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The 9V battery eliminator probably should have the diodes to balance the charge.  OTOH, the 3V one using a 5V supercap needs no diodes, just the supercap.  I've done dozens of these, they plug right into the PS/2 power board and you can eliminate the charging harness.  When I do upgrades, I supply one of these to avoid having the extra hole in the tender that I have to drill and shape for the square connector.

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  • mceclip0

That's what I was thinking but guess they have a different plan. Can't imaging Dallee did not try it the way they show and I do hate soldering those tiny zeners on, may try and make one without them. I developed a tremor in my hands a year or so ago and over half the time to make them is soldering on the zeners.  Let you know if it fries something.  jSuperCap-Wiring

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If the two caps are identical, you will probably be OK, though there's no certainty.  The issue that the Zener diodes address is uneven charging, that happens if the capacitors are not well matched.  I doubt you'll fry anything, but if one of the capacitors see more than about 5.4 volts, they will likely fail in a fairly short time.

Note that those individual packages actually have two round 2.7V capacitors in them, and they're in constant use all over the world, so I suspect the caps are pretty well matched.

I know about matching caps. I did product and industrial photography for years and had some big strobe packs. When the caps in those strobe packs blew it was like a firecracker going off. When one cap blew I would buy eight new caps and insist they were all from the same mfg lot. Even then you had to make sure they were fully formed before you put them in the circuit. If you did not have them in an identical state the weak one would blow taking the diode bridge with it. I forget how many diodes were in the bridge but they were all cast into one long strip so you could not just replace the ones that blew. It was bad enough that I bought a Sencore capacitor analyzer.  Ascor eventually went out of business and I still wanted to use the 2400ws packs for location work so I had to find solutions to the problems the packs had. I made my own diode bridges so I could replace bad diodes and not toss the entire bridge. Eventually I switched to 500v Cornell caps from the 360v Siemens. Ascor was trying to keep their strobe packs light and cram as much power into them as possible so they ran the caps with very little headroom, at 330v and it was just to hot. They had a good charge circuit and I was able to turn the regulator up to 400v when I switched to the Cornell caps and though they were only 2400uf vs the 2600 for the Siemens total power went up. After I put the Cornell caps in those packs I never had to rebuild them again. Which I was very happy about as they are a scary beast to work on.                                        A question about the 330uf cap on the 5v PS2 boards.  Are you able to get the old cap. out and a new one in without separating the boards ?  I was thinking about crushing the can and see if I could pop the end off the can. I like to be able to remove the leads from the board one at the time rather than heat both at the same time.  j

JohnActon posted:

A question about the 330uf cap on the 5v PS2 boards.  Are you able to get the old cap. out and a new one in without separating the boards ?  I was thinking about crushing the can and see if I could pop the end off the can. I like to be able to remove the leads from the board one at the time rather than heat both at the same time.  j

My method is to heat the closest lead to the edge and rock the cap as far away from me as possible, then do the other lead.  A couple of passes like this and the cap is out.  I clean out the holes and solder the cap in.

In order to give myself as much space as possible I "spring" the boards as far apart as I can without breaking something, that allows me to slip the soldering iron tip in and get to that cap.

I've done at least half a dozen of these, a couple were malfunctioning, but not totally dead, that brought them back.  The others were functional, but the cap shows signs of failure, either a bulging top or starting to ooze chemicals.

Thanks John,  eight MTH locos four with PS1 and four with 5v PS2 boards Wish I could afford to put all new ERR boards in all of them but that ain't gonna happen $      So, the plan is to add BCRs  and new 330uf caps to all the PS2 5v boards. UCUBs in three PS1 and I have two PS2 3v boards and slaves for an AA centipede and an ABA F3 if I can sort that slave thing out. This will take me through the first of the year at the rate I work.   j

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