My recent PS2 5V board failure

all those ps 2 5 volt boards are unrepairable and cannot not be taken apart successfully! believe someone that has tried, not worth the effort! you can buy a used ps 3 volt board if you can find one  and replace the board and it will work again !only thing is you would also have  to replace the 16 ohm 50mm speaker with a 4 ohm 50 mm speaker and install a 2.4 volt rechargeable battery from an asc tech or mth in Maryland! also u could have n asc tech install a ps 3/2 board and all features will work as before but not cheap the board alone sells only to asc tech and sells for around $300.00 or less! I just finished a l3 mohawk for a client and he love in no more battery to deal with on ps 3/2 board uses a super cap instead!

ps. I would bet if you use a ohm meter and test center roller of engine to metal case you'll find a short. ps 2 5 volt board fail quite often due to there age ! the win cap you pointed out is a very common failure sometimes they explode!

!!!

Thanks, Alan!  My first check was just that; my trusty voltmeter showed roller to ground continuity. 

I am still curious about the root cause.  Did the capacitor overheat and melt the two wires, or did the wires overheat from an amp draw that melted their insulation to short into the cap? 

The board was a bad one (PS2-5) because the caps were N.G.  As alan said, you can't repair them!

    Steam Forever

           John

It's pure speculation on the root cause, it's hard to know if the cap blows and takes something else out, or the diodes inside croak and kill the cap.

I will say, I'll bet the brand name on that cooked cap is WINCAP, I see lots of those popping.  I have had limited success (very limited) in replacing that 330uf 35V cap and reviving these boards.  I've gotten a couple of them back, obviously suggesting the cap was the only failure.  I've also had a couple that the cap was bulged and leaking, but the board was still running.  Needless to say, I replaced the cap on the spot, and for at least two of these, that's solved the problem for several years.

Thanks, John!

For replacing the capacitor, were you able to snip it out as the boards sit, or do you have a magic way to separate the PS2 boards?

you just crush the capacitor just above where the leads go threw the pc board not to pull to hard or you'll rip the leads out of the circuit board. Usually needle nose plier and crush the bottom of the capacitor but not the leads and remove piece by piece then solder to leads on the capacitor and mount  where ever it will fit. if your not good at these kind of things I would not try to! 

Thanks, Alan! 

It while be worth a try!  Anyone have a recommendation on the best cap to buy for the replacement?

You can get the cap from anywhere, Digikey is a good source.

https://www.digikey.com/produc...89-3752-1-ND/6599213

Thanks, John!

I ended up going the "get-it-now" route, and these will be here at my house sometime today:

https://www.amazon.com/330uF-1...ndustrial&sr=1-5

I will give an update on how I fare with this salvage project.  Best case, I get the switcher running again; worst case, I have enough replacement caps to proactively swap out all of the Wincaps in my extensive PS2-5V fleet before powering any more of those engines up!

Hard to tell if that is the right diameter and lead spacing, but you'll know later today.

Good points, John!

10 x 13 looked about right, though I didn’t measure the old one yet. 

From the photo, the cap looks ok. Only thing that would melt wires is a short to the metal frame with. Hiigh I draw. I would first find the Nick in the wire insulation and shrink tube over it. I had this happen on Lionel's M7 and MTH SD35 CNJ. Both cases the wheel flange cut into the hot wire on curves. Caps do go bad and puff out at the top. Also, you man notice the yellow chemical on the bottom rubber where the leads are.

Here is my pic (previous pic was from a similar forum post):

It is tough to make out, but the red wire and black wire were melted to the cap and charred from shorting.  I cleaned them up and put a small piece of 3M electric tape on them.  No other wires, even to rollers, are bare.

The cap is only slightly puffed, but I’m pretty sure it is shot.  I removed the battery and checked the cap for voltage, so going to crush it now.  Update coming.  

Well, the 330 cap is out of the way, but one of the three 220 caps is also puffed.  I should have ordered some of them when I bought the 330s.  Assuming I shouldn’t install a 330 cap in its place, right?

Both caps out of the way:

New, rechargeable batteries and a lot of new 330 caps have arrived.  Cap diameter of 10mm matches the original; 13mm cap length is a little shorter.  Lead spacing looks identical. 

I’m not the neatest with the soldering, but I got a new cap in there and it is secure.   220 35s will be here tomorrow.  

Tony, I appreciate you chronicling this.

Thanks, MikeH! 

I'm hoping that I get lucky in reviving the switcher, but if not, it has been an interesting exercise!

Well, I hope my terrible soldering skills haven’t made things worse, but both new capacitors are in place:

After dinner, I will do some voltmeter checks, add a new 9v battery, and slowly apply some AC voltage to the engine...fingers crossed!

9v battery hooked up, and no wires or components letting out any smoke:

👎

Failed.  

Slowly added 12VAC to the track, and amps went up to 3.0 with no signs of life, so I stopped.   

I will look at the boards and wiring a little closer for anything obvious, but I believe the switcher is headed to spare parts duty.  

I have never under stood why  MTH does put some kind of protection for these board?Is there some kind less expensive route to go?Or alternative replacement?

I probably paid $250 or so a long time ago for the switcher new.   Mileage was pretty low, but chrono might have been up there, as it mostly sat on a powered siding. 

I think replacing boards and speaker to PS3 is about $270ish...better off to buy a new one, if I needed to replace it. 

My biggest worry is the maybe 20+ other PS2 units I have, that each have little run time and may suffer the same fate. 

Excellent point about checking the 5v regulator!  I had to pack things up for the evening, but I will try that tomorrow.  

I can see no other chars on any wires or the boards (can’t see all of the inner parts of the boards), but is there anything else you can think of that I can check tomorrow?

So long as you put the correct batteries in the rest and keep them charged you should still be able to get some more mileage out of them.  The switcher could still run in conventional with a simple e unit board.  At least you gave it a shot. 

My question is where is that 36 Watts going?  Pull all the connectors (including battery) from the board-set except for the 7-pin power connector on the power-supply board.  Presumably you're still drawing short-circuit-like currents.

36 Watts will heat up a component in a matter of seconds!  So carefully touch/feel around the board.  36 Watts in a concentrated space like a component is effectively the tip of a soldering-iron!    If the heat is coming from one of the bigger multi-pin chips on the larger board then that's bad news as the chip is likely cooked and those chips are irreplaceable.  But if it's a component on the smaller power supply board that's shorting and preventing 5V from reaching the larger board then there's a sliver of hope for a resurrection.

Excellent!  Thank you for the tips!

My experience has been that the apparent flaw is between the two boards in the stack.  Since they're about 99.9% impossible to separate to get to most of those components, that usually renders the board set toast.  Years ago I separated one of these in a very long session and replaced some diodes and the caps.  It actually did revive the board, but the amount of time it took to get them apart makes that option prohibitive, at least in my book.