D-AOC PCBs - the building and help Thread

[Potato Cakes]

thx!
anyone else has experimented differents leds or resistors?

Volker did a full write up on this with measure data/fancy graph. It's in this thread. It should answer your question thoroughly.

Thanks!

Paul

 

[OneRoomStudio]

Finally got this one done with some machining/wiring help from a friend.

 

[petermontg]

Hi guys I have an old DAOC here that has a 120hz area problem

When idle it sits -90db but raising the volume raises the noise.

Problem is apparent in both channels.

I've changed the torodial and many grounding schemes.i am missing some voltage around the tube mostly 40odd at the 82 nearest to I/o

Tbh am starting to scratch my head here any input would be appreciated.

 

[petermontg]

Problem solved replaced B+ regulator and grounded the casing of the alpha pots.

Happy days!!!

 

[[silent:arts]]

Thanks for reporting back  8)

 

[AD797]

I am having serious trouble  with the last steps of my d-aoc. So far its running, voltags are looking good. Unit passes audio, input works like expected. The problem appears with the 500k pots/switches. I got some pre soldered switches from ebay and to be honest i don´t get them. Can someone please guide me how to connect the switch propper?

Thank you!

https://abload.de/image.php?img=img_20191003_1535241tkle.jpg
https://abload.de/image.php?img=img_20191003_153405rdk70.jpg
https://abload.de/image.php?img=img_20191003_153532wjkbf.jpg

 

[AD797]

omg, forgett about this... sometimes...

 

[AD797]

Ok, all pots in place and working. right now i use a ll1521 at the input and output is transistorless.  Seem i build a filter too
Strong high boost and lack of bass. Any ideas?

 

[weiss]

Ok, all pots in place and working. right now i use a ll1521 at the input and output is transistorless.  Seem i build a filter too
Strong high boost and lack of bass. Any ideas?

I had the same problem once with my lundahls. Did you wire the transformers correctly?

 

[AD797]

problem apaears also when i am without transformer at all...

 

[weiss]

problem apaears also when i am without transformer at all...

Ah okay. Hobbyist had the same problem back then. Seems like it occurred because of bad grounding.. did you check that?

 

[AD797]

ha, youre right, my unbalanced cabling was just not correct. unit is now unbalanced and workes propper and sounds huuuughe!
just my meters are crazy... needle is dancing but at the other side like in a gssl. strange...

 

[AD797]

fixed. last thing...  there is some high frequent whir very down at around -120. guess i have to exchange my just twisted cables with shielded ones...

 

[weiss]

ha, youre right, my unbalanced cabling was just not correct. unit is now unbalanced and workes propper and sounds huuuughe!
just my meters are crazy... needle is dancing but at the other side like in a gssl. strange...

glad it worked out!

fixed. last thing...  there is some high frequent whir very down at around -120. guess i have to exchange my just twisted cables with shielded ones...

yeah maybe. did you rack it?

 

[AD797]

its already in a case...

 

[AD797]

Someone test the LL1531 Input Transformer here?

 

[Potato Cakes]

Hello, Everyone,

After a couple of years of this sitting around, I am now nearing completion of gathering all of the parts needed and finally worked out resistors values to use in stepped switches for the 100k and 500k log pots. The last thing I haven't yet to decide is the output transformer. I thought about the high nickel CAPI versions, but the primaries at 75ohm and BOM lists one that is 10k:600R. Is there a way to add some sort of resistor array from the PCB to the transformer to balance the impedances or is this a characteristic inherent to the transformer that can't be externally manipulated?

Thanks!

Paul

 

[[silent:arts]]

10K : 600R impedance ratio ≈ 4 : 1 turns ratio.
The 2503 transformer can be wired in 3 : 1.

 

[Potato Cakes]

10K : 600R impedance ratio ≈ 4 : 1 turns ratio.
The 2503 transformer can be wired in 3 : 1.

I guess what throws me off is thinking of the transformer windings with resistance values instead of winding ratios. I'll give ones from Jeff a go.

Thanks!

Paul

 

[Potato Cakes]

Is there a guide for the wiring the CW/Wiper/CCW for the 100k and 500k pots? Did I overlook it in this thread?

Thanks!

Paul