I'm going to hazard an educated guess here that the speakers got blown by being played at or near full volume. Even the tiny chip amps used in laptops are capable of delivering a surprising amount of voltage when driven into distortion. This seems far more likely than the speakers just "dying of old age"…

Thanks for the information. It's already a good starting point and gives me hope! In fact, the sound card capacitors aren't electrolytic but ceramic, so they shouldn't have the same defects. Is it possible that so many PowerBooks have no sound? Is there a manufacturing defect in the speakers? Are the coils drying out and not moving anymore? Would there be any noise? Are they burning out? It's a mystery.
Next time I disassemble one, I'll try to extract the signal from the one that should be going to the speakers to see if that's the case with mine too. It's certainly impossible to find new originals. Used ones are likely to be faulty. We'll see. If you have any other experiences, let me know. Thanks!

I restored a 2005 17 inch G4 Powerbook about a month ago. After having it back together there were still a couple things that needed attention, one of those things was no sound. I checked the wiring harness and the connections, but the speakers remained silent. I found a set of speakers in my parts bin and replaced the non-working speakers. It appears that the speakers were what was bad, for the speakers from the parts bin work just fine.

It does seem odd that speakers would just fail and the problem with the original speakers might still be in the connecters or wiring harness. In my case though replacing the speakers did correct the problem.

The rubber surround of a dynamic speaker (the part that crumbles) doesn't produce the sound. Its function is to create an air seal around the cone to increase the efficiency and reduce rattling noises.

Like many electronics d'un certain age, the problem is electrolytic capacitors.

Just a 2 cents guess: all Powerbooks are 20+ years old. The membrane of speakers becomes brittle with time and no membrane=no sound.
However, I wonder if these speakers are close enough to off-the-shelf references or if it is Apple unicorn parts that will mean surgery to adapt (or a pair of amplified computer speakers at a thrift store to be simpler and period correct 😝)

I wonder why so many PowerBook G4s don't have working internal speakers. I own 4 of them and I bought them with non-functioning internal speakers, audio only with headphones. Reading around, it seems like a very common problem. Why? Is it possible that after a while the internal speakers break? And yet they don't have to handle high volumes... Could it be a software problem? Firmware/hardware? Can the situation be fixed? Let me know if you know anything. Thanks!

It would be worth trying to install logic to see if any dependencies might be missing. I use 7.2 and Epic plugins all the time

I switched up, found PT7.4 HD Logic 7.2, OSX 10.5.8, and no luck.

I’m not sure but maybe it could be that the G5, is the A1117 and is pcie and not pci-X.

When I installed the epic tdm bundle, it says it’s a downgrade to, there is a newer version. But nothing in the Protools plugin folder, except the tdm stuff, to route between PT and Logic. No epic plugins show up in PT.

FX5200 and ATI 9000
both didn't work with my mdd

Update... tick tock tick tock 
This story is going to make me suffer  until the very end! :-)

The technician who was supposed to assemble the cable  is a nice  old  technician who has worked for 50 years on  radio and TV repairs and he said to me, "Oh Mario, I'm sorry, but  my hands and my eyesight  no longer allow me to do this kind of work. The  8 pins  to be soldered are too small, you need a steady hand.  Let's wait for the young guy who is just learning  the job to come back,  he's  away for a few days."
And I wait...

Maybe this has gone on long enough…

I've never had the pleasure of traveling to Italy, BUT I have a feeling that the country is advanced beyond pasta and wine in many ways - including computer equipment.

I can find this damn cable on ebay in the US in 10 seconds flat.
I have a feeling that you can easily buy these on ebay in Italy… or at least you should be able to if you can simply do a proper search for it.
If I could read and write Italian I would try to search on ebay.it myself but oh beh, peccato… I can't.

I searched in the US for a "Macintosh mini-DIN crossover serial cable". Translate that to Italian and you may just find what you need. In fact:
You can also simply search for a "Macintosh Imagewriter" OR "Macintosh printer" mini-DIN cable because those are also crossover cables.

I'm just sayin' here that considering the complexity of what you're attempting to put together, this effing little cable should NOT be the hardest part.

Here's just one of the US ebay finds: https://www.ebay.com/itm/232343545580?

buona fortuna a te

Hack & Whack / Temp "Test Approach"

If one has a straight-through cable to butcher.

Why not cut the cable and simply twist test necessary pairs together?
Realize this isn’t a permanent solution — perhaps a good temporary test?

 

    Black to Brown / Yellow to Red / Purple to Green / Blue to Blue / Orange to Orange

---

Color coded wires from a straight-through cable, with associated pinout(s):



Cut the cable close enough to one end that it could then afterwards,
possibly be soldered to a new plug. *Of course, before cutting it “close
enough” / also allow an ample length for this possible “twisted pair test”.

It might look like absolute hell with all the wires exposed & twisted together
in this manner, until a more “finished” cable could be created or acquired?

---

OR Does an old Apple printer cable 590-0552-A (below)
equal an Apple Mini DIN 8 Crossover Cable TX-RX?

Looks like this one does. (Or so says side-by-side testing with a multimeter.)
Had a little free time last night in the now, seldom visited, cable cavern here.


*Above not color coded to match the actual wiring colors.

Had one of these in the “boneyard” and continuity testing provided the above results
… which seems to “fit” the descriptions of the now seemingly rare crossover cable.

Another different cable here, marked F2V024-06, w/ a taped label of “IMG-II” attached;
its continuity tested out the same as the above shown 590-0552-A cable.

But if you really want to get out in the proverbial weeds with this…
our distinguished forum member part12studios (PM him) chased
this very same problem waay back in the year 2016.

Here:
https://www.doityourself.com/forum/computers-internet-capable-devices-peripherals/566685-8-pin-null-round-modem-cable-wiring-help-needed.html

But seriously now -- and yet again... ALL kudos to GaryN!