Amp 10 problem?

[maoravni]

Hi,

I've just complete my Amp 10, and have trouble starting it up.

the board passed the 5V test, so I completed the board and hooked it up.

After connecting the amp, the LED doesn't come on.
I've tried in both polarities, but nothing.
I do see a voltage change across the LED between muted and unmuted positions.

I tried connecting a cheap speakers to the amp, and found two strange things:

1. One channel has a DC offset and is making noise.
2. The other channel enters into protection when the speaker is connceted.

Any ideas?

Maor

[maoravni]

One more thing:

voltage checked across speaker terminals is ~2.7V.

[viccpa]

@maoravni

I have the same problem. LED won't work. One channel goes into protection and another work fine about 6 seconds and start to make noise.

Please help us!

Thanks in advance

[maoravni]

If I remember correctly, the problem is that you don't have any source connected to the amp. Try connecting a source and then measure the voltages. I don't know about the LED, since I didn't connect it to the board eventually.

Hope this helps.

Maor

[V-bro]

Hi guys, you should short the input and connect a load (speakers) to the outputs and then zero the output voltages.

Further more it sounds like you guys have some bad solders on the small yellow caps. When they don't make good contact you get noise....

------X-max. can be several meters on any driver, too bad it can be done only once...------

[blanka]

Somewhere on the bottom, I think near R98 R99, there are some contacts that are so close to each other, which gives a big chance to short while soldering. Check your solder work there.

[viccpa]

@V-bro
I totally forgot to short input. Thanx.

Now, everything is OK, I trimmed the output voltage, sound is very nice.

except the LED.

[manoweb]

quote:Originally posted by V-bro

Hi guys, you should short the input and connect a load (speakers) to the outputs and then zero the output voltages.

Well the instructions I have received clearly state not to connect any input or output, zero the voltage, and only when all is OK go and attach input and speakers. Page 5 and 6 of the Assembly Instructions (AMP10b)