re-soldering dry joints in old hi-fi amp

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downonthestreet

New member
Not sure if this question is appropriate in this section, or even on this BB, but let's see...

I have an old but good quality Sony hifi amp - was once top of the line. The attenuator pots and balance pots now need replacing, as they are noisy, and I have been told that most of the joints are dry and need resoldering. Have been quoted more than the amp is now worth to do these repairs.

I have no experience whatever in electronics, but am wondering how difficult it might be to do these repairs myself. Is re-soldering the dry joints a job for an expert, or just a bit painstaking? Any special equipment required?

NOTE: I wouldn't even know what a dry joint - or any joint - actually looked like, but I didn't know anything about car engines, either, and managed to tune up my car for 15 years after a few minutes of hands-on instruction from someone who knew what they were doing (I took notes). Never did undestand how the engine worked, or why I was adjusting the dwell angle, setting the carbie as I was taught etc, and the tuning up still got the engine purring!

Wondering if it is realistic to learn about repairing my amp from someone who knows their stuff, or is it a job that can't be learned overnight and should not be attempted by someone without an initial clue?

Cheers
 
downonthestreet said:
I have an old but good quality Sony hifi amp - was once top of the line. The attenuator pots and balance pots now need replacing, as they are noisy, and I have been told that most of the joints are dry and need resoldering.
Click to expand...

Street,

Not what we usually deal with here - but will give it a shot.

I'm confused a bit by what I'm seeing you've been told.

A "dry joint" is generally describe as follows:

When the temperature is insufficient, there will be a layer of solid solder beneath the melted solder and amalgamation will not take place. Such poorly made joints are called "dry joints" and are a common cause of electrical faults.

This is (therefore) something that occurs at the point of soldering the joint - but shouldn't be able to occur with a joint that was properly soldered.

However - to answer your question - I don't do a lot of soldering - but when it do it's nice, clean - and not all that difficult. The trick is just to practice first -

Heres a link that will explain the basics to you -

http://www.users.globalnet.co.uk/~bunce/solderit.htm#Top

Pick up a good quality iron - some scrap wire - and practice for a while - you can also pick up some boards and components at Radio Shack and practice on those as well - once you have it down smoothly (and it shouldn't take you all that long) you should be able to do what you want.

SIncerely,

Rod
 
I've been through this before with vintage, analog recording gear.

What happens is the solder joints were perfect 30+ years ago, and through age, corrosion, moisture exposure, wild temperature changes etc, the solder joints seem to weaken and of course, allow corrosion on the solder lugs, component tabs, and of course the wire ends themselves.

The way to fix this is easy. Touch your heated soldering iron to the joint, using a cheap bulb-style solder sucker to remove the bulk of the solder. Shiney stuff will be left behind which is fine. Then resolder the joint.

When I was redoing all the joints in my old B3 (which is a lot of resoldering mind you), I made a super-solder-sucker to make the job quicker. I have a very small 1 gallon shop vac, and in the end of the hose I shoved a rubber stopper I drilled a 1/4" hole through, which I pushed a glass eyedropper (without the bulb on top of course) through, and desoldered with that.

You've never seen bad solder disappear so quickly!
 
frederic said:
I've been through this before with vintage, analog recording gear.

What happens is the solder joints were perfect 30+ years ago, and through age, corrosion, moisture exposure, wild temperature changes etc, the solder joints seem to weaken and of course, allow corrosion on the solder lugs, component tabs, and of course the wire ends themselves.

The way to fix this is easy. Touch your heated soldering iron to the joint, using a cheap bulb-style solder sucker to remove the bulk of the solder. Shiney stuff will be left behind which is fine. Then resolder the joint.
Click to expand...

Good to see frederic is still around, and telling like it is. DITTO!
 
frederic said:
I'm still around. I just have less free time than I used to.

New Munchkins will do that yanno :)
Click to expand...

I know what ya mean, my son turns 1 on Dec 5th and he takes A LOT of my time. :)
 
My son is 7 months, 2 days. He sits up, crawls forward and backwards, and if he's near the sofa, coffee table, TV stand or the high chair, he pulls himself up to a standing position and holds on.

Since I'm not working at the moment, my wife and I take turns with "baby duty", so each of us can have a few hours of free time a day. Unfortunately, most of my free time is spent fixing things around the house, fixing automobiles, and what little of that time is leftover, I spend working on my project truck.

So, my studio is a bit dusty. Once the temps regularly hit below 40 during the day, truck project season is over and I'll resume having minimal free time, but spend it in my nice warm, well insulated recording studio.

Probably spending it soldering the patch bays I've not gotten around to...
 
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