I recently had the pleasure of winning a bid on an old Lenovo Thinkpad W530. What a damn beast! i7-3740QM quad core with hyper threading, 16gigs of RAM, a total of THREE possible hdd slots, and an Nvidia Quadro K1000M driving a really nice and bright fullHD display!
There is only one issue: The speakers. They are stupid silent to the point of not being excusable.
I am exploring a way to fix this by adding an additional amplifier between mainboard and speakers.
As can be seen above, on page 79 of the schematics (link in the comments below) seems to be the power distribution schematics. There are a couple candidates that are interesting here: VCC5M, VCC5B, and most importantly because likely switched with laptop power: VCC5M_OUT which can be had at the inductor L3. According to the documentation above the pin name it appears to be able to 22Amps. Seems like a lot and could mean that 1.5A might be available to my little Class-D amp. More on this later.
Looking at the board layout gives me L3 in a location that is covered by the magnesium frame. Magnesium. Metal. That's gonna hurt me at some point.
However, this board file viewer is really cool and clicking on the signal reveals where this signal goes! So I found these guys:
And these guys are located here:
Happy as I am to find exposed and seemingly very well supported pins (lots of vias visible making these pins very good candidates) I take my multimeter out and start measuring. Sure enough, I find 5.17 volts and on the other sid/!@#$%^&POWEROFF
The overall power and quality of this laptop makes it impossible to ignore that the speakers are terrible. I want to be able to use YouTube or any other audio producing software without using headphones all the time. Or video conferencing, now that we are in the midst of a global pandemic. This stuff just has to work these days. Clicking on the first test video was therefore a huge disappointment. The speakers are high pitch and annoying and on top of that extremely silent. I almost feel lied to because the size of the speaker grills speak a completely different language. They are even taller than the keyboard and over an inch wide.
A quick google search revealed: Every W530 user first wonders if their laptop is broken and then resigns in despair that it's not. How can this be? This is certainly not the first Thinkpad. Speakers were always a weak point but usually not THIS bad. It's almost a statement by itself: "We know it's shit, we don't also want everyone around you to notice!!"
Well, shit or not, my idea is to install a PAM8403 5V stereo 3 Watts amplifier inside of the laptop to drive the existing speakers with more power. At least at first. Maybe, I'll test custom speakers at a later point but there is really not that much vertical space available to install something like modern MacBook speakers or similar. Louder is fine for now. Quality can come later.
The PAM8403 is a tiny 5V amp that has been tested by many and declared good enough for most small projects! It costs next to nothing and comes on breadable breakout boards ready to run.
During my first tests I noticed that it does NOT run on the 5V power provided by a USB port. It constantly dies and clips and is generally unusable. It needs a real 5V power source and that will be the primary concern for the whole project. The board is small enough to fit nearly anywhere but power needs to be had in order for it to function properly.
I did some primitive tests with two different, salvaged laptop speakers and so far, I'm pretty happy with the output. I'd guess about 10 times louder and still reasonably clear. Full blast is a compromise but I rather have some minimal clipping than not being able to hear a speaker because some wall heater turned on.
Tasks for the next couple weeks: Identify a 5V source inside the laptop from which I can draw about 1.5A under full load (2 x 3Watts). That might be more challenging than usual since I don't have any schematics or diagrams from this laptop and don't want to take the entire machine apart to find it. We'll see. It's a big laptop and I'd be surprised if I can't find one Amp somewhere.