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RD50 112 Cap replacement

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guitarchuck
Posted on Thursday, February 16, 2006 - 03:25 pm:   

Hi I just ordered an old RD50 112 amp. I want to go ahead and get all the new capacitors on order, so I can re-cap it soon after I get it. Do any of you out there have a list of the caps that I need to order for this model?
Thanks,
Chuck
mike kaus
Posted on Friday, February 17, 2006 - 06:51 am:   

Don't have one but I looked over a schem and came up with this:

3--150mF@50v
2--400mF@25v
4--20mF@25v
1--2mF@350v
2--60mF@350v
1--2mF@25v

These are kind of quirky values in some spots and you will most likely have to do some subbing and raising of the voltage rating. Hope I didn't miss any. Mike.
guitarchuck
Posted on Friday, February 17, 2006 - 10:07 pm:   

Thanks for the info Mike. I downloaded the schematics after posting the note. I don't know why I didn't think of that first. I only came up with 2--150mF@50v. and I came up with 5--20mF@25v. All the others match yours. Would you recomend Sprague Atom caps?
Thanks,
Chuck
mike kaus
Posted on Saturday, February 18, 2006 - 05:46 am:   

Sprague's are great. So I can't count! See what happen when you wear glasses and don't put them on! Had them all marked and STILL miscounted. Mike.
guitarchuck
Posted on Saturday, February 18, 2006 - 09:36 am:   

Thanks Mike! It looks like I can't spell. I left an "m" out of recommend in my last post, lol. I have my caps on order. You mentioned in another post that you "rodeo tie" the caps above the board and it works for you. Exactly what do you mean by "rodeo tie"?
Thanks again,
Chuck
Trent
Posted on Sunday, February 19, 2006 - 06:32 pm:   

You can cut the old caps out as close to the actual cap as possible to give you a bunch of of the old leads to work with. This will allow you to avoid touching the old solder joints and possibly affecting parts of the circuit on the bottom side. What I did was cut the old caps out as close to the actual cap as possible, place the new cap in (oriented correctly, of course), twist the new cap's leads around the old one once (either hook or loop around), solder, and then cut the excess leads. You may want to take some steel wool to the all of the leads, especially the older ones, as they may be dirty. I also used small alligator clips to hold things in place and to act as miniature heatsinks to avoid any chance of heat traveling into the board and doing something disastrous. If you have a good soldering iron you should be in and out so fast these will all be way overkill, but better safe than sorry (some cliches become cliches for a reason).
guitarchuck
Posted on Tuesday, February 21, 2006 - 03:30 pm:   

Thanks Trent! Good info.
Chuck
mike kaus
Posted on Wednesday, February 22, 2006 - 04:23 am:   

Pretty much my procedure but I loop the ends in a little knot and solder. Old habit-nothing important. Like Trent says, if it's clean, yo can solder them so fast it doesn't get to the joint. It's very common for the heat to be on less than two seconds if properly done and clean. Mike