Hi, I'm attempting a self sourced build, i'm new to electronics, so i'm a bit out of my depth here. This is my first project aside from repairing an lcd monitor by replacing bad caps on the power board (which was a success btw
Now i've been following the guide here: http://www.ladyada.net/make/x0xb0x/fab/powersupply.html
and everything was going great up until the point where you install the IC22
. Instead of getting 5.333v I am getting 11.15v. The trimpot does seem to work, but obviously doesn't have the range to get me down to 5.333v, lol. I continued to the next step in the guide to see what happened and so i've installed the 6562 (IC23
) and tested the voltages. Once again, for the '5.333v' I am getting over 11.15v. I then tested the '+12v' supply and get a reading of 24.5v. So i'm getting roughly twice the voltage that I should be. I've checked the resistor ratings and the caps to make sure I used the right ones. I checked the diode orientation, the ic orientation, all seems fine. I've tested my ac 9v power supply and it puts out 11.3v which should be fine right? So I'm low on ideas.
Three things I would like to mention, in case they may be part of the problem:
#1. I had a go at soldering the usb chip, and stuffed it up, it is currently attached to the board, but with several pins bridged, I have been unable to remove it. I have been working on the assumption that its presence on the board won't affect 5.333v and 12v supplies (please tell me if I'm mistaken). I was planning to go back to the usb chip later on to see what I can do with it, but I thought I better mention it in case it's responsible for the problem here.
#2. I placed a 202 trim pot and then later I acquired a different one which I liked more (a Vishay CT6EP202 as per the bill of materials. I was unsure of the suitability of the other pot I had, so I thought i'd play it safe and get the one in the bom), so I desoldered the old one. This proved challenging and I had to mutilate the old one in the process, but I managed to remove it (in retrospect I should have stuck with the first one). I am mentioning this because I guess it is possible that I damaged the pcb in the process of doing this. The new pot does seem to function, it affects the voltage as I'd expect it to, but for all I know, it could still be the source of the problem.
#3. Some of my 5% resistors are blue metal film rresistors rather than the usual carbon film, which I ordered by mistake. From what I can tell, this will make zero difference, but I'm mentioning it just in case.
Thanks in advance for helping.