• WANTED: Happy members who like to discuss audio and other topics related to our interest. Desire to learn and share knowledge of science required as is 20 years of participation in forums (not all true). Come here to have fun, be ready to be teased and not take online life too seriously. We now measure and review equipment for free! Click here for details.

DIY: Summer Projects

solderdude

Major Contributor
Joined
Jul 21, 2018
Messages
2,134
Likes
3,418
Location
The Neverlands
red - a via. This is used to continue a trace from the bottom side to the top side.
When I would have designed the PCB I would have put a soldermask (the black 'paint') over the vias.
Vias usually have a smaller drill hole, typically 0.6mm
 

Silou

Active Member
Joined
Oct 5, 2018
Messages
187
Likes
63
Good to know, thanks for the explanation. Do you know if there are any jumper cables for PCBs like this one? I only found some for the Raspberry etc. , but they are far to thick.
 

solderdude

Major Contributor
Joined
Jul 21, 2018
Messages
2,134
Likes
3,418
Location
The Neverlands
I would just use wire.
For the power supply I would use something like 0.4 to 0.5mm2 or even 0.75mm2
 

Silou

Active Member
Joined
Oct 5, 2018
Messages
187
Likes
63
Which one is U5 and which one is U6? No idea how to identify them.

Some more questions:
No diodes on the negative board? (LED?)
How do I know if Q2 is still working and functioning? It was really hard to solder Q2 to the board, because it does not want to take any solder to make a solid solder joint.

What about R19 and R23 on the negative board? R19 & R23 are 680 Ohm on the positive board.

R17 and R21 are empty on the positive board and 2.2k Ohm on the negative board.

You left out the volume control on the negative board. What do I have to connect to accomplish the blue connections you drew in?

I somehow managed to fill right hole of R7 with solder. Is that a problem?
_20190814_184852.JPG
 

solderdude

Major Contributor
Joined
Jul 21, 2018
Messages
2,134
Likes
3,418
Location
The Neverlands
Some more questions:
No diodes on the negative board? (LED?)
How do I know if Q2 is still working and functioning? It was really hard to solder Q2 to the board, because it does not want to take any solder to make a solid solder joint.


What about R19 and R23 on the negative board? R19 & R23 are 680 Ohm on the positive board.

R17 and R21 are empty on the positive board and 2.2k Ohm on the negative board.
On the negative board ONLY the parts shown in the schematic I posted must be placed.
All the other parts that are not in that schematic do not need to be placed !

To test Q2 you will have to power up the board with U1, U3 and U4 NOT inserted and measure the voltages on C8 and C9.

You left out the volume control on the negative board. What do I have to connect to accomplish the blue connections you drew in?
You have to place 2 jumper wires where the red stripes are shown
potmeter.png
.



I somehow managed to fill right hole of R7 with solder. Is that a problem?
No, R7 is not used anyway.
 

Silou

Active Member
Joined
Oct 5, 2018
Messages
187
Likes
63
IMG_20190815_121908.jpg

Both boards are done. The volume jumpers are installed but not on the picture. What is the next step? Wire the volpot, the power socket, the gain switch and the power switch?
 

solderdude

Major Contributor
Joined
Jul 21, 2018
Messages
2,134
Likes
3,418
Location
The Neverlands
First test the power supply.
U2 must be installed as well as the power switch.
AC must be connected.
Then measure if C8 and C9 have close to 12V on them.

When this is O.K. install potmeter, gain switch and the other opamps.

When the positive board is confirmed to work then it is time to test the negative board.
 

Silou

Active Member
Joined
Oct 5, 2018
Messages
187
Likes
63
The board and the supplied socket have three contacts, but the socket I bought has only two contacts.

Edit: I soldered the stock one to the board for testing
 
Last edited:

solderdude

Major Contributor
Joined
Jul 21, 2018
Messages
2,134
Likes
3,418
Location
The Neverlands
That's because the 3 pin version has a swicth function in the negative line (not used in O2)

The side contact is not used. The pin closest to the board edge = gnd (is the mantel of the connector) and is one of the AC cntacts
The pin most inwards of the PCB is AC in and is the center pin.
In this particular case, as the input is AC, it does not matter how the trafo is connected as long as it is connected to the most outer and most inner pin.
 

solderdude

Major Contributor
Joined
Jul 21, 2018
Messages
2,134
Likes
3,418
Location
The Neverlands
Set MM to DCV and measure the DC voltage across those capacitors only.
If that is deviating from 12V (11.8V is also O.K.) then something is wrong and must be fixed before continuing the build
 

solderdude

Major Contributor
Joined
Jul 21, 2018
Messages
2,134
Likes
3,418
Location
The Neverlands
measure DCV across C4 and C5 (around 20V over each capacitor)
Then measure DCV across C6 and C7 (must be 12V over each capacitor)
Measure DCV across pin4 and pin8 of U2 (must be 24V when the power switch is on)
 
Last edited:

solderdude

Major Contributor
Joined
Jul 21, 2018
Messages
2,134
Likes
3,418
Location
The Neverlands
perfect...

Measure DCV across pin4 and pin8 of U2 (must be 24V when the power switch is on)
Without a power switch or jumper there won't be a voltage here.
 

solderdude

Major Contributor
Joined
Jul 21, 2018
Messages
2,134
Likes
3,418
Location
The Neverlands
So 24V is present on pin4 and pin8 of U2 but there is no voltage present on C8 and C9 ?
 

Similar threads

Top Bottom