using this schematic: http://diyforums.org/SSMH/variants/SSMH-12AU7.gif
Originally Posted by doors666
1. Is there an error on the 12au7 schematic. why is c1 coming before r13 but c6 is coming from after r13, wont r13 act as a charging resistor for C6. Is this there on pcb also.
R13-C6 form a filter, reducing PS noise for the low current stages.
2. There is no earth with the psu, should I use 0v for chassis earth also.
4. do i need to insulate the rcas, headphone out, pot from the chassis.
6. can chassis ground point be used as a star ground.
2. you can connect the chassis to 0V (at only one point preferably).
4-6. not knowing how the pcb is setup, I'll let someone else answers that.
3. does this psu have overcurrent protection. Couldnt find a datasheet on the web.
It would seem so, reading this, "The power supply current limit cycles"
5. which are good places for carbon film resistors and which are for metal film.
r14-r15, r3-r9 are best carbon film, all others can be metal. But you'll probably have no trouble with using all metal film.
7. Can i safely leave out the pot and control the volume from my B1 preamp.
If you do that, you need to wire a 50k resistor from the junction of r16-r14 to ground (same for the other channel)
9. which caps. can i use:
220uf panasonic FC and FM, Elna RE-3 – which is the best option. Does it help to bypass this with a film cap of say 10-15nf
680uf, 63v – I only got Nichicon PW with this rating, Is it good enough or should I look for something else. Does it help to bypass this with a film cap. I also have 1000uf, 100v Nichicon PJ, can the psu handle this.
470, 63v – only got UCC LXZ. Is it good enough or should I look for something else.
220nf – got wima mkp2 and mks4. I guess mkp2 wins.
- 220uf: panasonic FC or FM. In this application, both are good enough (better than the Elna).
- 680uf: the nichicon are fine
- 470uf: the UCC are good (same league as the panasonic)
- 220nf: mkp is usually a bit better.