Paradise Builders

diyAudio Chief Moderator
Joined 2002
Paid Member
And here with a 3rd 2SA version that is very lightly compensate, phase max at 63deg (very good) :)

Random 2SA1930/2SC5171 as used in the non oscillating PSU... 2 NPN & 1 PNP traces.
 

Attachments

  • Snap 2013-03-16 at 16.01.17.png
    Snap 2013-03-16 at 16.01.17.png
    63.3 KB · Views: 351
diyAudio Chief Moderator
Joined 2002
Paid Member
They are available at Mouser I saw, not NOS yet. Me I had those from when I was collecting various VAS grade BJTs. Because plastic enclosed too, I thought they might solve the PSU oscillation pain in this kit after weighing the problem, still without Silpads and blind tare dangers given the peculiar sink situation. So it worked. But remember, in combination with "delete the 1uF capacitors parallel to the phono electrolytics". So I hope I contributed a little good practical idea.
 
I would first look if the transistors are stuffed right. It also happened to me that i swapped NPN with PNP.
Leds can be the wrong way around, so can elcaps.

That does not seem to be the case... I have D45H11, D45H11, 11P06, 20N06, D44H11, D44H11.... all alcaps, diodes and leds are positioned correctly (if the silkscreen is correct).

I am using the parts from the GB, but used J310's instead of the J109's supplied by the GB... are there any known 'wrong' parts in the GB or 'errors' in the silkscreen (e.g. I have to turn the legs of transistors etc)?
 
Yep... All seem correct (at least on visual inspection)... I could start replacing transistors, but the strange thing is that I get the same behavior on both boards... So most likely errors would be stuffing error, part selection/GB error, or pcb error (which can be ruled out).

Edit: another option is a problem in the preregulator, however it is 21v 30va transformer with a simple C filter (actually 18 x C per channel) which I had lying around. It is providing 29V plus and minus.... Seems all correct
 
PCB error can be out
Really cek all components again I did cek mine 3 times before soldering and a few more time while building it and still ended up with a capacitor the wrong way around that toke hours to find.

Did you measure the transistors and J fets before soldering?
Maybe a duff one there?