Proto 2 ,3volt SD90 Problems No nothing.

I picked up an SD90 cheap unseen.Figuring make a dummy. Here the loco looks clean like new. Placed on track nothing,no lights no sound, nothing. Tried loosening truck connections nothing.For a challenge I figured try to repair. It is a 3 volt proto 2. What would be most economical way to repair? MTH parts,nos. Or ERR ?

Original Post

If it were me, I'd send the board to GGG for testing. Before that though, I'd take my meter and make sure power is at least getting to the board from the pick-ups. Check at the board with the black and red wires on the seven pin harness.

 I wouldn't try the board repair myself unless you are proficient at the tiny component level repairs.

" on Sour mash and cheap wine " ??

Why go back to DCC when I have DCS!

If it has 2 rail/ 3 rail switch test that too.  I can test circuit board out of engine.  But with no response and I assume means no amperage draw, the board may not be getting power at all.  G

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First thing I do is check my ammeter, if there is zero power draw, start looking at connections and the aforementioned 2-rail/3-rail switch.

I've had my old Fluke meter 25 years, still works.  I have finally upgraded it, but the old one still travels around in the toolbox I take to club events.  Buy decent tools, they'll last a lot longer.

SDBOB1 posted:

I picked up an SD90 cheap unseen.Figuring make a dummy. Here the loco looks clean like new. Placed on track nothing,no lights no sound, nothing. Tried loosening truck connections nothing.For a challenge I figured try to repair. It is a 3 volt proto 2. What would be most economical way to repair? MTH parts,nos. Or ERR ?

If the goal is to make an unpowered dummy (not a motorized slave), why not simply remove the motors so the truck wheels spin freely.   Or is that not what you mean by "dummy?"

Note that the "cheapest" HF meters do NOT have AC current-measuring capability.  But I suppose with the "free with coupon" HF meter you could measure if AC voltage (which the cheapest HF meter has) is making it to the 7-pin connector as Joe suggests.  If AC voltage is getting to the board-pair, but you do not hear the proverbial relay click-click when power is first applied to a PS2-3V board set, then you need to contact one the MTH gurus who have responded above and decide if a repair is economical.

 

 

Checked voltage as I found my old vom. Ok.After giving a close look tonight,how I missed it,the motor leads connection are burnt at board.Looks like yellow wires are completely burned off ,damaging board and male, and female connectors. I was wondering what cause this burning? I would like to fix unit as I have 1 UP dummy. This unit has the American flag. I haven't attempted this type of overhaul yet. Ideas, ball park cost?

Start by testing the motors with a DC power source, 3-5 volts is about right, they should run at that voltage.

I'd consider getting the board set in the hands of someone that can test and diagnose it.  If it wasn't the board, and it's just connectors, it can certainly be fixed.  There is also a replacement board set, the PS32 boards.

Pictures help a lot.

Look in motor vents, if the winding are dark black, motor burned out.  If you test with DC, MUST have motor connector removed from board.

If you want to send the PS-2 board to me I can bench test and repair.  If you need motors I also have them in stock.  G

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Virginia Train Collectors Member

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