The sound card was detected correctly (same as in winme) ES1988 Allegro-1, driver is maestro3. But it won't produce any sound.
Here are some info:
[dummy@localhost dummy]$ /sbin/lsmod
Module Size Used by Not tainted
parport_pc 25096 1 (autoclean)
lp 8096 0 (autoclean)
parport 34176 1 (autoclean) [parport_pc lp]
maestro3 28528 0
soundcore 6276 0 [maestro3]
ac97_codec 12488 0 [maestro3]
nfsd 74256 0 (autoclean)
ds 8456 2
yenta_socket 13056 2
pcmcia_core 57184 0 [ds yenta_socket]
af_packet 14952 0 (autoclean)
sr_mod 16920 0 (autoclean)
eepro100 21844 1 (autoclean)
mii 3832 0 (autoclean) [eepro100]
supermount 15296 1 (autoclean)
ide-cd 33856 0
cdrom 31648 0 [sr_mod ide-cd]
ide-scsi 11280 0
scsi_mod 103284 2 [sr_mod ide-scsi]
usb-uhci 24652 0 (unused)
usbcore 72992 1 [usb-uhci]
rtc 8060 0 (autoclean)
ext3 59916 2
jbd 38972 2 [ext3]

[dummy@localhost dummy]$ lspcidrake -v |fgrep AUDIO
maestro3 : ESS Technology|ES1988 Allegro-1 [MULTIMEDIA_AUDIO] (vendor:125d device:1988 subv:1033 subd:80f1)

[dummy@localhost dummy]$ cat /etc/modules.conf

probeall scsi_hostadapter ide-scsi
probeall usb-interface usb-uhci
alias eth0 eepro100
alias sound-slot-0 maestro3

[dummy@localhost dummy]$ /sbin/chkconfig --list alsa
alsa 0:close 1:close 2pen 3pen 4pen 5pen 6:close

I'd tried to adjusted all parameters in aumix to max, no luck.

Any help?

Hi I just got mine working. The external amp is disabled by default. It is connected to GPIO Pin 3. I know this cause I worked for NEC and I have the schematics and specs.

GPIO= BIT3 = 0x0008

As root do this.

inw 0x1468
0x0111

This shows GPIO 3 is set to input mode. Change it to output mode.
[root@jeff root]# outw 0x1468 0x0119

Unmask the gpio write access.
[root@jeff root]# inw 0x1464
0xFFFF
[root@jeff root]# outw 0x1464 0xfff7

TURN DOWN THE VOLUME CAUSE THE MIC MIGHT FEEDBACK!

Now read the GPIO register.
[root@jeff root]# inw 0x1460
0xF6E7

0xF6E7 + 0x8 = 0xF6EF

Turn on the amp
[root@jeff root]# outw 0x1460 0xf6ef

You've got sound, desuka?

You could probably assume the read values will be the same and then set-up a script to run at startup (/etc/rc.d/rc.local)

// Jeff

Here's an even cleaner solution for those who might care. The maestro driver has an option that better than the above hack. The sound is on much earlier (pre X11) and requires no user intervention.

/etc/modules.conf

alias sound-slot-0 maestro3
options maestro3 gpio_pin=3

Mandrake has HUGE problems with soundcards on laptops in my experience. I have had similar issues with mine, though different card. One simple thing to remember is that by default all channels are muted. Good test if your soundcard is working is to run aumix, if it opens with sliders your soundcard is probably working.

With me I had to give up on Mandrake for use on my laptop. 9.1 kept detcting my card correctly, but the new alsa drivers don't work for my card (crappy es1371). I have always been able to config it manually, but whenever 9.1 boots, it detects my soundcard again and loads the alsa drivers automatically which do not work. I litterally would have to remove the drivers then manually load the drivers every time if I wanted sound. Wouldn't matter what I tried to fix I couldn't get it working. I run Red Hat right now on it and It didn't have any problems running my sound card and I had to do no manual config at all. Sound is one of Mandrake's weak points.

Heeeeeeee Haaaaaaaaaa !
Thanks Jeff ! I have been running linux RH9 for the past couple of months without sound
(I have a NEC with ESS Ellegro / maestro3) same problem, driver loads ok but no sound..
Thanks to your post i cud get it running in a couple of mins .... !!
Heeeeeeee Haaaaaaaaaa !