Gah, put this calculator kit together, (same one as mnementh did) and popped the batteries in, the LCD backlight came on, but the calculator refused to switch on
![Banging Head |O](https://www.eevblog.com/forum/Smileys/default/bangheadonwall.gif.pagespeed.ce.8iLbFYV4Bc.gif)
Back to basics, double-checked my work, and it was all correct so measured voltages and discovered that the regulator, 7550A-1 in TO-92 package was only giving out 3V instead of 5V, so I had a chat with Amazon customer support. Explained that I had this kit, assembled it and told them that the 5V regulator was only providing 3V, thinking that they might just send out another kit, so I can swap out the part, but nope. Sent me prepaid returns label and even though it was a kit, going to give me a full refund for it once they receive it back. So, for that I give Amazon full marks. I don't think that I'll bother re-ordering it though, I did a bit of research, and it seems that others have had similar issues with the kit and for that reason, I'll give it a miss.
![Face Palm :palm:](https://www.eevblog.com/forum/Smileys/default/xfacepalm.gif.pagespeed.ic.EBDwh1hCfo.png)
The PCB seems to nicely silk-screened and of good quality just a shame that the components aren't of equal quality. Instructions are not supplied with the kit
![WTF? :wtf:](https://www.eevblog.com/forum/Smileys/default/wtf2.gif.pagespeed.ce.pxLiY5pjs4.gif)
but they are downloadable are adequate for the job as long as you can follow the pictures OK as there is no written description.