Saudio Amplifier (?) Stopped Working After A Jump Start...

[GS430SE]

Audio Amplifier (?) Stopped Working After A Jump Start...

(sorry about the typo - the site won't let me edit it)

My 2004 GS430 has the Mark Levinson stereo + satnav system. I attach a pic of the head unit.

The CD changer is in the back of the glovebox. The satnav DVD reader is in the boot (I think the amp is below it). Everything was original/factory-installed, not after-market.

Great audio quality... that is, until, faced with a flat Battery, I had to jump-start the car (from a portable Battery, not from another car).

The audio power switch may have been on when I did this.

From that time on, there are no sounds at all from the audio system (CD, tape, radio, all silent). The CD apparently plays, as does the tape, and the radio apparently tunes just like before. But, there's no sound at all from the speakers.

When I press the Audio button on the head unit, controls like "Bass", "Treble" and "Front/Rear--Left/Right Balance" are all greyed out on the display. So, the computer knows that something is wrong.

Everything else worked as before.

I thought, this should be easy to fix - a fuse has blown somewhere, probably in the amp, methinks.

But, I couldn't find any such fuse... Google didn't help, either.

So, I took it to a Lexus dealer who kept the car for a couple of days. They couldn't figure it out, saying that the amp itself (not a fuse!) was probably "blown"... sounds bad. But then, they've got things very wrong before about the same car - e.g., an earlier, unrelated fault (which I later found, no thanks to them, was a sticky brake caliper) was missed by the same dealer, and instead I was told non-premium tyres were the cause of the sounds and vibration about which I was complaining.

Help! What should I do about this Sound of Silence, please?

[TigerFish]

Have all the fuses been checked? The 30 Amp fuse marked "Radio No. 1" is the fuse for the amp (Engine bay Fuse box). Other fuses that effect various parts of the stereo are 10A "Dome" fuse, and the 15A "Radio No. 2" fuse (both in the footwell fuse boxes).

For info, the amp is located in the footwell next to the glovebox.

[GS430SE]

Thank you, TigerFish!

I now have more information so I'm starting a new thread, without a typo in the title (which I can't change) on the problem,