Self Diagnosis Screen self test on the SC 430

[ThomasD94]

On 6/9/2020 at 9:47 PM, Neil E said:

I think the best bet would be to get the same model from a facelift car, assuming it's the same. Have you opened it up to look at the connections on the PCB?

If it is a cracked /dry solder joint or something similar it might be worth a repair. It must be something like that for it to work intermittently.

https://svtservices.co.uk/lexus-mark-levinson-power-amp-repair-service/

There is a thread on here or clublexus that goes into the problem of the connections on these amps with a close up pic of a broken connector where it joins the board but I can't find it. I suspect that if all of the pins are okay then this could be the fault. 

Hi Neil/all,
So I have narrowed my audio issue to the wires that come from the frame of the car to the connector. When I hold the wires the apart a little about 5-7cm from the connector the audio works fine. As soon as I bolt the amp into the body of the car and the wires are tight again the audio drops. Any chance you know of a remedy?

Thanks, Thomas

[ColinBarber]

possibly a bad solder joint on the connector socket, a cracked track on the board near the connector, the pins on the plug need to be bent to give a better mechanical connection, or a break in one of the cables near the connector plug.

Are you able to take a close up of the just the one PCB connector which is causing problems, rather than a picture of the whole board - both top and bottom.

[Neil E]

I agree with everything Colin says/asks but can you also identify which wire when 'wiggled' causes it to connect? Is it the blue and white wire perhaps? I think that will be the head unit to amp remote turn on. 

[ThomasD94]

On 6/14/2020 at 9:47 PM, ColinBarber said:

possibly a bad solder joint on the connector socket, a cracked track on the board near the connector, the pins on the plug need to be bent to give a better mechanical connection, or a break in one of the cables near the connector plug.

Are you able to take a close up of the just the one PCB connector which is causing problems, rather than a picture of the whole board - both top and bottom.

I can try yeah 🙂 It is going into Lexus Glasgow tomorrow morning and I am going to ask them to test the amp too 🙂

[ThomasD94]

Here is some I took tonight

[ThomasD94]

It does have me bamboozed/almost pulling my hair out haha

[ColinBarber]

Looks ok from what is difficult to tell just from photos. It seems to have had quite a lot of rework in the past, I wonder if chasing the same fault or something different.

I think the fact that you can make the fault occur by touching the wiring is probably the best place to continue the diagnosis. I'd remove a section of the black wiring shroud back to where you were moving the wiring so you can move each individual wire to identify which one has a problem. It could well be a break in a wire if the harness has been moved a lot in the past, or it could lead to a problem at the connector/pin - especially if the wiring is a little tight when fully assembled and there has been any strain.

[ThomasD94]

On 6/25/2020 at 9:02 AM, ColinBarber said:

Looks ok from what is difficult to tell just from photos. It seems to have had quite a lot of rework in the past, I wonder if chasing the same fault or something different.

I think the fact that you can make the fault occur by touching the wiring is probably the best place to continue the diagnosis. I'd remove a section of the black wiring shroud back to where you were moving the wiring so you can move each individual wire to identify which one has a problem. It could well be a break in a wire if the harness has been moved a lot in the past, or it could lead to a problem at the connector/pin - especially if the wiring is a little tight when fully assembled and there has been any strain.

thank you! I really appreciate your help!! I will let you know how I get on 🙂

[kcdionysus]

@ThomasD94 Hi Thomas… did you ever get to the bottom of your stereo/amp problem? I’m having a very similar sounding issue with my SC.

[kcdionysus]

So to conclude my stereo issues, it was the amp. I ended up getting a decent set of old headphones, wrapped some wire around the rings on the jack plug & touched it onto a couple of the wires in the multiplug as per the wiring diagrams above and I could just hear the line level sound coming though so the head unit was fine. 

So things to note… even though my old amp fan ran initially and the ‘secret menu’ suggested the amp was ok on the network, it doesn’t mean the amp isn’t faulty as clearly mine was. I was hopeful it was something else but alas not. 

Also, I tried another amp from another Lexus model (GS 1999-2005 I think) with the same exterior multi plug setup as mine. I was fortunate enough to find an eBay seller who was happy to send me this unit to try it. I plugged it in and it worked… sort of… but sounded awful and even messed with the radio reception. So even thought these Mark Levinson amps look the same, they’re clearly different internally. But I appreciated this sellers trust and effort in sending it to me. So I would suggest sticking with the known SC430 ML model amps - 86280 0W070 and 86280 0W250