Panasonic CF-52 no sound built in speakers

On a fresh updated install, there is no sound from built-in speakers. Headphone jack works. This bug is possibly similar to #632046.

I have checked that the Fn-f4 has not muted the sound.
alsamixer indicates that sound is not muted.

I previously had kubuntu installed and sound worked for some time.

Ubuntu release 16.04.1 LTS

alsa-base version 1.0.25+dfsg-0ubuntu5
---
ApportVersion: 2.20.1-0ubuntu2.1
Architecture: amd64
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC0: nav 1339 F.... pulseaudio
CurrentDesktop: Unity
DistroRelease: Ubuntu 16.04
InstallationDate: Installed on 2016-09-16 (1 days ago)
InstallationMedia: Ubuntu 16.04.1 LTS "Xenial Xerus" - Release amd64 (20160719)
Package: alsa-driver (not installed)
ProcVersionSignature: Ubuntu 4.4.0-36.55-generic 4.4.16
Tags: xenial
Uname: Linux 4.4.0-36-generic x86_64
UpgradeStatus: No upgrade log present (probably fresh install)
UserGroups: adm cdrom dialout dip lpadmin plugdev sambashare sudo
_MarkForUpload: True
dmi.bios.date: 06/05/2009
dmi.bios.vendor: American Megatrends Inc.
dmi.bios.version: V2.52L13
dmi.board.name: CF52-2LA
dmi.board.vendor: Matsushita Electric Industrial Co.,Ltd.
dmi.board.version: 1
dmi.chassis.asset.tag: No Asset Tag
dmi.chassis.type: 10
dmi.chassis.vendor: Matsushita Electric Industrial Co.,Ltd.
dmi.chassis.version: 001
dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvrV2.52L13:bd06/05/2009:svnMatsushitaElectricIndustrialCo.,Ltd.:pnCF-52GFNBX2M:pvr002:rvnMatsushitaElectricIndustrialCo.,Ltd.:rnCF52-2LA:rvr1:cvnMatsushitaElectricIndustrialCo.,Ltd.:ct10:cvr001:
dmi.product.name: CF-52GFNBX2M
dmi.product.version: 002
dmi.sys.vendor: Matsushita Electric Industrial Co.,Ltd.