0
\$\begingroup\$

I installed the socket for a NE555 timer ic backwards on a PCB. Can I just reverse the chip in the socket to cure the mistake?

\$\endgroup\$
  • 1
    \$\begingroup\$ you can put the chip in the right way round... for the board... the socket being backwards is irrelevant. Assuming "Socket" means what I think it means.... \$\endgroup\$ – Trevor_G Dec 28 '17 at 21:49
  • 1
    \$\begingroup\$ If you put it on the wrong side of the PCB, that's a problem. \$\endgroup\$ – Brian Drummond Dec 28 '17 at 22:07
  • 1
    \$\begingroup\$ Does your PCB have markings to indicate which corner is pin 1? I would always rely on a PCB's markings before a socket's markings. \$\endgroup\$ – Harper Dec 28 '17 at 23:02
  • \$\begingroup\$ what makes you think that the socket is "backwards" ? \$\endgroup\$ – jsotola Dec 29 '17 at 6:03
  • \$\begingroup\$ I'm new at this and forgot to check the orientation of the picture on the PCB. So I put it in with the markings facing the wrong way. \$\endgroup\$ – WebUserLearner Dec 29 '17 at 22:40
2
\$\begingroup\$

So long as the IC pins connect to the right PCB tracks, the orientation of the IC socket is irrelevant.

Look at where pin 1 of your 555 IC is and make sure it's connected to the pin 1 solder pad.

\$\endgroup\$
4
\$\begingroup\$

The real question is why you'd use a socket for a cheap IC like a 666 555 timer, or why you'd even use a thru hole part in the first place, but I digress.

OK, closing my eyes and trying to imagine back to the Pleistocene.

It depends on what you mean by "backwards". If you simply started counting pin 1 in the wrong corner, then all you have to do is rotate the chip.

If you actually mirror-imaged the footprint, it can still be done, although it's a bit more tricky. Basically, you bend all the legs 180°. That's conceptually easy, but the trick is to not break them off in the process. Do it right so you only need to bend them once. Use a flat screw driver or something to bend each leg the other way right where it comes out of the package.

It's probably a good idea to somehow mark the pin 1 corner on what used to be the bottom of the chip but is now the top. That avoids the next thing you'll do wrong, which is to plug in the flipped chip rotated.

Another trick for a mirrored footprint is to mount the unmodified chip on the bottom of the board instead of the top.

Back to your regularly scheduled time and place.

\$\endgroup\$
  • 1
    \$\begingroup\$ To your first paragraph questions, presumably because there's untold mountains of example circuits to learn from and explore and because through-hole is dead easy for learners while surface mount is a nightmare - c'mon, you know all that :-) \$\endgroup\$ – TonyM Dec 28 '17 at 21:58
  • 1
    \$\begingroup\$ @Tony: No, thru-hole isn't easier, it's only thought to be easier by those who haven't actually used surface mount parts. SMD parts are much easier and faster to solder. No sticking the leads thru holes, bending them so the part doesn't fall out when you flip the board to solder the bottom, etc. Yucc. I gladly left those experiences in the 1990s. \$\endgroup\$ – Olin Lathrop Dec 28 '17 at 22:01
  • 3
    \$\begingroup\$ lol Not when your blind as a bat like me it isn't... ;D \$\endgroup\$ – Trevor_G Dec 28 '17 at 22:02
  • 2
    \$\begingroup\$ Not for a teenager in their bedroom with a £15 iron and a pair of tweezers, though sir. You're dead right for us with the luxury of wealthy equipment and bone-aching experience but then we don't visit this site to ask those first footstep questions :-) \$\endgroup\$ – TonyM Dec 28 '17 at 22:15
  • 3
    \$\begingroup\$ Learning curve is shallower for thru holes. I broke a USB plug off an external hard drive and the repair is not one I look forward to. \$\endgroup\$ – Harper Dec 28 '17 at 23:04
1
\$\begingroup\$

You might, given a DIP 555, carefully bend the 8 leads the opposite way, and insert into the socket.

\$\endgroup\$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.