High voltage on the j4 section

[j'ke]

Hi everybody,

Just got myself the xox and my power supply is just finished.

I tested every resistor before i started like the manual said and i did the voltage test on every step.

So far everything worked very well. Untill i came to the J4 section for the jumper wires.

My 5.33v reference is perfect, but if i test the other pin i get 25V DC instead of 12V DC.
I red the troubelshooting fact but it didn't help me.

Does anyone have a idea please?
Thx a lot!

[aminoacid]

hi!

i would start out by checking the voltage divider (r178 2.2k and r179 1.8k).

see that there is no loose solder joint and that they are the right ohm.

also see (with power off) that you have connection between r179 and pin2 of ic23.

[j'ke]

The r 178 and r179 are ok. Both have the right ohm and they are soldered in properly.

The connection between r179 and pin 2 of the IC is also ok.

I turned it off when i wrote this thread and started to make music untill now. And now when i wanted to test J4 again i don't have anything anymore.

Going to look on the forum for IC voltages, so i can see that it still works.

thx for replying!

[guest]

there is definitely a bad joint in that area
or your opamp is blown
what are all the voltages on ic23

[j'ke]

i hope i tested it right. I holded one of the multimeter wires on IC20 for ground (is this correct)? And the other on the opamp.

I got almost nothing

pin1: 0 V
pin2: 0 V
pin3: 0 v
pin4: 0 v
pin5: 5,33 v
pin6: 0 v
pin7: 0 v
pin8 0,5 v

This can't be correct

[guest]

thats some bad news

measure the voltage
on either side of r1 and c3

[guest]

also
is anything getting hot
and are you using a 9v AC supply

[j'ke]

hmm strange things are happening. Now i got 13,65 V DC on C3. When i just started this was 14,96 V DC.
And over R1 i got nothing 0,00 V DC

But when i test the ohm it is still perfectly 100ohm

[j'ke]

also
is anything getting hot
and are you using a 9v AC supply

Not really hot no. And i'm using a 9 vAC power supply. The kit came from our german friend on xoxshop.de and he added the power supply.
I tested the power and it was 10,5 v AC. So no probs there.

[guest]

what are the voltages on either side of r1
put the black probe on ground
and test both sides of r1 with the red probe

[j'ke]

Oh sorry,

One side has 28,5V and the other 27,2V

Thx for helping me!

[guest]

no worries
measure the voltages on ic23 again
one side of r1 touches ic23
so there should have been 27v on one of those pins

[j'ke]

Yes indeed, this is correct.

[j'ke]

I think i bought a crappy multimeter.
Now i get

pin1: 25,5v
pin2: 11,5v
pin3: 5,5v
pin4: 0v
pin5: 5,5v
pin6: 5,5v
pin7: 5,5v
pin8: 27,5v

Is this more like it?

[guest]

all those look good
check j4 again
it seems like its working