Bought a XY LM3886 Kit.

[Corpius]

Originally Posted by AndrewT

Where did the 3886 come from?
Was it China or similar disreputable country?

China indeed. The LM3875 kit came from the USA. This one is working flawlessly. Volume control and input selection via remote control is also working as supposed to be. Now all i have to do is finish the chassis and rewire it all in a neatly way.
This kit also came with a manual. The China kit did not

[pacificblue]

You interrupted signal ground and power ground on the PCB by scratching away the thermals. Now the signal ground is floating. That is the reason why the output swings to one rail.

You need a connection from signal ground to the power ground. For a test take a wire from the IN GND terminal to the OUT GND terminal and check, if that solves the issue.

[Corpius]

Originally Posted by pacificblue

You interrupted signal ground and power ground on the PCB by scratching away the thermals. Now the signal ground is floating. That is the reason why the output swings to one rail.

You need a connection from signal ground to the power ground. For a test take a wire from the IN GND terminal to the OUT GND terminal and check, if that solves the issue.

That sounds plausible. I thought I did it just like Aguilabrava did. I guess I did it wrong. I will try it later this week. Thanks for your reply!

[Aguilabrava]

Corpius, by looking at your pictures you did cut the ground bridges the right way, I think what Pacificblue is telling you is that ALL grounds need to be connected so the input GND isn't floating. Just connect the GND's and test again.

[Corpius]

Originally Posted by Aguilabrava

Corpius, by looking at your pictures you did cut the ground bridges the right way, I think what Pacificblue is telling you is that ALL grounds need to be connected so the input GND isn't floating. Just connect the GND's and test again.

I do not get it. Are you trying to tell me that the input ground needs to connect to the power ground? Why where the bridges cut then?

[Aguilabrava]

The connection has to be done outside the PCB, that's why the bridges were cut.

[Aguilabrava]

Pemo:

I already ordered 2 of those PCB's you found, nos vamos a divertir sin duda alguna... (We'll have fun, no doubt about it---for those of you that can't read Spanish).

[Aguilabrava]

By the way, when I talk about the quality of the components of these XY LM3886 kits, I'm basically referring to the very cheap and low quality electrolytic capacitors included in the kit, and the resistors which are good quality metal film but way too small, I have read that the ideal wattage in the resistors for this type of amplifiers should be 1/2 watt.
Now, when I ordered the kit I kind of knew this, the two PCB's including the two LM3886TF and everything else sells for $17.99 with free shipping from China. Each LM3886TF here in USA sells for $8.50 plus shipping, so even if one has to discard those horrible capacitors and replace the resistors with bigger ones, it is still a bargain. I used the PCB's, the LM3886TF's and the connector blocks, everything else was upgraded and my amplifier sounds just great.

[fabricated]

Man I'm really glad your amp turned out the way you wanted it too..... Do you have any pictures of the amp hooked up to your speakers?

[pacificblue]

Originally Posted by Corpius

I do not get it. Are you trying to tell me that the input ground needs to connect to the power ground? Why where the bridges cut then?

An attempt to avoid possible ground loops.