hey guys,

I need to remove a sub-miniature audio transformer from a PCB. It should
be a piece of cake and always has been in the past, but something's
different about this one. At those odd times previously when I've done
this, I've just used a soldering iron and a vacuum pump to melt the
joints and suck off the solder. The pins are then free and the part
almost drops off by itself.
This one is not so simple, though. It's a double-layer board and the
transformer is mounted directly on top of the traces that feed it. On the
reverse side, I can see the end of the transformer's leads poking through
just proud of where a pad would normally be, but in this case, there are
no pads 'cos there are no traces; just tiny, isolated circles of solder
around each lead-end. I guess I need to get at the actual solder joints
proper on the top side, but the transformer is sat right on top of them
making it totally impossible to even see the joints I need to get at! Whut
gives here? Are these things deliberately designed to be unserviceable
nowadays? Is that the idea? ******* manufacturers want us to buy new
stuff instead of fixing old?
Sigh. Does anyone know a ruse to defeat this darstardly scam?

"Julian Barnes" wrote in message
...
hey guys,

I need to remove a sub-miniature audio transformer from a PCB. It should
be a piece of cake and always has been in the past, but something's
different about this one. At those odd times previously when I've done
this, I've just used a soldering iron and a vacuum pump to melt the
joints and suck off the solder. The pins are then free and the part
almost drops off by itself.
This one is not so simple, though. It's a double-layer board and the
transformer is mounted directly on top of the traces that feed it. On the
reverse side, I can see the end of the transformer's leads poking through
just proud of where a pad would normally be, but in this case, there are
no pads 'cos there are no traces; just tiny, isolated circles of solder
around each lead-end. I guess I need to get at the actual solder joints
proper on the top side, but the transformer is sat right on top of them
making it totally impossible to even see the joints I need to get at! Whut
gives here? Are these things deliberately designed to be unserviceable
nowadays? Is that the idea? ******* manufacturers want us to buy new
stuff instead of fixing old?
Sigh. Does anyone know a ruse to defeat this darstardly scam?

Hot air desoldering tool.

This one works nice:

http://www.ebay.com/itm/281501377815...%3AMEBIDX%3AIT

Consider adding ChipQuick to lower the melting point.

http://www.ebay.com/itm/CyberDoc-CHI...AOSwPgxVLEk M

And flux.

On 26/02/2016 19:08, Julian Barnes wrote:
hey guys,

I need to remove a sub-miniature audio transformer from a PCB. It should
be a piece of cake and always has been in the past, but something's
different about this one. At those odd times previously when I've done
this, I've just used a soldering iron and a vacuum pump to melt the
joints and suck off the solder. The pins are then free and the part
almost drops off by itself.
This one is not so simple, though. It's a double-layer board and the
transformer is mounted directly on top of the traces that feed it. On the
reverse side, I can see the end of the transformer's leads poking through
just proud of where a pad would normally be, but in this case, there are
no pads 'cos there are no traces; just tiny, isolated circles of solder
around each lead-end. I guess I need to get at the actual solder joints
proper on the top side, but the transformer is sat right on top of them
making it totally impossible to even see the joints I need to get at! Whut
gives here? Are these things deliberately designed to be unserviceable
nowadays? Is that the idea? ******* manufacturers want us to buy new
stuff instead of fixing old?
Sigh. Does anyone know a ruse to defeat this darstardly scam?


Diamond encrusted cutting wire?

On 26/02/2016 19:28, N_Cook wrote:
On 26/02/2016 19:08, Julian Barnes wrote:
hey guys,

I need to remove a sub-miniature audio transformer from a PCB. It should
be a piece of cake and always has been in the past, but something's
different about this one. At those odd times previously when I've done
this, I've just used a soldering iron and a vacuum pump to melt the
joints and suck off the solder. The pins are then free and the part
almost drops off by itself.
This one is not so simple, though. It's a double-layer board and the
transformer is mounted directly on top of the traces that feed it. On the
reverse side, I can see the end of the transformer's leads poking through
just proud of where a pad would normally be, but in this case, there are
no pads 'cos there are no traces; just tiny, isolated circles of solder
around each lead-end. I guess I need to get at the actual solder joints
proper on the top side, but the transformer is sat right on top of them
making it totally impossible to even see the joints I need to get at!
Whut
gives here? Are these things deliberately designed to be unserviceable
nowadays? Is that the idea? ******* manufacturers want us to buy new
stuff instead of fixing old?
Sigh. Does anyone know a ruse to defeat this darstardly scam?


Diamond encrusted cutting wire?

If soldered rather than rf welded joints.
A small length of tungsten wire from a smashed 40W mains lamp, crimped
to thicker delivery wire. Varying current of a bench ps, find the
current for dull red heat of the tungsten. Drape the tungsten wire over
one of the pins , and a forcing blade/wedge in the gap while delivering
heat to that pin and repeat?

On Fri, 26 Feb 2016 19:08:33 +0000, Julian Barnes wrote:

Are these things deliberately designed
to be unserviceable nowadays?

Probably.


Is that the idea? ******* manufacturers
want us to buy new stuff instead of fixing old?

Surely.

Sigh. Does anyone know a ruse to defeat this darstardly scam?

They're a PITA - IME at any rate. This is one of the better explanations
on how to deal with them:

https://www.youtube.com/watch?v=Z38WsZFmq8E

On 27/02/2016 6:00 AM, Cursitor Doom wrote:
On Fri, 26 Feb 2016 19:08:33 +0000, Julian Barnes wrote:

Are these things deliberately designed
to be unserviceable nowadays?

Probably.


Is that the idea? ******* manufacturers
want us to buy new stuff instead of fixing old?

Surely.

Sigh. Does anyone know a ruse to defeat this darstardly scam?

They're a PITA - IME at any rate. This is one of the better explanations
on how to deal with them:

https://www.youtube.com/watch?v=Z38WsZFmq8E



The power suction jobs take some beating :-)