Preventing old protosound 2 (5 volt) board from blowing?

Hello everyone, I recently brought a MTH r32 protosound 2 subway set. For a quick summary this set was made around 2003, back when protosound 2 boards came with 5 volts. I've heard that I have to replace the battery every 5 years to prevent the battery from destroying the board. Is that just it? Do the boards just blow up on their own or is it really do to a battery issue? The seller told me he hasnt run this set in 10 years, it was working the last time he used it but obviously the battery is aged now. I have a new mth 9 volt rechargeable battery ready to be installed in it. Do I have to get the mth battery recharge to endure the train does not go bad? All help is appreciated thank you 

Original Post

I have a number of older PS2 with 5 volt boards. Luckily (knock on wood), I've never had one go out yet. The biggest problem is the capacitors that were used during the manufacturing of these boards. They are prone to premature failure and that is will ultimately cause the board to fail. 

I use the DCS system to check the batteries in my engines and also make sure that they complete the shutdown sound sequence to ensure the batteries are good. Generally, I've been getting 5 to 7 years of life from my batteries, sometimes less, sometimes more.

 

H1000

Some of these 5v boards seem to fail even with a fresh fully charged battery.  The weak component seems to be a 330uf  @ 35v capacitor   It can be removed  and replaced without separating the boards. According to GRJ this is a common failure point.  When you do make sure you follow good static discharge prevention protocols and use an ESD safe iron.   Make sure to note the polarity of the cap in the board before you remove it.  I bought a bag of these caps and have replaced it one of my four 5v boards and it's still working .  In the early 2000s there was a virtual pox of bad chinese caps and I would imagine this one of them.                      j

Just got another 5V board with the infamous 330uf cap bulged and the board is indeed dead.  I don't know if that's what killed it, but it didn't help, that's for sure.

I think the primary reason for the failures is the 5V board design runs a number of the components right at the limits, the motor drive FET's are one such part.  I personally had one die, and I've gotten two others in for repair that died, all for the same reason.  Throw a traction tire, jam the power truck, and if you're not lightning quick, the overload smokes the FET.  Of course, the funky heatsink they used on those is almost impossible to get back on right without overheating the FET, so out of three, I only managed to fix one of them.  There are also several diodes inside the board stack that die, I don't know if that's caused by another failure, or they're the cause of the failure.  Since it's very difficult, bordering on impossible, to split the boards to fix them, that's usually a death sentence for the set.

gunrunnerjohn posted:

Just got another 5V board with the infamous 330uf cap bulged and the board is indeed dead.  I don't know if that's what killed it, but it didn't help, that's for sure.

I think the primary reason for the failures is the 5V board design runs a number of the components right at the limits, the motor drive FET's are one such part.  I personally had one die, and I've gotten two others in for repair that died, all for the same reason.  Throw a traction tire, jam the power truck, and if you're not lightning quick, the overload smokes the FET.  Of course, the funky heatsink they used on those is almost impossible to get back on right without overheating the FET, so out of three, I only managed to fix one of them.  There are also several diodes inside the board stack that die, I don't know if that's caused by another failure, or they're the cause of the failure.  Since it's very difficult, bordering on impossible, to split the boards to fix them, that's usually a death sentence for the set.

Another case for gluing the traction tires on.  I had a Williams loco back in the early 90s burn up a Dallee eunit that had just been installed a month, with just such a traction tire in the gears. Since then I glue them on. It's not 100% but usually they stay on till their disintegrating and if they do come off it's in small enough pieces that they are not likely to jam in the gears.  Two ~ three years ago I was changing the tires on a MTH  F3 and decided to glue the tires on one truck and not on the other the unglued tires failed in about a year. They did not tear, just stretched, and would not stay on. In my opinion this is the situation most likely to get the tire jammed in the gears.  I thought for years about installing a fuse between the motors and driver to limit current draw and it was your suggestion of poly fuses that got me moving to do something about this.  I installed them on all my TMCC and DCS conversions in the last six months and working my way back through earlier conversions and mfg original command locos. let me mention this,  talgo trains such as Zephers, AeroTrain and UP  M-10000 which have a motor truck on each end of the train have a wiring harness most susceptible to melting down when the tail end car jumps the track or splits a switch shorting the center rail pickup to the outer rail on one end of the train. This can cause not only the DCS TMCC boards to fry it can fry the entire wiring harness the length of the train.  Why Lionel or Mike would not address this flaw is just a big ??  I bought a new MTH  M-10000 several months ago and have not put it on the track yet or until I can figure a strategy on where and what size poly fuses to install.     j

nycboy posted:

So it's just a design problem? **** upgrading the sets will be alot. The route cause of it is the capacitors? Can I just replace the capacitors on the train and may help survive for a very long time?

Not really.  There are many causes for the boards to fail, it's just that I see this one particular cap failed more than any others on the board.  You can't get to most of the caps to replace them, even if you wanted to.  It so happens that if you prop the boards apart enough to reach in with a skinny soldering iron, you can replace the 330uf 35V cap, so I do that whenever I see the WINCAP brand.  I replace it even if it doesn't appear to be failing, I strongly suspect that brand was one of the ones affected by the Capacitor Plague of the early 2000's.

JohnActon posted:
gunrunnerjohn posted:

Just got another 5V board with the infamous 330uf cap bulged and the board is indeed dead.  I don't know if that's what killed it, but it didn't help, that's for sure.

I think the primary reason for the failures is the 5V board design runs a number of the components right at the limits, the motor drive FET's are one such part.  I personally had one die, and I've gotten two others in for repair that died, all for the same reason.  Throw a traction tire, jam the power truck, and if you're not lightning quick, the overload smokes the FET.  Of course, the funky heatsink they used on those is almost impossible to get back on right without overheating the FET, so out of three, I only managed to fix one of them.  There are also several diodes inside the board stack that die, I don't know if that's caused by another failure, or they're the cause of the failure.  Since it's very difficult, bordering on impossible, to split the boards to fix them, that's usually a death sentence for the set.

Another case for gluing the traction tires on.  I had a Williams loco back in the early 90s burn up a Dallee eunit that had just been installed a month, with just such a traction tire in the gears. Since then I glue them on. It's not 100% but usually they stay on till their disintegrating and if they do come off it's in small enough pieces that they are not likely to jam in the gears.  Two ~ three years ago I was changing the tires on a MTH  F3 and decided to glue the tires on one truck and not on the other the unglued tires failed in about a year. They did not tear, just stretched, and would not stay on. In my opinion this is the situation most likely to get the tire jammed in the gears.  I thought for years about installing a fuse between the motors and driver to limit current draw and it was your suggestion of poly fuses that got me moving to do something about this.  I installed them on all my TMCC and DCS conversions in the last six months and working my way back through earlier conversions and mfg original command locos. let me mention this,  talgo trains such as Zephers, AeroTrain and UP  M-10000 which have a motor truck on each end of the train have a wiring harness most susceptible to melting down when the tail end car jumps the track or splits a switch shorting the center rail pickup to the outer rail on one end of the train. This can cause not only the DCS TMCC boards to fry it can fry the entire wiring harness the length of the train.  Why Lionel or Mike would not address this flaw is just a big ??  I bought a new MTH  M-10000 several months ago and have not put it on the track yet or until I can figure a strategy on where and what size poly fuses to install.     j

Wouldn't fast blow fuses between the power supply and track address the issue of burning up boards? I've been using fast blow automotive blade fuses between the power supply and the track and have yet to fry a TMCC/PS2 board because of a derailment.

Santa Fe, All the Way

If you run the same number and size locos all the time you might find a value that gives you some protection but what if you have 10 locos on your command layout knowing that each one can pull 5A starting a train and 1.5A running a steady speed what value fuse are you going to use 50A ?   15A ?  Where in between ? The fuse between the power supply and the track is for protecting the power supply not the command boards in the loco. Perhaps on occasion they might save a board that is just happenstance. So that fuse would be sized to protect the power supply.  The place for a device to protect the locos boards is between the motors and the motor driver board and perhaps between pickup rollers so that a derailment can't burn up the wires between rollers and boards.  This is a problem on multi-unit locomotives where there are pickups on each unit and if one should derail and one of  the pickups find outside rail "common" it creates a short through all the wires running between pickup rollers. If these wires run through the wiring harness in a multi unit loco or a talgo type train such as a GM AeroTrain, a Zepher, or a UP  M-10,000 you can loose the entire wiring harness from the loco to the rear car. This kind of short would likely blow your fast blow fuse protecting your power supply also. Something I discovered is the super flex wire with silicone insulation can stand up in short conditions much better than vinyl covered wire.  I originally started buying this wire just for the extra flex it gives on pickups mounted on trucks that swivel, but noticed the added benefit    So I now add protection from overload and shorts in three places  between track and power supply, between pickup rollers and between motor and driver board. That includes spike protection for which I use TVS diodes in addition to overcurrent protection.  j

I have repaired motor fets before, but very few.  This subject always creates a life of it's own.  Motor fets do not kill boards.  Many more components on the board that do that.  Batteries do not do it either.  I have seen plenty of operating 5V boards that still had white batteries in them.  Not sure the PV cap does it either, though they do fail at a high rate.  There were so many revisions to this board as it was used too.  Too many generic conclusions being applied.

I can say there are some engine that seem to die at a much higher rate.  The R21 Red bird and the UP FEF are ones for sure.  Others seem more random.  G

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So I just finished replacing the battery and put power to the powered car. Relay click came on and it powered up just fine speaker was muffled though. With in a few seconds the 330uf capacitor exploded. But the weird thing was the train was still operating, lights and sounds were still playing. I quickly cut the power to prevent the board from getting destroyed. It seems like the board is still operational but the capacitor obvisouly needs replacement. How can I take the apart this board to replace the cap? It seems like its glued on so I can't get to it.

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Do you have a ESD safe soldering iron ?  Do you have anti static bracelets ?  You can just work near a copper water line and touch it before you grab the board and every couple of minutes there after.   Wearing all cotton clothes can't hurt either.  No nylon, polyester or wool. SOCKS !    Static discharge is more a problem in dry cold winter conditions.  As bad as that cap failed you may just cut as much away with needle noise pliers and wire cutters. Careful, don't cut or break anything else. Once you have it mostly removed heat the leads that pass throught the board one at a time prying on that side of the base of the cap. Now heat the other lead and pry on that side of the base. Rocking it back and forth till you work it out. Clean out the holes and install the new cap. BTW; shorter caps with that same value are available and will make it easier to get in. Hopefully you will never have to remove it. Make sure to note the polarity of the leads on the old cap before you remove it as you must install the new one the same way.  j

Your speaker is bad and flaking, so it needs to be replaced.  You can reach a tip in to desolder especially since the cap has separated.  Clean out the hole so a new one can go it and solder it in place.  G

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You do not have to separate the upper and lower board. You do have to match the resistance of the speaker.  Lionel has them and you can find them on eBay.  I have also found usable speakers in small computer speakers, earphones, old transistor radios.   j

A question from an electronics ignoramus to the respected electronics gurus here.....I have a bunch of 470uf, 35 V capacitors that I bought for a project suggested some years back. By the time I found the time to do the project, I forgot what the project was and now am stuck with them. It's tough getting along in years.....sometimes.

Is it possible to use these in place of the 330ufs?

Thanks,   Joe

Truthfully, while they might work, I wouldn't fool with the values used here, the 5V boards are flaky enough.

As far as putting the cap on, I just gently pry the boards apart far enough to get my long tipped soldering iron in and solder the cap.  As George mentioned, getting the old one out is easy, bust it apart and then unsolder the leads from the top.  You're lucky that the board survived.

actually you should only use 330 uf but 50 vdc other then that you'll be ok !

as far as the speaker in concern the one you picked on ebay will work just  solder your yellow and white wires where the red and black wires are already located!

make sure you do not solder the wires and they stick out and ground out on the metal of the speaker as that will blow the board and or audio amplifier on the ps 2 board!

 

This scenario raises both an electrical engineering question as well as a mechnical question.          One can often substitute a higher voltage rated capacitor in a circuit, however since I do not know all the circuit actions going on in this board I won't judge the wisdom in doing so here. However when you go up in voltage rating the size of the cap may get larger and not fit back in the space allocated.  So when you purchase your new cap check the diameter and height to make sure that it will fit in the space the old one was in. The spacing between the leads can also be a factor since if it is not the same you may not get the cap seated flat on the board and it may not fit in the space between the two boards.          j

Well would it be more practical to just replace all the capacitors then? But im gonna assume you cant really separate the board, I tried really hard but it wont separate so I'm gonna stop trying so it doesnt breal something vital. I wish MTH provided some diagrams of the board or how a powered car is operated

Im gonna butt in here. I seen 3 different "failures" to the proto 2 boards.

1) boards that short out. (Most common from what i seen) 

2) the boads that die, (no power going through) 

3) i seen a board or 2 with the cap physically blown out. 

is there a way to determine if the capacitor is bad? if #3 happens its obviously the capasitor, but what about option one and two, would that be soley from the capacitor? Is there a way to test the cap?

There are PV diodes that short in the middle of the board.  There is a power FET that can short or fail that seems to control board power up.  They can lose the ability to see DCS, the processor just fails.  The one 35V Cap fails and either pops or expands and pushes off can.  They have power and create 5V and PV voltage, but just dead with no current draw.  There are other faults like shorted fets for lights, audio amp blows, motor fet shorts. 

If one shorts but is left powered up, it shorts until the component fails open.  At which point it looks dead with no current draw.

There really is no way to know for sure unless a failure analysis was done.  The design engineer might have insight, but they have moved on to different stuff.

This board was a 2000 to about 2004 run.  Granted a lot of trains built in that time frame, but there are solutions if they fail.

Trying to figure out how to prevent a failure is like trying to determine how you will prevent a stone chip while driving your new car to work every day on the highway.  These boards are about 18 years old.    G

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GGG posted:

Trying to figure out how to prevent a failure is like trying to determine how you will prevent a stone chip while driving your new car to work every day on the highway.  These boards are about 18 years old.    G

Very true! And as for the boards. They are old technology wise. As what one of my friends would say "its old enough to vote!" 

Thanks for the info!

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