Not your fault.  Whenever someone has been inside a locomotive and you throw parts at it, you may end up being the owner of a bad board.  I will not waste my time trying to fix something that was messed with before it came to me.  I always ask if anyone had worked on it before.  I see this often and many people have got upset with me because I will pass working on a locomotive.  Many self proclaimed repair experts exist in our hobby that should not be touching anything.  We also have many great people that deserve help if they are honest and outline everything they did.    

I can see how this one got by the boards.  I hope you can work it out.  You do not deserve to be hurt by this from following something someone else did.

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