Thoughts?? Blue Output Caps MS2125 and MQ430s

[st3v3vo]

I have a couple MQ430s and 2125s that I want to replace all of the power caps on. I know many don't feel replacing the output caps is necessary but I would rather not take chances and have to do things twice or worse burn a board.

MQ-430s
35 x 35 25v 15,000uf

MS-2125s
35x35 40v 10,000 uf

I can't seem to find any Vishay Sprague Caps that are in stock anywhere, but they do make them. I could order 600 of each bulk but that would be ridiculously expensive just to maintain the original aesthetics.

What are everyone's thoughts on best alternatives to use that are also blue in color?

What about just finding a replacement and using blue heat-shrink tubing to maintain the aesthetics?

I have found others replacements that are not blue but the lifetime hours aren't 5 or 10k; Do you guys think this this really that big of a deal or just a nice to have when replacing the caps?

[ttocs]

you can always get colored shrink wrap and make them what ever color you want.

[vwdude]

I'd keep looking for the blue. Where have you looked so far?

I've ordered them before and they showed up a week later even though they were "out of stock". Maybe call, or just order them and wait.

[st3v3vo]

Ive been searching DigiKey, Mouser, and Newark. The only blue ones that I can tell that might be stocked are the Cornel Dublier and they have a lead time of 21 weeks on some of them.


Ill keep searching until I find something or give up and use shrink wrap or just go with Black.

[vwdude]

Call Digi-Key. I've found that they have stuff in stock but don't always show it in their webpage.

[ttocs]

I just got 430 caps but they are all black

[st3v3vo]

Ttocs,

Can you link me to the caps you used?

I found some black Panasonic's for the MQ's from a place that still has them in stock, they are black also.

I cut the wrapping on one of the old Caps and the outer cap has an aluminum shroud so; which ever caps I got with, Ill just heat Shrink them blue and call it a day with a win over my OCD.

[Eric D]

Covering them in blue heat shrink just for the sake of making them blue does not make any sense to me over using black, which will then have the proper documentation on the side of it (capacity, voltage, polarity, etc).

So unless you plan on printing the proper info on the blue heat shrink, making them blue would be a hack job at best.

Also, you make the following statement...

I know many don't feel replacing the output caps is necessary but I would rather not take chances and have to do things twice or worse burn a board.

Replacing the rail caps when they are not physically damaged "IS" taking a chance. These caps are known as "snap in" style, and at the factory the act of installing them slightly damages the vias where it distorts the holes at entry. Even using the proper techniques to remove the originals runs high risk of further damage to the vias, which then requires more effort to repair. Also, if you happen to make a mistake, and the via is damaged to the point where electrical conductivity is lost from the top side to the bottom side of the board, several components down stream (in the output gain stage) can be damaged due to voltage over their ratings.

From experience I can tell you it is no fun to replace the rail caps, then measure the vias as good, only to have the amp fail on the test bench, then have to take all of those screws back out to extract the board and find that one via was only holding by a thread, enough to then fail under load testing.

With plenty of other electronics, none of this is a really big deal, but in the case of these amps you have a combination of a snap in cap, a beautiful looking but actually very fragile gold plated board, and significant age on the fiberglass of the board (20+ years now). I have said a lot of nasty words over the years working on these MS amps. Yes, I still think they are great, but they can be such a pain in the ass. I have worked on enough of these to loose count many years ago, and I have seen all kinds of crazy failures. If you want to replace the rail caps, I cannot force you not too, but I just cringe every time I read about someone getting ready to do this.

[st3v3vo]

Eric,

I appreciate your input; wrapping them in heat shrink would be the least desired method and I would have them labeled with the correct ratings etc.

As for the possibility in damaging the board; I will take your advise and use caution with anything that I do. I plan on replacing the caps as I feel they need to be replaced. Its as much of a learning experience as it is gaining a skill when working with electronics; if you break something learn to fix it and fix it properly. I don't half ass anything that I do and I take my time as well as have the equipment to solder/desolder (with variable temps and low temp alloy), and repair. If any vias were damaged I can use a couple of different repair techniques including eyelets if necessary. Im also planning on purchaing a hot air rework station but thats mainly for board level repairs on computers.

[vwdude]

I found that the best technique for removing rail caps is to melt new solder into the pad before trying to remove any. It seems that with that method you can remove the solder more completely and I've never had an issue when doing it that way. Of course it should be said that I take great care to have the proper sized tip on the iron, have the temperature set properly, use a large solder sucker, and I am a good judge of how long to hold the iron there. If you are skilled at soldering then I'm sure you can do it. Just take great care when doing it.

[st3v3vo]

Thank you. I take good care when I'm soldering and I usually let the iron heat up ima lower setting first and the turn it up until I can melt solder at the lowest possible setting. From there I use flux and melt into the joint, and don't let the iron sit long on the boards at all. I also use a horse shoe tip but have pencil tips as well.

[ttocs]

for desoldering I have always prefered a desoldering iron myself. Normally only takes on or two sucks on the ball after a short heat up and cleans all around the joint and inside the hole.

https://www.radioshack.com/products/rad ... oCqynw_wcB

[Eric D]

A desoldering iron is great for cleaning out stubborn vias filled with solder (sometimes wick just won't do it).

It is bad for removing parts though. It leaves solder between the part and any portion of the via or trace it is touching. Then when you pull the part out you take a small piece of via with you (or worse).