[jin]

Here are a few pics of my Logic7 amp circuit board. I pulled it apart because the underseat woofers were barely audible.

Is there anything obviously wrong with it? Is the green goo supposed to be there?

Next step will be to buy a multimeter. Or maybe just take to a shop see if they can fix it.

[jin]

More pics

[ctuna]

There were kits on Ebay consisting of mostly the bigger electrolytic
capacitors. There was a guy in Berkeley replacing the driver chips in the
7 Series he would even upgrade them to a more powerful version .

Your best bet it to get in touch with these guys.

http://www.diyparadise.net/logic_7_repair_kit.html

[ptpending]

this amp have 9 channels (center, front left door, left sub, left rear door, left shelf,right front door, right sub, right rear door, right shelf)
you see them, 6 large and 3 small chips
sub pins in 20-pin connector is 8/18(left) and 6/16(right)

[jin]

What needs to be changed? The caps or the ICs? Attached is a pic of the 3 small ICs with the thermal grease removed. Two have the same numbers. Are they the two bass ICs?

[csu87]

you sure its the amp and not the speakers? 8year old OEM speakers tend to go bad...

[jin]

Originally Posted by ptpending

this amp have 9 channels (center, front left door, left sub, left rear door, left shelf,right front door, right sub, right rear door, right shelf)
you see them, 6 large and 3 small chips
sub pins in 20-pin connector is 8/18(left) and 6/16(right)

Do you have a chart or diagram showing which chips are which? The 6 large ones all look exactly the same. Seems that 2 of these 6 chips are the woofer chips.

[ptpending]

one chip for two subwoofers, use multimeter to trace chip from 20-pin connector
i've provided subwoofer pins earlier

[teamben158]

The green goo is supposed to be there. It's some sort of epoxy/rtv that holds those caps down. Without it, the leads tend to break after extended vibration.

[jin]

Originally Posted by ptpending

one chip for two subwoofers, use multimeter to trace chip from 20-pin connector
i've provided subwoofer pins earlier

How do you know there is one chip for the woofers and the pin locations?

[jin]

Originally Posted by csu87

you sure its the amp and not the speakers? 8year old OEM speakers tend to go bad...

I removed the woofers underseat and hooked them up to my home stereo system. They were perfect. Sounded nicer than my Tannoys in fact

[ctuna]

I would get the part no of the large chips and
see if I could get the spec sheets. the other way of telling
where the channels come from it to back track from the output
pins with and ohmmeter unless you can get a schematic.
The part no's you have exposed are a voltage regulators and a FET.

[jin]

Got the part numbers of the ICs and 2 of them are the 70w/4ohm so must be the woofer ICs.

Have ordered new ones and will solder them in. If it works will make a DIY.

[ctuna]

Do you have pictures of the two?
It would be interesting to see the spec sheet.

[ptpending]

Originally Posted by jin

How do you know there is one chip for the woofers and the pin locations?

because, as I said before - there are 9 separate channels, and you have 9 chips inside

[ctuna]

They could be dual channel chips and bridged on the bigger channels.
The power board shows 6 large chips that are likely to be the output
chips. 9 channels is right but two are at 70 watts and the others at 40.

[jin]

Originally Posted by ptpending

because, as I said before - there are 9 separate channels, and you have 9 chips inside

There are 6 ICs only. The 3 small chips are not ICs - 2 are rectifiers and 1 is a FET.

Originally Posted by ctuna

They could be dual channel chips and bridged on the bigger channels.
The power board shows 6 large chips that are likely to be the output
chips. 9 channels is right but two are at 70 watts and the others at 40.

Bingo. 4 of the chips contain 2 amplifiers in a bridge configuration. The output power is 2 x 40W/2 ohms.

[jin]

Originally Posted by ctuna

Do you have pictures of the two?
It would be interesting to see the spec sheet.

When I cleaned the grease off the 6 lCs there were no part numbers showing but I was able to I gently lift them up enough to see the part numbers underneath.
ICs are 4 x TDA8566Q and 2 x TDA1562SD.

Datasheets attached.

[ctuna]

Nice just as I thought there are dual channel and single
channel chips. Thanks. I wonder how they get 9 channels then
are there some chips on the bottom of the board?
I only count 6 chips 2 for the bass channels and there would be 4
left which is enough for 8 25 watt channels so are there two on the
bottom of the board if they are bridged.
O I get it there running 2 ohm speakers at 40 watts.

Where you able to order the chips?
How much were they?

[jin]

Ordered from ebay. Hopefully they are genuine and work okay.

[ctuna]

Saw some on the net for about 15 bucks US each

[jin]

Yes paid $15 each. Fingers crossed this is a $30 fix