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Vladimir Ivanovich Kirillov
Prolific User
Username: soviet

Post Number: 1618
Registered: 02-2013
Posted on Saturday, 07 September, 2019 - 09:47:   Edit PostDelete PostView Post/Check IP

Quite sometime back I sent the Mad Scot away with my Pioneer amplifier to a nearby city to have it repaired and then I made the mistake of paying $300 to have it repaired and it came back not repaired.

When you switch it on sometimes it lights up the display which indicates it's ready to pump and other times the display won't light up which means it won't play.

Just an aside, the Mad Scot informed me the repairer is one of those idiots who yaps on and on about God ...I wish I knew that before because I have a pathological propensity to avoid churchy nutbags like the bubonic plague.

My first thought of course was to help the repairer work out the difference between low grade theology, amplifier repair and his front teeth but sadly Australia is a place where this useless scum are a protected species.

So I attempted the repair myself and stuffed it royally. Behind the main on off switch was a small white plug with three wires and I decided to pull it off and clean the contacts with electrical contact cleaner before going nuts with the multimeter to track down this annoying intermittent fault.

Big mistake. It was no plug. It looked like a plug but hidden from sight was three copper bent pin contacts which do a 90 degree turn and then go into a small circuit board. A Japanese trap for certain.

Question. How do you resoldier something so small without overheating the circuit board?

Lesson and moral: When you send something to get repaired by a specialist go personally to the business and before you pay a kopeck for the repair demand a demonstration that the bloody thing has been repaired.

If it does not work lean to one side and come down hard with your elbow lightning fast Bruce Lee style straight into the repairer's eye socket.

Sorry mate, I slipped are you okay. Gosh you've got a hard skull I think I have broken a bone in my elbow, ouch it hurts. Gather "repaired" item and leave naturally without paying.
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Brian Vogel
Grand Master
Username: guyslp

Post Number: 2957
Registered: 06-2009
Posted on Saturday, 07 September, 2019 - 11:17:   Edit PostDelete PostView Post/Check IP

Generally, a 30W electric iron is pretty darned safe for soldering PCBs. Here is a really inexpensive one that you can adjust between 20W and 60W and that has the tips you would need: Wmore Soldering Iron Kit.

There are also micro-torches with soldering attachments that can be used if one is capable of sufficient speed, which I am not.

There are so many tutorials on PCB soldering and desoldering out there that it would be useless for me to say anything about the subject that has not already been said.

Brian, who's actually used a regular 100W iron on one or two occasions, when I was young, stupid, and in a desperate hurry. Never killed a any of the electronics, either [probably dumb luck]
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Vladimir Ivanovich Kirillov
Prolific User
Username: soviet

Post Number: 1619
Registered: 02-2013
Posted on Saturday, 07 September, 2019 - 12:12:   Edit PostDelete PostView Post/Check IP

Brian does PCB mean power circuit board? Thanks for your kind advice Brian, I thought you would know the answer and as usual you never disappoint.

Hard to gather you were ever stupid Brian.}
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Robert J. Sprauer
Frequent User
Username: wraithman

Post Number: 532
Registered: 11-2017
Posted on Saturday, 07 September, 2019 - 12:37:   Edit PostDelete PostView Post/Check IP

PCB printed circuit board.. Mini torch on a board...no way!!!
Buy a soldering station. They can be bought used and are pencil like and the heat is controlled. I use them all the time on classic audio repair for over 30 yrs. The tips can be changed
to suit the work, but usually a small pencil bought is most common.
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Brian Vogel
Grand Master
Username: guyslp

Post Number: 2958
Registered: 06-2009
Posted on Saturday, 07 September, 2019 - 13:02:   Edit PostDelete PostView Post/Check IP

Robert,

I'm not saying to use a mini-torch directly on a PCB. There are, however, plenty of "torch-based" soldering irons that are used widely in electronic work, particularly in the field where power outlets are not conveniently available.

They don't look all that much different from your typical electric solder iron and the flame is completely contained very far away from the board or actual soldering tip.

They also have the standard collection of interchangeable tips.

Brian, who uses an electric iron, but knows folks who like the "torch based" variety, too
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michael vass
Frequent User
Username: mikebentleyturbo2

Post Number: 582
Registered: 07-2015
Posted on Saturday, 07 September, 2019 - 17:43:   Edit PostDelete PostView Post/Check IP

Hi Brian , the gas powered ones use a catalyst not a flame, if I understand you OK
Mikr
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ross kowalski
Prolific User
Username: cdfpw

Post Number: 1220
Registered: 11-2015
Posted on Saturday, 07 September, 2019 - 21:18:   Edit PostDelete PostView Post/Check IP

Vlad,

Remove previous solder on the pads, Clean the pads well, tin the pads, use 63/37 rosen, hold the tip to each component leg first then the pad, have a well tinned soldering iron tip.

Make sure the soldering iron is fully up to temp and have it firmly against the component leg to get the heat in fast. A switch leg should solder in moments, not 15 seconds. 15 second type times is how boards get damaged.

And most importantly, practice on some cheap electronic device first. Soldering is a lot like welding good preparation and subtle moves.

Luck.
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Vladimir Ivanovich Kirillov
Prolific User
Username: soviet

Post Number: 1620
Registered: 02-2013
Posted on Saturday, 07 September, 2019 - 21:33:   Edit PostDelete PostView Post/Check IP

Ross I have done plenty of soldering but nothing on anything so small.

The plug looking thing has three bent pins coming out of it that are 1/4 inch at the most across all three pins. The pins are less than one millimeter diameter thick. I can see no solder on either side of the small circuit board where they go into place.

Ross what is a pad?
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ross kowalski
Prolific User
Username: cdfpw

Post Number: 1221
Registered: 11-2015
Posted on Sunday, 08 September, 2019 - 01:41:   Edit PostDelete PostView Post/Check IP

Vlad,

Pads are round areas at the end of the tracings on the PCB. They are bigger to allow solder some surface to attach to.

If you don't see solder, perhaps it's on the other side of the board.

Can you take a close up picture?
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ross kowalski
Prolific User
Username: cdfpw

Post Number: 1222
Registered: 11-2015
Posted on Sunday, 08 September, 2019 - 01:49:   Edit PostDelete PostView Post/Check IP

Also,

Looking at your original post. A word about reworking / repairing a finished board. Most boards are green because they are coveted with an insulating glyptol layer.

Solder does not stick to glyptol so if you have three pins that are smaller than your soldering pencil's tip you are still OK.

Put the component in place with flux, heat it until the three pins are soldered but also bridged (one blob of solder joining all three pins,) then wick away the extra solder with some solder removing wick.
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ross kowalski
Prolific User
Username: cdfpw

Post Number: 1223
Registered: 11-2015
Posted on Sunday, 08 September, 2019 - 01:55:   Edit PostDelete PostView Post/Check IP

Vlad,

If there are truely no surface "wires" tracings from the holes where the plug gets soldered on then it's a little more complicated.

See if you can get a picture.
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Mike Thompson
Frequent User
Username: vroomrr

Post Number: 942
Registered: 04-2019
Posted on Sunday, 08 September, 2019 - 04:08:   Edit PostDelete PostView Post/Check IP

There used to be real repair men that you took electrical stuff to and they could/would repair them. Now the way things are built, you just either throw it away or put in a whole new board. Especially with computers (and phones). As a computer tech I would trace down the component that was bad and replace it. It was way cheaper than trying to fix that component. You might be able to buy that board cheaper than to try to fix it.

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