The speaker in my trusty Technics PR100 piano developed a horrible buzzing sound, especially noticeable when playing a D major chord!
Luckily, the service manual is available at archive.org, here.
Following the manual, getting into the piano is really easy. Remove the lid, undo four screws and the control panel hinges nicely away, what design!
Removing the lid is pretty simple, you need to use your fingernail to pull the little latch back on the left of the lid, then you can lift it up and out, as per the photos below.
There are then two screws on the bottom and two on the back to undo.
The top then hinges away – easy!
The speakers are underneath the plastic covers on the left and right, and look like this:
The Technics part number for the speaker is EAS-16PL403A, but they won’t have been manufactured for many years by now, so we need to find a replacement.
This Amazon review suggests that the Fenton Skytec 6.5 inch 175W speaker will fit, so I bought two of those. But, the plastic cover didn’t fit over it at all, so they had to go back. The covers are pretty important – they, along with the padding inside them, stops resonances in the cavity which could get annoying.
To cut a long story short, the Visaton W170 6.5″ Woofer is a good substitute. They are available from CPC, here. They fit well under the covers and despite the slightly smaller magnet, they sound the same as the factory ones to my ear. Not that it really matters too much – anything is better than the horrendous buzzing of the old ones!
The spade connectors from the existing wiring doesn’t fit onto the new speakers, so I simply cut the old spade connectors off the wiring and soldered directly to the new speakers.
All in all, it isn’t necessarily a particularly difficult job, but if you’re not confident then any domestic electrician should be able to follow this site and do the job for you.
Whilst I was there, I took some photos of the circuit board, incase they’re useful to anyone.
I hope it lives forever!