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<div dir="ltr" data-setdir="false">How did you get on with the soldering ?<br></div><div><br></div>
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On Saturday, 19 March 2022, 20:30:57 GMT, James Dutton via Wolves <wolves@mailman.lug.org.uk> wrote:
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<div><div id="ydpb4a45e11yiv3733007900"><div><div dir="ltr"><div class="ydpb4a45e11yiv3733007900gmail_quote"><div dir="ltr" class="ydpb4a45e11yiv3733007900gmail_attr">On Sat, 19 Mar 2022 at 19:34, Chris Ellis via Wolves <<a shape="rect" href="mailto:wolves@mailman.lug.org.uk" rel="nofollow" target="_blank">wolves@mailman.lug.org.uk</a>> wrote:<br clear="none"></div><blockquote style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex;" class="ydpb4a45e11yiv3733007900gmail_quote">Hi James<br clear="none">
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On Sat, Mar 19, 2022 at 2:52 PM James Dutton via Wolves<br clear="none">
<<a shape="rect" href="mailto:wolves@mailman.lug.org.uk" rel="nofollow" target="_blank">wolves@mailman.lug.org.uk</a>> wrote:<br clear="none">
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> Hi,<br clear="none">
><br clear="none">
> I know this is not Linux, but I know some people on this list play with electronics.<br clear="none">
> I have a component I wish to replace on a PCB.<br clear="none">
> NCP1250<br clear="none">
> It is a TSOP−6 package about 1.5 x 3 mm. It is a chip with 6 pins.<br clear="none">
><br clear="none">
> I have not done surface mount stuff before.<br clear="none">
><br clear="none">
> As it is so small, what do people suggest as options for going about doing it?<br clear="none">
<br clear="none">
That should be pretty manageable with just a standard soldering iron.<br clear="none">
<br clear="none">
The general trick with SMT hand iron work is rather counter-intuitive,<br clear="none">
basically be messy and then clean up. Desoldering braid and some flux<br clear="none">
paste is very essential.<br clear="none">
<br clear="none">
Essentially, tack one lead into place to align it. Then drag a solder<br clear="none">
ball over the pins, don't worry about bridges. Then clean up with the<br clear="none">
desoldering braid. Volia a clean looking SMT joint.<br clear="none">
<br clear="none">
The other option is to buy a hot air SMD rework station, you should be<br clear="none">
able to get one on Ebay/Amazon for ~£30ish (tend to go by the name<br clear="none">
858D). You can use this to reflow just the specific parts. Easy to<br clear="none">
remove the part.<br clear="none">
Then add solder to each pad with an iron, cover in flux and use the<br clear="none">
hot air to reflow.<br clear="none">
</blockquote><br clear="none"><div>Hi Chris,</div><div><br clear="none"></div><div>Thank you very much for the advice and tips.<br clear="none"></div><div>I have not needed or used a desoldering braid before.</div><div>I have a heat gun (blower) but I think it is more suitable for plumbing than PCBs, It has wide nozzles that would heat the whole PCB!!! <br clear="none"></div><div>I was wondering how to do just one chip at a time so thank you for pointing me towards the 858D.</div><div><br clear="none"></div><div>I am going to purchase some braid and the 858D before I continue.</div><div><br clear="none"></div><div>I had already replaced the triac, because it was an obvious short, but it did not fix the PSU.</div><div>I have then removed some components to test them, and the rest I have tested in place.</div><div>As it turns out, all the components that have lost their labels are faulty, so it is turning out to be quite easy to fault find, if I was starting again from new, I would just check the ones with damaged labels!!!</div><div>It seems that SMT resistors are failing to become open circuit, and all the transistors/triacs fail to become shorts.</div><div>Is that a general rule for SMT resistors, or are they specific to this PCB ?</div><div><br clear="none"></div><div>It has been fun finding out about SMT. For example, in my testing I found a few components that appeared to be shorts, but on further investigation I found out what a label of "0" means, :-)</div><div>In a through hole, one just uses a bit of wire, but for SMT, one uses actual components that look like resistors.</div><div><br clear="none"></div><div>In case it helps others. With mains voltage and SMPS (PSU) , the voltage can be 340 Volts. But as the front end of the circuit is a rectifier, one can do all the testing with a 12V DC or 48V DC supply and the PSU should still function fine, and one can test with non-dangerous voltages. It does not necessarily provide the full amps at the output when you have it working, but it is much safer to work with and diagnose.<br clear="none"></div><div><br clear="none"></div><div>Kind Regards</div><div id="ydpb4a45e11yiv3733007900yqtfd93412" class="ydpb4a45e11yiv3733007900yqt1040742513"><div><br clear="none"></div><div>James</div><div><br clear="none"></div><div><br clear="none"></div><div><br clear="none"></div><div><br clear="none"></div><div><br clear="none"></div><div><br clear="none"></div><div><br clear="none"></div><div><br clear="none"></div><div><br clear="none"></div><div><br clear="none"></div><div><br clear="none"></div><div><br clear="none"></div><div><br clear="none"></div><div><br clear="none"></div><div>Kind Regards</div><div><br clear="none"></div><div>James</div><div><br clear="none"></div><div><br clear="none"></div><div><br clear="none"></div><div><br clear="none"></div><div><br clear="none"></div></div></div></div><div id="ydpb4a45e11yiv3733007900yqtfd12923" class="ydpb4a45e11yiv3733007900yqt1040742513">
</div></div></div><div class="ydpb4a45e11yqt1040742513" id="ydpb4a45e11yqtfd28738">-- <br clear="none">Wolves LUG mailing list<br clear="none">Homepage: <a shape="rect" href="http://www.wolveslug.org.uk/" rel="nofollow" target="_blank">http://www.wolveslug.org.uk/</a><br clear="none">Mailing list: <a shape="rect" href="mailto:Wolves@mailman.lug.org.uk" rel="nofollow" target="_blank">Wolves@mailman.lug.org.uk</a><br clear="none">Mailing list home: <a shape="rect" href="https://mailman.lug.org.uk/mailman/listinfo/wolves" rel="nofollow" target="_blank">https://mailman.lug.org.uk/mailman/listinfo/wolves</a><br clear="none"></div></div>
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