PC Diagnostic Methods for Techs

As Techs, we often come across the same issues multiple times, and it’s easy to start guessing and skipping the usual diagnostic methods rather than following a good diagnostic path. It’s easy to become lazy in your methods too, no matter what industry you’re in, so here’s a self evaluation checklist that can help Techs get back on track with diagnostic procedure.

Some of the steps may seem so simple and obvious, but to be frank, some ‘professional’ name brand computer shops skip over them and end up in left field trying to fix a completely unrelated issue when it was just dirty memory contacts or a faulty hard drive.

Preliminary Steps and Cautions

Always make sure you’re grounded before you open the case or enclosure. You can get a simple wrist strap with anti-static capabilities for around $10 or less with online suppliers. Maybe you’ve never used one, and you’ve never had a problem. It only takes one static discharge to ruin expensive hardware, so consider it a tiny investment that can save you thousands of dollars or more.

One of the common issues with overheating in laptops and towers is dust buildup where there shouldn’t be. So, put your mouth up to it and blow, right? You’ll be spraying moisture into the computer components, and you know what moisture will do in there. Use canned air or an air compressor that is ESD safe and has a line drier to eliminate moisture.

You don’t need too much pressure, either, as you don’t want to wear out the fan bearings or generate current with the fan motor and send a charge through the connected components. If the hard drive seems to be an issue, make a sector by sector clone of the data before doing any type of recovery work. Perform recovery work from the clone and not the original drive.

One of the first things you should do upon opening the case is check connections. Check all the cables and connectors, and check if the memory is seated firmly and securely. Plastic can often break and leave a CPU fan or other hardware hanging from it’s mounts, so check everything. Is it plugged in? Is it turned on? Are the switches good? If everything looks good inside but you’re still having issues, it’s start from the bare minimum hardware.

Bare Hardware Diagnostic Methods

The bare minimum hardware necessary to boot up is a motherboard, PSU, Processor, Memory, and a graphics card, built in display adapter, or integrated graphics capabilities. This is where you’ll want to start when you’re getting beep codes, no display, or other hardware related issues, which admittedly can be vast. If you still can’t boot, or you’re still getting beep codes or booting issues, take a closer look at the PSU first. Are there any odd smells? Sometimes a PSU that worked fine the day before can contain components that fail overnight, and leak chemicals across the circuit boards and components, and an odd smell can sometimes alert you to that.

Some PSU warranties are voided if you open up the unit, so it’s better to continue testing it with a PSU tester or a voltmeter, or just swap one out if you have a compatible power supply handy. Check each wire for the specified voltage that should be running across it, whether it’s 12v, 5v, or 3.3 volts. Depending on what the machine is used for, you may be able to substitute a lower wattage PSU, especially if the PSU that you’re replacing was high wattage but the computer didn’t have anything really requiring that much. Next, take a closer look at the motherboard for any swelling or leaking capacitors. Capacitors can still fail without any external indicators like swelling or leaking, but it’s an easy way to spot trouble visually.

If you haven’t found any issues, yet, try swapping out the memory with memory you know to be good. Try just one stick at a time in the lowest numbered available slot, and then each slot with just one stick, one at a time. Try removing all of the sticks and try booting the machine. If you get beeps now but didn’t before, the motherboard is one thing you might be able to rule out. If you weren’t getting beeps before removing the memory, and aren’t getting any after removing the memory, it’s possible the motherboard has failed. Of course, make sure you’ve got a system speaker and it’s not disabled.

On the other hand, if you’re trying to replicate an issue that happened before, and you can’t get it to happen again, check for problems with add on hardware, such as card readers, PCI cards, and other add in hardware. External hard drives and sometimes internal hard drives and optical hard drives can cause booting issues, so disconnect them all one at a time and try booting the machine.

You could even do the reverse by unplugging everything but the bare minimum hardware and plug one piece of hardware in at a time. That’s how I solved one strange issue where a card reader module had somehow shorted out and wouldn’t let the computer boot when it was plugged in. Everything booted fine until I connected the cable for the card reader, and a replacement fixed the issue. Sometimes cards get shoved in the wrong way into those card readers, and it’s not uncommon to come across damaged connectors due to that. As I mentioned before, check the memory sticks and contacts, and clean them with rubbing alcohol before reseating them.

Thermal Issues

Dust is a nuisance in some places more than others, and it can cause thermal issues when it builds up within the system, the fans, and heat sinks. Sometimes bearings wear out, thermal paste dries out, and sometimes it loses it’s effectiveness. If the machine is a few years old, you might want to remove the processor and reapply new thermal compound. The CPU has to be replaced exactly the same way it was removed, so pay close attention to the orientation.

Clean off the old thermal paste with isopropyl alcohol and a Q-tip or cotton swab, and be careful not to get it on anything else inside the case like the motherboard as the paste is conductive and can short out your hardware. An easy way to estimate how much you need is to make a small dab somewhere between the size of a grain of rice and a pea. Place it in the center of the CPU, and the pressure from the heatsink will spread it. Too much thermal compound will insulate rather than transfer heat, so be sure not to overdo it. Thermal problems can cause issues like failing components, sudden system shut down, display and interface freezing and performance throttling.

Hard Drives

When you’re troubleshooting IDE hard drives, make sure the drive jumper is set correctly and in the right position on the cable. Sometimes you’ll have to actually set it to master or slave. Sometimes cables fail too, including SATA cables, so try swapping out cables with ones you know are trustworthy. However, if you’ve got a clicking, grinding, chunking, or ticking sound, the drive has probably started to fail mechanically.

If you can still access anything on it, assess the value of the data with the owner, and let them decide if they want to let you try or use a data recovery specialist, if that’s not something you specialize in. As mentioned above, make a sector by sector clone with cloning software such as CloneZilla, and work from the clone, not the original hard drive. SMART tests are useful, but they don’t guarantee a drive is good. You might try swapping the hard drive for another that you know to be good.

When you’re doing a diagnostic on a client’s computer, be thorough, and even exhaustive. A logical, methodical approach is the most efficient way to target computer hardware issues, so avoid skipping steps thinking you might save yourself some time. Keep a detailed checklist of what you’ve checked and what you still need to check. Go back through your notes and make sure nothing has been overlooked, and you might even be able to make an earlier diagnosis based on what you’ve already checked off.

As a last tip, in most industries the buzz phrase is ‘safety first’, and as a technician, view the client’s machine and data with that mindset, and ensure the safety of the machine and the data you’ve been entrusted with.