MTH ProtoSounds 1 Engine Moves One Direction Only

Well, since it cycles to neutral, it's probably not locked in a direction.  My guess is the reverse relay or more likely, the transistor that drives the relay.  It's not hard to replace the driver transistor, that would be my first thought.

And, thus- the common failure points of the lower PS1 boards.

https://ogrforum.com/...d-component-failures

Thanks gentlemen!

I'll start with the transistor and see if that's the issue.

It appears that the 2N5087 transistor is no longer available.

There appear to be a number of equivalent transistors available.

I have no electronics background and seeing supposedly equivalent components, but with different values on their spec sheets, gives me pause...

Do you know of a good substitute for the 2N5087?

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There are multiple electronics suppliers- basic google of 2N5087 found Mouser had them

https://www.mouser.com/Product...aNq3qDwaAnelEALw_wcB

Thanks, apparently I didn't Google hard enough.

The first few suppliers that appeared in my search showed zero inventory.

Forward transistor is at the edge of the board, reverse is near center.

Super! Thanks for that.

I was going to replace them both since I had no idea which one.

Again, searching at a supplier for the part number

https://www.mouser.com/c/semic...2N5087&instock=y

Similar search at Digikey https://www.digikey.com/en/pro...X4KSlwB2ZADABwDsV1QA