Desolder and Solder in of an STK391-020 Conversion IC From ZenithProjection TV

[VoRTeX]

Im just asking what power soldering iron I should use for this job, is a 20w iron sufficient? What precautions should I take to ensure i dont mess up the new IC circuit (by burning it up) .If this job is just a standard job that needs no other precautions than listed in the FAQ then let me know. Im just curious how hard it is to burn something up doing this. Thanks


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[Arfa Daily]

Im just asking what power soldering iron I should use for this job, is a
20w iron sufficient? What precautions should I take to ensure i dont mess
up the new IC circuit (by burning it up) .If this job is just a standard
job that needs no other precautions than listed in the FAQ then let me
know. Im just curious how hard it is to burn something up doing this.
Thanks


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------= Binary Usenet downloading made easy =---------
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I replace these hybrids all the time using a standard Weller TCP series 50
watt magnastat iron. I've never had a problem. The trick is to get the old
one out cleanly, without damaging the print. Run new solder onto the old
joints first. Then remove the old solder using a solder sucker or desolder
braid. When you've got the old hybrid out, clean all of the old paste from
the heatsink, then put a thin layer of new paste on the back of the new
hybrid. Feed the legs carefully into the PCB holes, and make sure that
they've all gone through properly. There's nothing worse than getting 3
joints from the end, and finding that a leg has twisted up behind a
resistor, where you can't get at it ...

Screw the device to the heatsink, before soldering. Make each joint
reasonably quickly ; 2-3 seconds is fine. You shouldn't then have a problem.

If it doesn't work when you've done the job, check for any low value feed
resistors on the supply rails being open.

Arfa

 

[n cook]

Im just asking what power soldering iron I should use for this job, is a

20w iron sufficient? What precautions should I take to ensure i dont mess up
the new IC circuit (by burning it up) .If this job is just a standard job
that needs no other precautions than listed in the FAQ then let me know. Im
just curious how hard it is to burn something up doing this. Thanks

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------= Binary Usenet downloading made easy =---------
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Only yesterday I used a hot air gun to desolder such a hybrid output device,
no dislodged tracks, didn't even have to clean up the holes afterwards.
Clean,quick, easy and cheap and a tool with multiple uses , unlike a
de-solder tool.

 

[Arfa Daily]

20w iron sufficient? What precautions should I take to ensure i dont mess
up
the new IC circuit (by burning it up) .If this job is just a standard job
that needs no other precautions than listed in the FAQ then let me know.
Im
just curious how hard it is to burn something up doing this. Thanks

Only yesterday I used a hot air gun to desolder such a hybrid output
device,
no dislodged tracks, didn't even have to clean up the holes afterwards.
Clean,quick, easy and cheap and a tool with multiple uses , unlike a
de-solder tool.

Good for those of us " in the trade ", but I'm always reluctant to recommend
it to 'have a go' interested non professionals ... d;~}

Arfa

 

[n cook]

Good for those of us " in the trade ", but I'm always reluctant to recommend
it to 'have a go' interested non professionals ... d;~}

Arfa

I find it a bit galling that I own a proper vacuum pump assist desolder
station and a more basic blug in a Weller base hand vacuum one but rarely
use either.
Hot air gun is so much more efficient and less colateral damage, lifted
tracks etc, even for desoldering SM ICs after shrouding off surrounding
comps.

 

[Arfa Daily]

I find it a bit galling that I own a proper vacuum pump assist desolder
station and a more basic blug in a Weller base hand vacuum one but rarely
use either.
Hot air gun is so much more efficient and less colateral damage, lifted
tracks etc, even for desoldering SM ICs after shrouding off surrounding
comps.

That's the trick to it, though - masking off surrounding components, and
making sure that there's no plastic nearby ...

I also have a Weller vacuum desolder station that I use on a daily basis for
general work, and twice or so a week on large batch commercial board repair
work, and I have to say that it is absolutely excellent at the job, and I
have never damaged any print with it. The only thing that I would say is
that it needs 10 minutes a week spent on maintenance - cleaning and
replacing filters, cleaning out the solder channels and receiver glass etc,
and as soon as the nozzle starts to become tight at getting the cleaning
wire into, it's time to replace it. I have to fit new O rings to the
receiving glass about every three or four months, and about once a year, I
strip the vacuum pump, and clean or if necessary replace the flap valves,
and clean out the vacuum pipes, that get flux fume residue in them, even
though the vacuum system is filtered.

Arfa

 

[[email protected]]

Only yesterday I used a hot air gun to desolder such a hybrid output device. . .

Tell me more about this. In my profound ignorance, I've never
heard of such. I would like to know the device, and the procedure.
Thank you.

David, on the Illinois prairie.

 

[n cook]

device. . .


Tell me more about this. In my profound ignorance, I've never
heard of such. I would like to know the device, and the procedure.
Thank you.

David, on the Illinois prairie.

Scroll down to the 2 hints and tips files on the URL below

 

[Smitty Two]

I also have a Weller vacuum desolder station that I use on a daily basis for
general work, and twice or so a week on large batch commercial board repair
work, and I have to say that it is absolutely excellent at the job, and I
have never damaged any print with it. The only thing that I would say is
that it needs 10 minutes a week spent on maintenance - cleaning and
replacing filters, cleaning out the solder channels and receiver glass etc,
and as soon as the nozzle starts to become tight at getting the cleaning
wire into, it's time to replace it. I have to fit new O rings to the
receiving glass about every three or four months, and about once a year, I
strip the vacuum pump, and clean or if necessary replace the flap valves,
and clean out the vacuum pipes, that get flux fume residue in them, even
though the vacuum system is filtered.

Arfa

That's darn good advice. My sucker works like magic when I take care of
it, and like a worthless piece of s--t when I don't.

 

[Smitty Two]

Im just asking what power soldering iron I should use for this job, is a 20w
iron sufficient? What precautions should I take to ensure i dont mess up the
new IC circuit (by burning it up) .If this job is just a standard job that
needs no other precautions than listed in the FAQ then let me know. Im just
curious how hard it is to burn something up doing this. Thanks


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I don't know what the FAQs say, but this is the way I would do it:

Use a temperature controlled iron with a *new* shiny tip. Use liquid
flux. I agree with Arfa that the hot air gun is not for the novice. Easy
and effective, it still requires practice, and general as well as
"application specific" precautions.

If the old IC is to be discarded, use a *very* sharp, small-nosed, *full
flush* diagonal cutter to cut the legs from the body of the IC. Then dot
each leg with flux, and pull them off the board with the soldering iron.

Wick residual solder from the pads so the new IC will sit flat.

Crank the temp up to at least 700. 800 is fine, too. Hold the IC down
with a stick, put flux on the joints, melt a little solder on the tip of
the iron, and touch to each joint.

You should be able to solder each leg in far less than one second. If
not, something is wrong with the equipment or the technique.

 

[Arfa Daily]

I don't know what the FAQs say, but this is the way I would do it:

Use a temperature controlled iron with a *new* shiny tip. Use liquid
flux. I agree with Arfa that the hot air gun is not for the novice. Easy
and effective, it still requires practice, and general as well as
"application specific" precautions.

If the old IC is to be discarded, use a *very* sharp, small-nosed, *full
flush* diagonal cutter to cut the legs from the body of the IC. Then dot
each leg with flux, and pull them off the board with the soldering iron.

Wick residual solder from the pads so the new IC will sit flat.

Crank the temp up to at least 700. 800 is fine, too. Hold the IC down
with a stick, put flux on the joints, melt a little solder on the tip of
the iron, and touch to each joint.

You should be able to solder each leg in far less than one second. If
not, something is wrong with the equipment or the technique.

Hey Smitty, how's it going ?

The IC in question isn't a surface mounter - it's one of those gi-normous
output hybrids with a single line of through-the-board pins, so normal
through board removal techniques are all that's required ( after first
splatting some liquid flux on, of course ... d;~} )

Arfa

 

[Smitty Two]

Hey Smitty, how's it going ?

The IC in question isn't a surface mounter - it's one of those gi-normous
output hybrids with a single line of through-the-board pins, so normal
through board removal techniques are all that's required

Ah, thanks Arfa. I mis-inferred from some other response that it was a
surface mount.

 

[Lionel]

Im just asking what power soldering iron I should use for this job, is a 20w iron sufficient?

Not even close. If you /must/ desolder the original chip, you should
use a professional station (eg; Weller TCP) with a heavy tip. But it's
easier & quicker to snip the legs away from the body of the failed
chip & remove them one by one with an iron & a pair of tweezers.

Once you've done the above & cleaned up the holes + pads, soldering in
the new part is pretty straightforward.