help with surf pi kit no sound

[Qiaozhi]

just had another look am i testing it right - test from multimeter to ground + to legs of u5 pin 3 11.7 bat volts same pin2 1.48 pin 1 10.48 and yes i need to put new bats in thank you for helping

Since pin 2 (middle pin) of the regulator should be at 0V, and you have the negative terminal of the voltmeter connected to 0V (I presume), then you may have a break in the ground somewhere. Try doing a continuity test from U5 pin 2 to the negative battery terminal. These two points should be connected together.

Think about it.
How can there be 1.41 volts on the regulator GND connection?

Is this a Siverdog (Surf 12 "ApB") long board PCB, or have you made it yourself?

[alcartraz]

Since pin 2 (middle pin) of the regulator should be at 0V, and you have the negative terminal of the voltmeter connected to 0V (I presume), then you may have a break in the ground somewhere. Try doing a continuity test from U5 pin 2 to the negative battery terminal. These two points should be connected together.

Think about it.
How can there be 1.41 volts on the regulator GND connection?

Is this a Siverdog (Surf 12 "ApB") long board PCB, or have you made it yourself?

yes the silverdog long board from +bat to pin 2 15.55 volts continuity from pin 2 to batt - is good from - batt to pin 2 1.37 volts iam lost ??

[Qiaozhi]

yes the silverdog long board from +bat to pin 2 15.55 volts continuity from pin 2 to batt - is good from - batt to pin 2 1.37 volts iam lost ??

OK, let's try a different approach.

What is the voltage between the GND and OUT pins of U5?
Put the meter probes directly on these pins.

[alcartraz]

17 to 18 volts fluctuating
input 11.37 all on the pins of u5

[alcartraz]

right just tryed an old lcd multimeter i had kicking about i have got different readings pin 3 in 11.4 pin 2 0v pin1 out 10.5 that was measured - to ground + to pins on u5 now measured on pins pin 2 and pin 1 11.1 volts ?

[Qiaozhi]

right just tryed an old lcd multimeter i had kicking about i have got different readings pin 3 in 11.4 pin 2 0v pin1 out 10.5 that was measured - to ground + to pins on u5 now measured on pins pin 2 and pin 1 11.1 volts ?

It appears that the previous meter you were using was faulty.
As the output should be 5V, I suggest replacing the regulator (U5). Then take the measurements again.

[alcartraz]

It appears that the previous meter you were using was faulty.
As the output should be 5V, I suggest replacing the regulator (U5). Then take the measurements again.

hi sorry people confusion set in i was testing q2 instead of u5 because q2 looks like the regulators i use in power supply i used to build in my job now tested u5 volts are good 11.4 going in 5 volts coming out i gess stress and trying to do many things all at the same time ?

[alcartraz]

the regulator is ok what do i test next ?

[Qiaozhi]

the regulator is ok what do i test next ?

Check if the negative supply is working by measuring the voltage at pin 5 of U6.

[alcartraz]

i got 5.22 volts on that pin

[Qiaozhi]

i got 5.22 volts on that pin

It should be -5V (or close to this value). Note: It should be a negative voltage.

[alcartraz]

new batts u5 output 4.96 pin 5 of u6 - lead of new meter on ground + lead on pin 5 of u6 is -4.75 volts ? is that right

[Qiaozhi]

new batts u5 output 4.96 pin 5 of u6 - lead of new meter on ground + lead on pin 5 of u6 is -4.75 volts ? is that right

That looks good.
Now (before we proceed any further) please measure the voltages at:
U1 pin 8
U2 pin 7
U2 pin 4
U3 pin 8
U3 pin 4
U4 pin 14
U4 pin 7
U7 pin 14
U7 pin 7
U8 pin 8
U8 pin 4
Please note if they are positive or negative voltages.

[alcartraz]

ok they look all good
u1 pin 8 v12.40 +
u2 pin 7 v 4.97 +
u2 pin 4 v 4.75 -
u3 pin 8 v 4.97 +
u3 pin 4 v 4.75 -
u4 pin 14 v 4.97 +
u4 pin 7 v 4.75 -
u7 pin 14 v 4.97 +
u7 pin 7 v 4.75 -

u8 ? well i cant find that one on the parts list

[Qiaozhi]

ok they look all good
u1 pin 8 v12.40 +
u2 pin 7 v 4.97 +
u2 pin 4 v 4.75 -
u3 pin 8 v 4.97 +
u3 pin 4 v 4.75 -
u4 pin 14 v 4.97 +
u4 pin 7 v 4.75 -
u7 pin 14 v 4.97 +
u7 pin 7 v 4.75 -

u8 ? well i cant find that one on the parts list

Sorry, there is no U8. That was a typo.

OK - let's proceed step by step.
Can you monitor the following points with the scope and post the waveforms here:
U1 pin 3
U2 pin 6 (TP2)
U4 pin 10 (TP1)