Mr.Doback

So I picked up my 99 LS400 two weeks ago and its been great. The LCD screen was dead but as I began listening to music, I noticed that if I turn the audio beyond a quarter of a turn, the speakers would cut out for a second then come back, as if someone turned the fader one/off. Since the LCD was dead I was hoping that a new radio would fix the issue (more like hoped, I didn't want to do further diagnosis).

So fast forward to a few days ago, I installed the Beat sonic and my new pioneer double din. The radio install went smooth and it works great, however the issue with the cut out still exists. Now I have to diagnose if either the factory amp or a problem with a speaker.

It does not SEEM like any speaker is blown as the audio is clear. the audio is fine below a certain listening level, but anything above and it begins to cut out quick and evry few seconds. Prior to removal, I faded the audio to the rear and I was able to turn it up a bit more, but it would still cut out. I tried again with the fader to the front only and the issue still occurred.

Should I anticipate that my amp is done? Or begin by testing each channel to see if something is blown? Before anyone says to rip it all out and put aftermarket, I rather not do that, factory audio provides more than I need daily. I am looking for a solution to the issue.

Thanks,
Nathan

Yamae

It sounds like the DC balance on your main amplifier is out of the range and the built-in protection function is enabled.

LScowboyLS

since we often discuss electrolytic capacitor issues here, it might be useful to point out that many car stereo head units and amplifiers in the 1990's had capacitor issues once they get some age, just like the ECU's did!

PureDrifter

iTrader: (10)

only time i've had this happen to me was when the battery ran too low :P

Kansas

If you know someone with a 98-00 LS400 with a working standard or navigation audio system, It shouldn't take long to remove your amp, test it in the car and reinstall it in yours. I've done it and it was quick and easy.

No need to remove the amp from the other car. Not necessary to remove the passenger seat to remove the amp from your car. Tilt your passenger seat cushion forward as much as possible. Disconnect, unbolt your amp and slide it out. Lay you amp on the rear floor of the other LS. Unplug the connectors from the "test car" amp and plug the connectors into your amp.

You may need someone to help you reinstall the amp in your car - someone to slide the tabs on the amp into the slots under the front of the passenger seat while you push the amp forward from the rear floor.

If you need an amp, you might be able to get one through this forum's buy and sell section. I usually see a bunch on eBay .... found only used 98-00 LS400 Pioneer amp on eBay today but didn't look long.

Mr.Doback

You sir are correct. The problem is now solved and here is the solution. I found a blown capacitor when I replaced the amp with a used one. This is what I found. If someone feels froggy, they could replace the capacitor and have a good amp again.

Here is the good amp: All caps are intact.



This is the bad amp, its hard to tell, but the large cap on left is blown.



Thanks again, now I can blast Big L again...

sha4000

iTrader: (1)

Can't really see anything in those pictures.

Yamae

The photo is not clear enough but we manage to recognize the top of the capacitor is blown out and I can see what is coming out.
So the problem was not a simple dry-out of the electrolytic capacitor. The accumulated pressure inside was big enough to cut and open the top fusible line.

Mr.Doback

Spot on analysis. My iPhone couldn't get a clear shot of the blown cap, but this is the best without tearing the amp apart more. I am going to try and get it fixed when I get some time.

LScowboyLS

People keep LS400's for a longer time than most cars, so we have the relatively new problem of electrolytic capacitors not always just dying from some design defect like yours did, but simply of old age!

A capacitor in simplified terms is sort of a really tiny rechargeable battery, and you wouldn't expect a battery to last 15 or more years!