Hi,

A few months ago, I discovered that the earth for the front car pre-out wasn't.

here

It was suggested that one of the tracks on the board may have been burnt out if the earth of the RCA had at some point touched a live.

To solve it, I wired the screen of both RCAs to a ground point on the sled and this cured the problem for a while, unfortunately the connection between the sled and the player is not good enough so there is still sometimes a crackle as the player moves in the sled.

I took the player apart again and traced the problem to an SMT component which lies in between the earth pin relating to the front pre-out in the multiway audio connector and the earth of the board. There are two of these components, one for the front and one for the back. The back one has continuity, and the front one is open circuit.

I have attached a pic showing where the two mystery components are, and an excellent artist's impression of what they look like!.

It doesn't seem to be a capacitor as it passes DC, it doesn't seem to be a resistor because the good one registers less than 10ohms. Is it a fuse? does anyone know what it is?

Ive bridged it for the time being as I can't see this doing any more harm than connecting the RCA screens to earth as they already are.

Thanks,
Oli.

It's a 1.2k resistor.

Hi,

I have a variable temp iron and put a wire link across the top of it for now, it seems to have cured the problem.

What is the purpose of this resistor? Is bridging it ok?
I would theorise that because of the high impedance of the amplifier inputs that very little current is drawn from the outputs and that there is very little voltage drop across this resistor, therefore it's purpose may simply be to protect the output stage from over current draw, which in this case it did succesfully.

Since the supply voltage is 12v, the max current that you could put back through that resistor if you accidentally connected the RCA screen to live would be 12/1200=10ma. Therefore the max current you could dissipate in that resistor would be 10ma*12v=120mw. What are those resistors rated at? Could 120mw through that reistor blow it?

I thought it might be possible to measure the value of the good one in situ as I believe one end is not attached to anything as it goes to the header that connects to the docking connector.

Any thoughts?

edit sp.

For some strange reason I actually find that very funny!

You could re-make the solder joints for both resistors. BE CAREFUL if you do this.