View Full Version : Signal Analysis and Processing of Computer Generated Hardware Failure Codes.

08-24-2009, 09:31 PM
Welcome to PC Signet.

In the beginning personal computers alerted the technically savvy to possible failure situations by beep codes played through the systems speaker. A short beep indicated a "0" and a long beep represented the digital equivalent of a binary "1".
So a computer might emit a lengthy musical trail of woe and sorrow equivalent to a 'My Simon' electronic touch game, or a precambrian speak & spell. Unfortunately most of us don't comprehend speech in musical tones representing digitally encoded information.
So... Time passes, technology advances, and the modus operandi shifts into the spectrum of light. light emitting diodes that is... More modern computers and laptops display their problem codes through flashing LED's on the computer itself.
Usually it is the power button. A short flash of light is a zero, and a long flash of light is a 1. So for example... SSLSSLSS means 00100100. Naturally it's not that simple... Because error messages are reverse encoded, we have to reverse it... so... 00100100 becomes 00100100. This particular example is a binary palindrome, it's the same either way. But take for example if you had SSLSSLSL, which would be 00100101 and then reversing it would give us 10100100. Ok... so far so good. Now we must convert the reversed binary to a hex code, so that we can look it up in the computers hex code list of blinking led problems...
So open windows calculator program, change the view to scientific, click binary, type in 10100100, then click hex. This gives you the hex code A4. Now google for the computer make & model, and find the technical manual, or call the maker, and ask them what hex code A4 means.
Dell & Toshiba use this, and so do a lot of other manufacturers, even sony. In fact they are using it on a wide variety of electronics including tv's and monitors. How do I know if this will benefit me in my repair shop? Well... Is the light blinking a morse code message or not, is usually a great indicator.
Ok, so you have the error code and you know what to replace.
Now sometimes it could be the computers psu, to check that, unplug everything from the mb, and see if the light goes steady or keeps blinking. This might not be a good test if you have a psu capacitor that is slow leaking, b/c with no load at all, it might appear fine, but the instant a load hits the connectors it may blink agian, so to really check this visually, you can actually open the PSU, and see if you see a capacitor that looks like it leaked, if you do replace that for .25 cents, and you have a good psu again. But it's probably better to just replace the entire psu, b/c you never know how long it's been in operation.
So... Blinking lights can mean many many things, not just a bad psu... It could indicate ram failure, bad motherboard, hard disk issues even.

08-25-2009, 12:28 AM
Very interesting and useful tip. Makes me wonder how many who recently have joined the forums know what "hex" or "hexiidecimal" means (hint: remember your A+ courses?) Good on ya! :P.