ok I mounted the amp inside the speaker cab, tried it first with the tweeter/horn and it was hissing but the amp doesn't go in protection and volume makes the hissing get louder. I then tried with the speaker only and the same result only difference is that the noise isn't a hiss but a crackling sound with a continuous airplane noise in the background. Tried with both horn and speaker and still the amp didn't go in protection mode so noise apart I think we've got it on the right road.

what's next?

Merry Christmas to all and have a wonderful New Year!!

Ok the only problem is that I can't attach one speaker at a time, the tweeter and speaker are both attched to the same 4 pin plug

went ahead and fitted in the thrid and last amp chip, the current limiter lights up at first then goes down to a dim glow, pin 3 for all amp chips is 0 and pin 8 is -2.3v.... what next?

opinions?

thanks

Is the -2.5v on pin 8 indication that the chip(s) need to be replaced? If the 0v on pin 3 means the output is correct, then should I proceed to fitting in the thrid and last amp chip in the U7 position?

Also where do I find the correct length chip amp mounting screw isolation washer for this sort of amp chip?

thanks

Fitted in another chip amp in the U8 position, tested the voltage on the output pin, 0 volts and pin 8 is -2.5v.. The limiter lamp lights up very dimly (it's 40watts), is this normal? Should I proceed to placing the last chip amp in the U7 position?

Ok I fitted in another amp chip and this time it behaved properly, going to zero on pin 3, however I'm still getting -3v on pin 8.

After pulling the first amp chip, I remeasured the voltage on pin 8 and was getting -13v, so the -3v once the chip is fitted in must mean that the amp chip is pulling the negative voltage down or is this normal?

thanks

No the output pin is giving me around 31vDC.

I checked the voltages with this amp chip soldered in, -ve voltage to pins 4 & 6 are -37 but on pin 8 I'm getting -3 instead of -13, could this be indication of a fried chip?

thanks

got it fixed it was a shorted jumper just like the other one!!

Anyways fitted in one of the amp chips in the U5 position, clipped the meter leads to the output pins for the tweeter, gave it a short burst through the limiter and the tester went above 2vDC, I changed the meter setting to 200v and the amp gave me around 31vDC... so it's a bummer?

thanks

Well I'm having a hard time trying to understand where exactly should I connect the meter clips for the output test, U5 in the schematic is connected directly to J2 and J6 but there's no continuity from pin 3 to any of the connector pins... another shorted jumper?

maybe a silly question, but isn't pin 3 on the BA6110 supposed to be positive?

sorry for the late reply, finally got down to getting the readings off the opamps, from U1 to U4 which are BA4560N's getting -13.8 off pin 4 and +13.7 off pin 8 so that looks normal. U6 BA6110 here's what I'm getting:
Pin1 = 0.5v
Pin2 = 0.5v
Pin3 = -12.7
Pin4 = -12.9
Pin5 = -14
Pin6 = 2.8v
Pin7 = 2.8v
Pin8 = 2.7v
Pin9 = 13.7v

Pins 6 & 7 are soldered together. Everything look normal here?

would it be wise to take the voltage readings of the opamps first? (BA4560's and BA6110)

As for the "treble amp" position, do you mean U5? And if so that would mean clipping the meter to J5 and J6 right?

Only the jumpers are done this way, all the other traces are on the underside of the board. Have you taken a look at the chip amp voltage chart?

new voltage chart for the chip amps (not installed):

http://www.flickr.com/photos/73835524@N00/11291983513/in/set-72157638111984374