got an amp here (trying to get my junk stash down 
) and it only has output if i earth the rca shields to the heatsink, now i'm guessing this is not ideal and in a car would pick up some pretty bad noises! what would cause this issue? i traced the rca shield all way back to board and is fine, what happens after this is a mystery.
amp is an old philips dap600 (think alpine 3552s)
) and it only has output if i earth the rca shields to the heatsink, now i'm guessing this is not ideal and in a car would pick up some pretty bad noises! what would cause this issue? i traced the rca shield all way back to board and is fine, what happens after this is a mystery.amp is an old philips dap600 (think alpine 3552s
)If you don't have ~0 ohms between the ground terminals of the two supplies, connect them together with a jumper wire. Then confirm that you have ~0 ohms between the shield of the head unit (RCAs not plugged into the amp) and the ground terminal of the amp (amp connected to the power supply).
Remove the ground to the heatsink that you installed and see if the amp works normally.
Ipods cause more problems (due to a lack of a common ground) than any other signal source, that's why I suspected that you were using one.
Remove the ground to the heatsink that you installed and see if the amp works normally.
Ipods cause more problems (due to a lack of a common ground) than any other signal source, that's why I suspected that you were using one.
got an amp here (trying to get my junk stash down
amp is an old philips dap600 (think alpine 3552s
Most likely that the ground-path is missing to the RCA shield. If you open your amplifier and look close to the RCA connectors, there should be a resistor that goes from the RCA shield to EARTH or even a separate audio ground, on each channel.
If you have a meter, measure the resistance between RCA ground and EARTH ground. The resistance can be in a range from 10 ohms up to a couple hundred ohms. I suspect that your resistors may be open.
Can you post a pic of the input stage of your amp?
Jon
In case that does not work out, make sure you hook it all up like Perry said. I had an old amp that would not work without RCA connected they grounded the input section. If an alpine I doubt it would be that way, should have something connected to the RCA shield and eventually to ground inside the amp.
Well, it looks like the two large resistors, in the lower right corner of the daughter board are intact. You can measure across them to verify, but I would suspect that the ground is not even connected to the DB. You may have an open trace on the bottom of the main board, or one of the wires, that connects to the board, may be open, or have a poor contact on a connector.
Let us know.
Jon
Let us know.
Jon
Well, that might be it. You can pull the crimped connectors out of their shells and inspect the wire itself, and using needle-nosed pliers, you can kinda 'smash' the crimped connector to make it a tighter fit, or, you may want to consider just soldering the wires directly to both of the boards. You should not even need to take the main-board off of the sink. The connector receptacles should just pull right up.
I have problems with hum with ipods.
There is no problem if earthed equipment is connected.
So I have a switched earth between zero volts and earth now so I can add or disconnect the earth depending on what is connected.
that doesn't make sense to me, i have rca sheild right up to duaghter board and with mm set to continuity i loose continuity somewhere in the board..
so wouldn't that point to something on the daughter board?
The RCA's are not on the daughter board, correct? I could not see them in the picture that you posted. As Perry asked, earlier, could you post a pic of the other side, as well?
As far as a ground path, the only components that may be in series will be a resistor and possibly a capacitor(in parallel with the resistor). This resistor helps to 'isolate' the grounds by isolating the switching noise from the power supply. So, there should be no other interruptions(ie. IC's or transistors, etc...) in the ground path, other than by the wires connecting to the DB. You may need to pull the board out of the chassis to verify that there are no burnt traces on the bottom of the board.
That certainly helps out! I don't see anything glaringly wrong with the DB. Maybe you can follow the ground traces from the RCA's to where they come into the board. It is possible that there is a small break in a trace???? Not sure, but I think the problem emanates from the main board. Most likely in the main amp or driver stage. Any other results?
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.