What a Busted Lenovo Taught Me About _____________
(and maybe my artwork)
“Motherboard repair isn’t supposed to be done this way” I thought to myself while repeatedly removing one component after another with my hot-air station then re-testing the short-circuit with my trusty multimeter. With each test I heard the overly familiar B-E-E-P to let me know that I hadn’t found the cause of the problem yet. This process was frustrating. After all, I had already found and removed the blown inductor, but I was still trying to work my way through the many circuits inside a laptop motherboard to figure out why it blew up in the first place. I knew this wasn’t the most practical approach to solving the mystery, but still embracing the opportunity to learn.
My troubleshooting steps felt wrong. I’ve watched enough YouTube repair videos from Louis Rossmann and Jessa Jones to know that injecting power into the suspect circuit would result in the bad component heating up enough to boil-off rubbing alcohol, melt frost from a can of compressed air, or violently fail in a fiery blaze of glory, in all cases revealing itself to me for replacement. I couldn’t do this though. No, the DC power supply that I ordered through eBay (because I don’t have an extra thousand dollars just sitting around), [which I thought was needed before doing quick research for this paragraph], arrived and didn’t work. I mean, it turned on, which was apparently the comprehensive test the seller came up with to mark it “Tested” on the listing with a clear conscience. However, the power supply didn’t provide the necessary output to make it more useful than a VCR with 12:00 blinking incessantly. What a turd. But I digress…
This is when I turned to schematics and it took quite some time to find. Many schematics and what repair technicians call “boardview” software files usually have to “fall off the back of a truck” in order to have access to them. There are online forums for repair techs where these files can be traded around with support, and other websites where these files may have a price tag associated. Fortunately, a friendly tech from BadCaps.net shared them with me.
As I followed along the circuit diagram, testing along the way, patterns began to emerge. Three circuits in particular; U133, U134, & 136; each identical in appearance, were showing the same short-to-ground fault, all in the same places.
These circuits taunted me. They wanted me to quit. They wanted test the very bounds of my sanity.
Even more unfortunate was that each of these places ended with a network of dozens or more of capacitors where if even one dies it’s version of electrical death it makes them all appear that way, too. This is where testing started, with the remove-and-test strategy ad nauseam. Now I was seeing a pattern repeat across circuits. Where did they go? Where did they converge? Why can’t my damn DC power supply work? Ugh…