How is this possible because you didn't install Q12 and Q14 ? Or are they on the underside ?
You are lucky then to have the order, I am still waiting, but if you are correct then Q15 and Q16 were not mentioned in the previous errors - hence my request to Marcel to list every component that is affected and what is needed for each to be inserted in the pcb for correct operation.
What is this new issue with Q12 and Q14?
Marcel, you must be very clear on all of this with so many errors.
What is this new issue with Q12 and Q14?
Marcel, you must be very clear on all of this with so many errors.
Also looking at the photo in post #137 where you say it is working, I can spot the following discrepancies on the pcb - there maybe others I can't see.
Caps C14, C15, C2 and C7 not loaded.
Q12 and Q14 are not loaded on the front of the pcb at least.
I can see one resistor linked out.
I can see another resistor not loaded.
Please advise on all of these issues I have raised in this post and the posts above thanks Marcel.
Caps C14, C15, C2 and C7 not loaded.
Q12 and Q14 are not loaded on the front of the pcb at least.
I can see one resistor linked out.
I can see another resistor not loaded.
Please advise on all of these issues I have raised in this post and the posts above thanks Marcel.
I see some other things that needs explaining; No1. On the cathode of Q9 (BD140) is a resistor and a capacitor to earth, R17 and C1. I miss the same set on the cathode of Q10 (BD139). Look at the A15 mk3 and the A18, there you see on both cathodes a resistor and capacitor to earth. I believe we need to install this on these boards. No.2 On the board you see RP1 between Q9 and Q10, I think this should be R44b (1 ohm) according to the file. There is also a RP2 next to C13, I think this should be R39 (47,5 ohm) according to the file. For C7 you can't use a decent size capacitor, there is no room for it. The same for C2, C3, C4. For a good class A amp you want to use optimum parts. Further I must say that everything on the board is very crowded and makes soldering not easy. The board could be bigger to my taste. There are 2 rows for mounting different sorts of mosfets you mentioned earlier on, but in the description there's no mention wich should go where. The boards look fine, but it needs a remake.
Sorry, I forgot to mention that it's not easy to read de component numbers on the boards. It's so small, sometimes I had to use a magnifying glass. The same for the schematic included with the boards are the component numbers hard to read.
Yes the pcb's need to be redone and issued to those of us that have purchased faulty boards,.
We wait on Marcel to list every error, change and modification that needs to be done on these pcb's.
We wait on Marcel to list every error, change and modification that needs to be done on these pcb's.
I see some other things that needs explaining; No1. On the cathode of Q9 (BD140) is a resistor and a capacitor to earth, R17 and C1. I miss the same set on the cathode of Q10 (BD139). Look at the A15 mk3 and the A18, there you see on both cathodes a resistor and capacitor to earth. I believe we need to install this on these boards.
No.2 On the board you see RP1 between Q9 and Q10, I think this should be R44b (1 ohm) according to the file.
There is also a RP2 next to C13, I think this should be R39 (47,5 ohm) according to the file.
For C7 you can't use a decent size capacitor, there is no room for it.
The same for C2, C3, C4. For a good class A amp you want to use optimum parts. Further I must say that everything on the board is very crowded and makes soldering not easy. The board could be bigger to my taste.
There are 2 rows for mounting different sorts of mosfets you mentioned earlier on, but in the description there's no mention wich should go where. The boards look fine, but it needs a remake.
The board is designed fot fets with GSD and GDS pinout. So the Hitachi, Exicon, ALF and Toshiba fets can be used. Care it required to use the appropriate connections.
Caps C14, C15, C2 and C7 not loaded.
Q12 and Q14 are not loaded on the front of the pcb at least.
I can see one resistor linked out. I can see another resistor not loaded.
As a last note: the Bias resistors and R47 are to accomodate the 2SK2220 and 2SJ351. When using the Toshiba, ALF, Hitachi (Renesas) or Exicon fets you may need to tune these resistors as the Yfs and input capacitance can be different,
No.2 On the board you see RP1 between Q9 and Q10, I think this should be R44b (1 ohm) according to the file.
There is also a RP2 next to C13, I think this should be R39 (47,5 ohm) according to the file.
For C7 you can't use a decent size capacitor, there is no room for it.
The same for C2, C3, C4. For a good class A amp you want to use optimum parts. Further I must say that everything on the board is very crowded and makes soldering not easy. The board could be bigger to my taste.
There are 2 rows for mounting different sorts of mosfets you mentioned earlier on, but in the description there's no mention wich should go where. The boards look fine, but it needs a remake.
The board is designed fot fets with GSD and GDS pinout. So the Hitachi, Exicon, ALF and Toshiba fets can be used. Care it required to use the appropriate connections.
Caps C14, C15, C2 and C7 not loaded.
Q12 and Q14 are not loaded on the front of the pcb at least.
I can see one resistor linked out. I can see another resistor not loaded.
As a last note: the Bias resistors and R47 are to accomodate the 2SK2220 and 2SJ351. When using the Toshiba, ALF, Hitachi (Renesas) or Exicon fets you may need to tune these resistors as the Yfs and input capacitance can be different,
So Marcel, how are we supposed to keep up with all of these corrections?
What are we supposed to see in the pcb layout you show in post #148?
What are we supposed to see in the pcb layout you show in post #148?
I’ve spotted a design error in the schematic as well. A 100k resistor needs to be added from pin 2 of the IC to ground to stabilize the servo loop.
I’ve created a new PCB design correcting the errors. I’m willing to absorb 50% of the PCB cost and offer these for 6,75 euro for those that ordered the pcb’s
I’ve created a new PCB design correcting the errors. I’m willing to absorb 50% of the PCB cost and offer these for 6,75 euro for those that ordered the pcb’s
Marcel, I have sent you a PM, I would suggest you get the new pcb's - load them and test to make sure all is well before sending any out.
I take it from your post that the design is now working to your satisfaction?
I take it from your post that the design is now working to your satisfaction?
I’ve auditioned the new A19 today and have to say that it is a big step from the A18.
Best performance was with the Exicon fets over the renesas and the toshiba ones.
Also changed some component values to accommodate power rails upto 40v instead of 25. This improves dynamics.
Best performance was with the Exicon fets over the renesas and the toshiba ones.
Also changed some component values to accommodate power rails upto 40v instead of 25. This improves dynamics.
I agree, still interested in the new boards. I Hope that this version is without faults because I am afraid of using the current boards. According to your last posts you used the 2SK2220 and 2SJ351 and changed some part values. Also that it's possible to go up to 40 volts. Quite interesting. Can you reveal the different part values and so ? Keep up the good work.
