earthing rca shields...

[Perry Babin]

Did you confirm that the signal source shield ground had ~0 ohm continuity to the ground terminal of the amp (with the shield to sink jumper removed)?

 

[marko]

Did you confirm that the signal source shield ground had ~0 ohm continuity to the ground terminal of the amp (with the shield to sink jumper removed)?

but it would if it was disconnected surely?

 

[Perry Babin]

Did you confirm that the signal source shield ground had ~0 ohm continuity to the ground terminal of the amp (with the shield to sink jumper removed)?

 

[TO-3]

i've been working from the rca's back to the board, maybe i should work from the other end and see what happens!

where the signal connects to the main board should i have resistance there to the negative terminal like i should at the rca shield?

i will get this sorted this weekend!!!

Wait, from the signal, or the ground? There should be a high resistance on the signal pin to the negative terminal. Now, from the RCA shield to the negative terminal, there should only be up to a couple hundred ohms.

 

[marko]

Wait, from the signal, or the ground? There should be a high resistance on the signal pin to the negative terminal. Now, from the RCA shield to the negative terminal, there should only be up to a couple hundred ohms.

there is continuity at the main board black wires to DB to negative terminal.

but not rca shield to negative terminal.. nothing there at all!

the source cd player is ran off it's own little power supply if that helps?

 

[Perry Babin]

Connect the ground terminal of the head unit's power supply to the ground terminal of the amp's power supply.

Then confirm that the head unit shield ground has ~0 ohm continuity to the ground terminal of the amp (with the shield to sink jumper removed)?

 

[marko]

Connect the ground terminal of the head unit's power supply to the ground terminal of the amp's power supply.

Then confirm that the head unit shield ground has ~0 ohm continuity to the ground terminal of the amp (with the shield to sink jumper removed)?

ok, my findings are as follows, with a wire connecting both headunit earth and amp earth up together the amp works correctly..

from rca shield to neg terminal with both jumper wires connected or disconnected (just leaving power connected for DB) i get very high readings on the mm set to resistance..

 

[Perry Babin]

Check the shield ground as described on the following page:
RCA Shield Repair

 

[marko]

checked headunit as above and that's fine.

 

[Perry Babin]

When you said "from rca shield to neg terminal ....", I assumed that you were talking about the head unit and not the amp.

So... if the amp works properly, the problem was the lack of continuity between grounds of the two power supplies.

 

[marko]

..but i have tried loads of amps in the same senario and they work fine, i don't have to rig both power supplies together to get output!

i'm worried that as soon as the amp is fitted in a car there will be tons of interfearance..

 

[Perry Babin]

The input circuits vary from amp to amp. Not all work the same way.