My first tip is to go dumpster diving. You can learn a lot with little fear of loss if you’re working on stuff that’s been acquired for almost nothing. Well-funded organisations tend to throw away gear they think is defective, even if it’s for a minor issue. There are also swapfests, Craigslist, and eBay – some of my friends have built impressive hardware labs on a shoestring budget by trawling eBay for great deals and fixer-uppers.
The second tip is when you’re preparing to take a deep dive into a single product, try to acquire three units: one to totally tear down and trash; one to work on; and one to keep pristine, so you have a golden reference to check against. With a little luck, you only have to buy one of these at full price. The tear-down unit can literally come from a trash heap – it doesn’t need to be functional. So long as the PCB traces are intact, it serves its purpose.
In addition to selectively removing components to assist with tracing out wires, I use tear-down units to dry-run risky soldering procedures. Once the correct temperature, airflow and/or soldering tip has been determined, I stand a much better chance of first-time success on the ‘work’ unit.
The pristine unit can be borrowed from a friend – after all, the point is to keep it factory-new, so you have a reference point to sanity-check against. This leaves you with having to purchase just one device – the target you are working on. Of course, time is money. If you’re impatient or don’t like planning ahead, then perhaps your only recourse could be to buy all the samples at market price.
The final tip is to take apart anything that’s destined for the trash heap. Practice makes perfect, and stuff intended for the trash heap is great for perfecting the skill of opening things up with minimal damage, from removing bezels to desoldering RF shields.