Hi there - one speaker (of 8) in my car audio system is not working. The speaker has been tested independently and works fine. The amp was located under the drivers seat and suffered road salt corrosion, some of which is visible on the PCB. In fact a surface mount capacitor has now fallen off. I think the cap is shot (open circuit when I put the multi-meter on the electrodes, which are almost corroded off). I could unsolder a similar cap and test the value, but I was wondering if there is an alternative "trial and error" approach I could take to validate if this is the source of the problem? I have attached 2 pics - one of the full amp, the second a zoom in on the cap in question (before it fell off, you can see the green corrosion).
Thanks
Thanks
Attachments
If you remove the rest of the thermal pad from the IC, can you read the part number?
Using the corresponding parts from another channel is a well used practice.
In the attached image, the via looks like it might be damaged. This may be the case for other vias as well, especially those that are green.
Using the corresponding parts from another channel is a well used practice.
In the attached image, the via looks like it might be damaged. This may be the case for other vias as well, especially those that are green.
Attachments
Hi again - I found a datasheet here:
Datasheet for TDF8590TH/N1S,118 NXP Semiconductors Amplifiers - Audio | Octopart
I think the circuit is shown in Fig 10 (attached), but I'm not 100% sure. My car has 8 speakers, and there are 4 of the TDF8590's on the board, so I am assuming they are configured in the 2-channel mode (per Fig 10).
Thanks
Datasheet for TDF8590TH/N1S,118 NXP Semiconductors Amplifiers - Audio | Octopart
I think the circuit is shown in Fig 10 (attached), but I'm not 100% sure. My car has 8 speakers, and there are 4 of the TDF8590's on the board, so I am assuming they are configured in the 2-channel mode (per Fig 10).
Thanks
Attachments
Checking with a meter isn't definitive. It may show continuity but doesn't show the condition. If the pads look different (corroded/burned) and it reads like a dead short, I'd scrape the copper clean on each side of the board and use a wire to reinforce the path.
It looks like the caps are 0.1uF. That's a typical value for local bypass caps.
It looks like the caps are 0.1uF. That's a typical value for local bypass caps.
Perry - I replaced the cap and repaired the via and it works!!!
Two last (I hope) questions:
1) I don't have green Sil-PAD as was originally applied between the IC's and the casing of the amp (heat sink). Can I use Thermal Paste instead?
2) So this does not happen again, I am going to isolate the amp from the carpet of the car by placing it in a plastic / silicone tray. In the original install, the amp was attached to a metal plate, which is turn was attached to the body of the car (i.e. to ground). Do you know if the an amp casing is typically bonded to ground directly, or via the wiring harness?
Thanks,
dave
Two last (I hope) questions:
1) I don't have green Sil-PAD as was originally applied between the IC's and the casing of the amp (heat sink). Can I use Thermal Paste instead?
2) So this does not happen again, I am going to isolate the amp from the carpet of the car by placing it in a plastic / silicone tray. In the original install, the amp was attached to a metal plate, which is turn was attached to the body of the car (i.e. to ground). Do you know if the an amp casing is typically bonded to ground directly, or via the wiring harness?
Thanks,
dave
Good quality heatsink compound should be OK.
The wiring is done through the harness.
I wouldn't put it in a tray that could hold water. Can you simply use some spacers to lift it up, using the same or longer screws to mount it in place?
The wiring is done through the harness.
I wouldn't put it in a tray that could hold water. Can you simply use some spacers to lift it up, using the same or longer screws to mount it in place?