New super cap install for the 3v causing major overhearing issues

I suspect you wired the positive to the wrong side, that's the only thing I can imagine that would cause this issue.

New super cap install for the 3v causing major overhearing issues

???

Try not to listen? 

GR J, See pic...

neg & POS are correct...

Are you sure the + really goes all the way to the board properly?

If the connections are correct, I can only imagine either the cap was defective or the charging circuit provided more than 5V to it.  Supercaps are VERY touchy about over voltage.

It worked as it should when powering off/ down.  If the positive wasn't connected wouldn't it not hold its memory when powering down the transformer to communicate ?

Actually, depending on the exact chemistry used in an electrolytic capacitor, some will function for a short time at reverse polarity.  I had some boards manufactured where they reversed the capacitors, they all functioned during preliminary bench tests, but the capacitors started exploding after operating for several hours, quite a surprise!

So what do you recommend.

I have another SC. Should I try it or just replace the battery in this one. I really don't want to damage the board. It is a custom subway power unit shell.

Well, the safe option is the battery, they should work fine.  I have no idea why that cap went, but I confess that I'd probably be a bit reluctant to do it again.

I would point out one fact here. 

subwayrunner posted:

Hi, after install I ran it for over an hour when I started to smell something in the room.

It ended up being the install I just did. It was super hot and stunk bad of a burning motors..

Took it apart & the motors were sizzling...

I can't imagine how the cap dying overheated the motors, so I'd have to look into that further.  Perhaps the cap going up was just a symptom of a larger problem.  After sticking dozens of these in locomotives with no issues, it's hard for me to believe that the cap caused the symptoms you see.

gunrunnerjohn posted:

...

I can't imagine how the cap dying overheated the motors, so I'd have to look into that further.  Perhaps the cap going up was just a symptom of a larger problem.

But if I understand it, the cap did not get hot (?) and/or fail...it's just both motors that are sizzling.  He says it worked as it should when powering down (presumably playing shutdown sounds, saving memory, etc.).

I too am baffled on how the supercap affects motor overheating. 

My first thought was when the modification was made, some mechanical obstruction was left in a motor gearbox or whatever thereby causing the motor to overheat.  But apparently the overheating is on BOTH motors so it's hard to believe this would happen on both motorized-trucks.

Do you have a method to monitor current (Amps) going into the engine?  If so, measurements of the power required to run the motors at idle, then 10 sMPH, 20 sMPH, etc. can be revealing.

'

Stan, I was keying on the wrinkled heatshrink on the end, but you may well be right.  If that's the case, then the cap probably had nothing to do with this failure.  I think I'd simply unplug the motors and try running them on a bench supply to see what they draw.  If the unit is actually running, I'm a bit mystified exactly what is happening or how it could have resulted from the cap installation.

Yeah idk. It worked fine prior to the SC change over from a deat battery.

The mod was just a shell swap.

What's curious is it's a subway car which is presumably not pulling 50 coal hoppers or whatever.  The motors should not be dissipating so much power that they sizzle.

Couple more ideas.

Lift chassis and manually rotate each flywheel several times in each direction.  Does "transmission" feel smooth and un-impeded?  Both flywheels should feel the same mechanical resistance as you turn it.  The idea here is that if the engine is behaving properly (you command 10 sMPH, it goes 10 sMPH, and so on), then a sizzling motor means too much electrical power is going in for mechanical work going out.

I like GRJ's idea of simply pulling the motor-plug with the 2 yellow and 2 white wires to the motors.  With the connector off, if you have a meter that measures resistance, measure each motor at a handful of angles of a flywheel revolution.  Not sure what motors are used in your subway but the resistance should be 10 Ohms plus or minus (that is, not 1, not 100). These are brushed/commutated can motors so there will be different windings in play but the winding resistance should match within a few tenths of an Ohm within a motor and even between motors of the same type.  The idea here is some kind of electrical fault with the motor is causing a huge drop in efficiency.  Of course hard to believe the same fault would exist in both motors but this should only take a minute or so to confirm so why not.

If you don't want to mess with pulling wires and don't have electrical measurement tools, I'm next thinking of having you operate in conventional mode with speed control turned OFF.  This will reveal a lot about motor performance.  It's an overlooked troubleshooting method that you can only do in conventional mode in PS2 - you can't turn OFF speed control in DCS command mode.  You need a transformer/controller that has Whistle and Bell buttons though.  More on this if needed.

While being a subway @ not pulling 50 cars. The 5 that is is pulling, being on a 6x5 loop may be a struggle. 

ALso the Z-1000 trans if at like 80 to 90% power to pull it around said loop.

perhaps the combination of the struggle & high power to do so is to much for it.

But again, never had a problem in the past. So IDK.

Question, did you put a different shell ont his or the same one? do the subway shells go on either way? Does it run this way with the shell off?  The reason I ask is that I hae had a coupel of locos that after putting the shell back on the flywheel was rubbing on the inside of the shell or the wire grabs on the inside. If your flywheels are rubbing that would put increased drag on the motors and increase the load. Since they have a tach reader the speed control will compensate for the increased load. The speed wont change but the current draw will

I always hated the graffiti set power car. So I switched if from one of the other coaches in the set.

Did this years ago. Never had an issue untill the SC swap.

Well, I'd stop looking at the SuperCap and look for other more likely causes.

Well I used another SC & all seems to be normal again.

Just going to take a while to get that stink out of the unit :- (

I was contemplating ordering some of these then I read this thread ...

Thanks for posting the result, I assume the motors are not heating up now ? 

Is there a way to pretest these before installing them ?

I have some 15 locos running on my layout using the Digikey supercaps, 2.5F, and have not experienced anything like this.  Like Stan, I am puzzled how the supercap could affect the motors.  Could it be that a rectifier in the board has failed and is feeding AC to the motors and the supercap???????