Do I really need Desoldering for replacing resistors/caps?

Thank you very much for your advise.  

Older solder oxidizes and stops wetting leads/pads.  In order to obtain good solder joint you need flux.  Flux serves two purposes - it cleans surface and prevents oxidation. Flux can be delivered with new solder containing flux or flux syringe.  If you don't have flux syringe you have to add substantial amount of new solder ending up in excessive amount of solder.  That's why you have to remove existing solder first  (In process of replacing SMT parts old solder is often left on the pads but then new flux from syringe is added before soldering).  Yes, you can make it easier by cutting leads of old components, but you have to remove old solder.

I do it different. Avoid de-soldering if possible. I sacrifice the bad component. Cut it apart with diagonals until interior leads are accessible. Grab one lead with forceps. Apply just enough heat to extract the lead. Do the other leads the same way - individually. Don't rock it out. Put a probe at the solder filled hole. Apply heat until the probe slides in (sorry). Allow the solder to set before removing probe. Insert new leads. Apply heat and add a little fresh solder until it all flows; and, Bob’s your uncle.

Thank you terry9 and Jim.

i don't know the age of the unit you're talking about but if it's older than 5 years it'll have lead solder, and now (certainly here in the UK) lead solder is a rarity, the lead-free stuff doesn't play so well with leaded, so if you did decide to do it, and the unit is of an age where it's leaded solder, best to remove as much of it as possible ... you'll still have a surface covering and thats ok, but mixing a blob of one with a blob of another is not so good

just my 2pennyworth, and my first post here having lurked for some time but only recently signed up

cheers guys

Jim

Eddy, in my home town the local high end store also does car audio. Their installer is superb - Mercedes quality or higher (and I own Mercedes).

I suggest that you visit a few car audio stores, and when you find the best, go into the shop and meet the installer(s). If you find someone you like, ask him if he could recommend someone to help you rework your ARC. You may well get lucky.

Thank you very much everyone for many good advice.
Wow, I guess I will have to put a hold on recap, seem like very difficult to me. I guess I can do some resistors with no problem. 
Do I search for "Audio repair" online for a good qualify LOCAL tech do to recap for me or should I use any other words. I don’t really want to ship it to somewhere else if I don’t have to and also I can ask him if I can watch him while he do the job and can learn from him.

+1 to grannyring. That's how I do it too!

Sorry, meant to say, "But it is a skill, and good REWORK equipment makes it a lot easier."

Eddy, gs5556 obviously has experience with the very units you wish to modify. I would take his advice very seriously.

Soldering is not a very difficult skill, but it is a skill. I would not start on something which is towards the difficult end of the spectrum.

Soldering fumes are not that bad, but not that good, either. It would be a good idea to do it outside or with a fan sweeping the fumes away. Also, there are several types of solder - make sure that you are using a solder which is suitable for electronics (typically resin core), otherwise you risk corrosion which may kill your ARC.

Also, make sure that the solder sucker has a high temperature tip. Back in the day, some were made with teflon, which is not a good choice for anything more than 460 F, because teflon can begin to decompose at that temperature, and the decomposition products are bad, bad.

Don't want to put you off, because modifying good equipment is the best route to great equipment. But, it is a skill, and good equipment makes it a lot easier. If you are doing just the one piece, you might want to get a good tech to do it in his spare time. If he will let you watch, you can learn and take pride in being involved in the upgrade.

Here’s the solder sucker and iron in a single unit.

http://www.mcmelectronics.com/product/TENMA-21-8240-/21-8240

I have one of these and it is much easier to use than a separate sucker and iron or the iron with the attached pump.

You will need a decent iron to melt the existing solder.  Make sure it can get hot enough and more importantly has a tip of sufficient mass depending on how much metal is connected to the joint you are heating.  I would skip the desoldering irons as it is basically a soldering iron (which you will need to buy anyway for reinstalling your caps) attached to a bulb pump. 

Then all you need is a solder sucker to remove the old caps.  I've used the cheap plastic $5 ones but the one I recommend is the Engineer SS-02.

http://www.amazon.com/Engineer-SS-02-Solder-Sucker/dp/B002MJMXD4

It has a flexible silicone tip that can withstand the heat of the iron.  Just place that sucker (no pun intended) over the whole joint while your iron is on it, and it will form a seal around it for effect solder removal.

I used $5 solder sucker and figured that desoldering iron works substantially faster and better.
Using solder sucker might require extra helping hands.

Simply use a $5 solder sucker. Heat up the solder joint and simply use the solder sucking gun to remove the solder. Very easy and effective. 

Recapping looks deceptively easy. Desoldering guns work great on through hole points but not where snap in components are soldered to voltage or ground planes -- the planes suck up the heat from the gun and it takes longer to melt the solder, if it does at all. You will have to suck away solder, resolder to build another heat bridge and repeat the process -- all the while tugging at the cap to get it loose. You then have to make sure you don't rip out the hole plating -- which can happen if there is not enough heat to melt the solder in the hole.

To remove caps from voltage planes requires a heat gun or a rework station. The planes have to be pre-heated to the point where you see the solder waving a bit, then you can apply the desolder gun and that puppy will fall right out. Same thing to solder the new cap -- preheat the plane and the cap leads and then quickly get the iron on the cap lead/plane and melt a few inches of solder on it.

Also, ARC products are not very friendly for repairing. They tend to overlap capacitors (the expensive Rel-Caps) over resistors on opposite sides of the board requiring you to remove those perfectly good caps to get to the resistor holes to desolder and solder. Also, they run a lot of wiring and they solder them to a common point -- and under no circumstance try to remove those unless you have a heavy duty industrial gun. If they get in your way you may be stuck.

Be prepared to spend some time. It took me the better part of two weekends to recap my AR 100.2 -- and I have all the bells and whistles and can solder in my sleep. Problem is I had to disassemble a lot of things to get to where I could access the components, including removing the expensive Rel-Caps. That job would have been impossible with just an iron and a roll of wick.

Thank you very much everyone for good advice.

http://www.amazon.com/gp/product/B0019V5MAC?keywords=desoldering%20wick&qid=1456936131&ref_=...

Above is by far the best desoldering vick I have come across.

Best of Luck

Peter

Agree with kijanki.  Unless you were going to do a massive amount of desoldering, a pump and desolder braid, work just as well and costs much less.

You could get manual desoldering pump for $4.50 or solder wick 
http://www.parts-express.com/Search.aspx?keyword=solder%20wick&sitesearch=true
Kester #66/285 is a proper solder - eutectic Sn63/Pb37 is the best for small electronic parts while 285 flux is mild and can be left on the board.

Thank you very much czarivey. Really appreciated your help Sir.
Eddy

I use Weller, but it’s hard to find. Had purchased mine 10 years ago 4lb.
I would not recommend neither tin or ones with silver added. Make sure you're bellow 200-Celcius range of melting Will be impossible to work and will require high heat which you often don’t want to use on circuit boards.

Thank you very much.  Any good solder you recommend?  I have a Kester 66/285.

You can use old solder, but fresh one is always better.
If you spot cold solder joints or cracked with magnifying glass, than you simply can re-touch the old one .
try to go http://www.parts-express.com/cat/desoldering-tools/520 and choose 45W desoldering iron.

Thank you czarivey.  The link you provided is does't work.  So it is not a good idea to use the old solder that left on circuit board after remove resistor?  

There are some places where RadioShack is still opened. I was still wondering if the place 15 miles away from my home in north of Durham NC is still the only one active RadioShack in the world!
They sold similar model to this one and that's the one I use professionally. 
http://http//www.parts-express.com/ecg-j-045-ds-45-watt-desoldering-iron--372-202
Desoldering pump is important because of an idea of removing old solder and replace it by new. Have flux ready as well to make sure that solder fills up and clean the surfaces before soldering back.