Replacing Bulging Capacitors On early 5 Volt Boards

I'm guessing you have other failing components, likely diodes.  A lot of the components on the 5V boards were running pretty close to maximum ratings, so their life wasn't that good.

If there is excessive voltage there, jacking up the rating of the cap is not the answer, and it's hard to see how that will address the real problem.

Hi if the board is not destroyed you can replace the 470 mfd with a 470 mfd 50 vdc and your problem should go away they did not use the correct voltage caps and that's why they overhear and bulge out!

477KXM063M Illinois Capacitor | Capacitors | DigiKey

here are the capacitors you need!

Alan

Thank you for the replies gentlemen. The engine has always ran fine and still is. I'm just trying to buy time with this board. So far the components, other then the cap, are holding up to the 24 volts. Just thought maybe someone may have seen this issue and knew where it was coming from. I'll upgrade the cap and hopefully she'll keep rolling for another year.

Alan - would preemptively replacing the existing capacitor with the one you recommend eliminate the tendency of the 5v board to commit suicide?

It's more than caps that are the issue with the 5V boards.  Also, I have seen no caps that were not voltage rated properly, the situation described above with the wrong voltage on the cap is abnormal operation of the boards.  I'm certain that there is something else amiss if he's getting 24 volts where a normally operating board has 12V.

The one cap that I've consistently replaced is the 330uf 35V cap if it's the WINCAP brand, those seem to fail a lot more often than any other.

Alan, the dimensions in the specs on that cap won't allow it to fit in the limited space on the board. The lead spacing is also wider. So I searched by canister size (taller not being an issue) and lower voltages, but had no luck on Digikey. So I tried on Mouser and found a 470uF 25 volt the correct size.

667-EEU-FR1E471Y

I can think of no circumstance where the nominal voltage in a circuit like that would double and it isn't a cause for concern, so I'd expect some failure sooner rather than later.

I agree with what John said I have replaced these caps with brand new ones and the new cap got hot immediately! like John said the voltage applied is too high and causes the cap to overheat!

Alan

Actually, my guess is something like a diode failure and the cap is seeing AC or at least excessive ripple, and that's what is causing the heating.

Makes sense. I'll dig deeper.

Alan, If a rated fuse constantly blows do you go get a higher rated fuse and stick in the circuit, or do you find out why the fuse is blowing.  The whole capacitor rating is wrong get a bigger one is bs.  You should know better. 

I think your chasing your tail on the 5V board once caps start blowing and you have damaged components beyond the cap Dave.  Not worth having it melt wires or shell in your engine.  I have test board gone bad that had direct PV shorts and pulled 7 amps.  If you don't have a meter to see it you wind up with a smoke meter.  Especially with a big transformer like a Z.  G

Thanks GGG for your reply. I received the 25 volt cap and installed it last night. I ran it around my test oval for almost a half hour, without the shell on, then felt the cap and it didn't get hot. Then ran it again with the shell on which added more lights and more weight. Tonight I will give it a real test and hook it to a long train when I go to the property where I'm building a new layout. I have a temporary dog bone set up, to pacify my addiction, while I move forward on the bench work. Looking at that 5 volt board and how it's built, just trying to find where the voltage jumps higher, looks dangerous and next to impossible. It may be possible, though, for a skilled electronic technician (hint hint) to study the schematic and pin point what component may have failed to cause the higher voltage and if it's even possible to get to it. But for me, because of my limited electronics knowledge and the design of this board, increasing the voltage rating was really the only option I had. The test tonight "will" start with a prayer.

Dave, separating the 5V board stack is simply not worth the trouble.  I did one and I spent a ton of time doing it without destroying the boards.  As far as "fixing" 5V boards, I do the obvious stuff that accessible, if that doesn't fix it, it hits my bad board box.

Good morning all.  I just re-joined the Forum after a number of years away from it.  I have about finished a project to exchange the NiCad/NiMH batteries in a number of MTH engines for the BCR1 (have not started in on the BCR2's as yet.)  With the exception of some old Proto 1 engines where the infamous chip scrambling had occurred in the past, all was going well until I hit the early Proto2 engines with the 5 volt boards.  Some of these engines have not been run in 17-18 years.  Most have come back without difficulty, so far, but I have had several die with exploding capacitors (I guess the rest are just waiting to go).  This prompted an online search, which of course led me back to the Forum.  I have read the posts on the Forum about this issue, and I would like to make sure that I understand both the issues and what fixes exist, if any.  So, with many apologies for the elemental and repetitive nature of some of these questions, here is a summary of what I think I know from my online reading.  If I am in error with these statements please correct me:

1. Early Protosound2 5V engine boards were shipped with inferior capacitors, and failure of these components is the most common (but not only) reason for board failure.  I assume this is true for all of the 5V boards or were the later ones made with more robust components?

2. Per GRJ's post above, it is virtually impossible to repair failed Proto2 boards, direct replacement boards are not available, and probably never will be?

3. Other than a Proto 3/2 upgrade, there is no way to prevent these failures from occurring?

4. The Proto 3/2 boards are not direct replacements, but they can be used as a component of a complete upgrade of the engine to Proto3 status.  In other words it does not remain a Proto2 engine and acquires most of the features of a Proto3 engine.  (I first heard about these boards from my friend Marty Fitzhenry - may he rest in peace).

5.  Non MTH electronic control packages can be installed (ERR?) but they lack the complete functionality of Proto2 or Proto3.

6. And while I know this last question is probably going to make everyone laugh, is there any hope that the newly slimmed down MTH is ever going to address this issue?  Their new website at MTH Parts and Sales of course says the PS2 boards are "out of stock," but some forthrightness like "will never be available" might be preferable.

Thanks to all

PRK

Actually, for the most part, the PS32 boards are a direct replacement for the failed PS/2 boards.  There are two different configurations of the PS32 boards, those with the 3V connectors and those with the 5V connectors.

A couple of differences.

The PS32 boards require a 4 ohm speaker, the PS/2 5V boards have a 16 ohm speaker.  That means you replace the speaker when changing to the PS32 boards.

The PS32 boards don't require a battery, so you leave that connection connection out.  Do NOT plug anything into the 2-pin connector on the top PS32 board that looks like a battery connector, it is NOT a battery connector!

The PS32 boards are a different form-factor, so there will be mechanical mounting modifications.  The heatsink provisions for the PS32 boards are different than any of the PS/2 board types, so that is something to deal with, there is a heatsink kit available.  The connectors are in different positions on the PS32 boards, so in certain cases, some wiring harnesses may have to be extended to reach.  Finally, the PS32 board stack is a different shape and doesn't always fit where the PS/2 boards did, in extreme cases you may have to leave off the plastic carrier for the PS32 boards and wrap them in insulating tape (I use Kapton tape).

Thanks very much GRJ.  I have two engines I might like to get repaired with the 3/2 board, an Erie Triplex (20-3069-1) and the DAP BNSF GS4 (20-80003A).  The latter engine has the blown board in the engine boiler (tight fit) so I imagine there would be some modifications needed.  Are the boards available, or also "out of stock?"

They're currently "out of stock", but hope springs eternal and maybe someday they'll be available again.

Thanks again.  So for the moment these engines are nice for display and not much more.  I am sure that many of us who invested heavily in MTH products in the early 2000's are pretty bitter right now.

Best

PRK

Yep, the old PS/2 5V boards were not stellar performers.

@gunrunnerjohn posted:

Yep, the old PS/2 5V boards were not stellar performers.

PS2 3V on the other hand seem to be great. I've got a few that are 18 years old with a bunch of run time that work great.

@Lou1985 posted:

PS2 3V on the other hand seem to be great. I've got a few that are 18 years old with a bunch of run time that work great.

Yep, I personally think they were the best of the lot.  The PS/3 boards have not been that robust either, and now with minimal support for the firmware, I worry about their future.

It was not necessarily early boards.  It is a little more complex.  PS-2 5V have many variations in production, like the TIU.  Rev G, H, I , K  So it was evolving.  There are plenty of original 5V boards working fine to this day.  Just repaired one last week. Other models like the FEF Northern seemed to fail in high numbers with very little use, just age.

For your premier engines make sure you use a tech that puts the board back were the original 5V board is.  Some just do an upgrade and stick it in the tender and you lose all the light features.  PS-2 3V boards can be used to do the repair if some one has them available.  I come in to them occasionally.  But as stated now adays it is the PS-32 with proper flash code and then can use the orig sf in 3V format, or even a newer PS-3 sf with enhanced sounds and quillable whistle.

The other thing you might see is a crumbling speaker magnet.  So look at it closely.  If the 5Watt Star with large magnet, it can be bad and needs to be replaced too.  Otherwise sounds will be low/distorted or missing.  G

I also have a number of PS/2 5V boards that still work fine.  I'd love to know how to spot the bad revisions, but I've never seen a primer on how to identify the versions that are prone to drop dead.

It was not a specific version.  The Rev # is under the rectifier at front of board.  Why a specific engine model had issues is probably a small batch defect on those boards.  In other cases a combination and some component that fails leaking high than voltage or current causing issues. No longer worth the effort as far as I am concerned.  Fix a light fet, audio amp, or motor fet.  Otherwise replace it.  G

@GGG posted:

Fix a light fet, audio amp, or motor fet.  Otherwise replace it.  G

That's certainly been my approach to the 5V boards.  Obvious failures  that I can reach I fix, the rest I junk.

Unfortunately, based on what both of you have said there is no easy fix.  Once the 5V board is gone as there are no parts currently available to replace it.  Pretty discouraging.

One can only presume that someday the PS32 boards will again be available...

It would be nice if the current version of MTH would step up to the plate - if memory serves, when the company re-organized and downsized they did create an electronics division, didn't they?  Producing a sizable number of the 3/2 boards would be a nice gesture for those of us who hitched their collecting star to the Proto2 revolution in the early 2000's.  They might even be able to make some money off it too...

PRK

Dear Friends,

After reading the above, I feel sorry for those of you with Proto 2 and possibly Proto 3 engines that use a 5V board.  Since there aren't any replacements, there aren't any options open to you for repairing them and keeping the command system DCS.   

As a question, those who are in this situation, can the engines be converted to a Lionel based command system instead?   

Could they even be converted to run conventional without the fancy features that DCS offers?

This way they won't be pretty shelf queens.

Well, I suspect the global semiconductor shortage has something to do with the issue.  OTOH, since they're producing PS/3 locomotives, they obviously have at least some quantity of the parts to build the PS32 boards.  PS32 boards are basically the same design as the diesel PS/3 boards, just different form-factor and connectors to accommodate the stacker interface board to make them look like a PS/2 board.

Several days ago I emailed MTH Parts and Service to see if they had any plans to produce new Proto2 boards.   I pretty much knew what the answer was going to be - an emphatic no - so I have sent them another query asking if they had any plans to produce more of the Proto3/2 boards.  I will post their response when I get it.

Of course they will.  They are just out of stock right now.  Everything board wise goes to new product first.  The PS-32 is in the upgrade kit for steam.  PS-3 diesel is in the upgrade for diesel.  PS-3 steam is in new production.  Up until this week I had all versions of the boards in stock but they were expended over the course of the year for repairs.  I do have 5 steam upgrade kits left.  Your just getting back to this, but this ebb and flow of parts alway occurred.  But it may ramp up between Covid, inflation, and now political warfare along with a real war in europe.  Toy trains are on the bottom of a priority for an electronic manufacturer making the boards.  I get it though; your disappointed and can't get immediate satisfaction. 1 month ago and you could have from me and probably a few other techs.  The reason PS-2 is gone is obsolete parts to make the board.  Infact even common repair chips are harder to get and on end of life cycle.  PS-3 was made because PS-2 could no longer be made.  They made PS-32 specifically as a replacement repair part for PS-2.  G

The only question about the PS3/2 boards is when the chip supply catches up with the smaller manufacturers.  The people that are making 10,000 or 100,000 boards are getting the chips first, but even car makers can't source chips!

I've been having a lot of trouble getting chips for my boards, and I'm a really small manufacturer, so I'm at the very end of the line!  I'm hoping my existing stock holds out until the chip production recovers enough to start filling the supply chain again.

Thanks to you both (GGG and GRJ).  Of course it makes sense that the worldwide semiconductor/chips shortage impacts this very small fragment of the market.   I guess I should not whine quite so much, but it remains frustrating.

@GGG posted:

I do have 5 steam upgrade kits left.

GGG,

Are these the PS3 Steam upgrade kits?

I received an email back from MTH Parts and Service indicating that they will be making more of the PS 3/2 boards, but that there is no ETA for them as yet.

GGG, as I understand your post above, the PS3/2 board is a component of the PS3 steam engine upgrade kit?  I am sure you would probably prefer to keep them for full PS2 to PS3 upgrades, but is there a possibility that you would be willing to use them for repair of blown PS2 boards?  Or, (and this is a really dumb question), does it essentially amount to the same thing?

The PS32 board is close to a direct replacement for either the 3V ot the 5V PS/2 board.  The form factor is slightly different, and it needs a different heatsink.  To replace a 5V board, you also need to replace the speaker.  There are two versions of the PS32 board, one with 3V PS/2 connectors and one with 5V PS/2 connectors.  They are otherwise identical in form and function.

All the connectors on the PS32 board match the connectors on the PS/2 boards, but they aren't arranged the same on the board.  This occasionally requires a lengthening of a wiring harness, but most times they reach without modification.

I may.  I am not selling them, and I am expecting some upgrades, but I probably will expend the board for repairs; and back fill when they become available again.  So if you have a repair you need done, can contact me via email in my profile. G