A question about C6 on BrianGT's Mini-A board.
Can the value of C6 (presently 47nF) be increased in order to quell more noise from the zener at Z5. If so, how much?
Thanks.
George
Can the value of C6 (presently 47nF) be increased in order to quell more noise from the zener at Z5. If so, how much?
Thanks.
George
Here you should find some hints:
http://www.diyaudio.com/forums/showthread.php?postid=152250#post152250
http://www.diyaudio.com/forums/showthread.php?postid=152250#post152250
Thanks, Dave.
Unfortunately, it turns out that I only have room for a .01uF, but at least I doubled the value.
George
Unfortunately, it turns out that I only have room for a .01uF, but at least I doubled the value.
George
Another question.
I can save a good bit of wire and not insubstantial "path length" by taking my output board V+ and V- directly from my PS board output taps. Is there any reason not to do so?
Thanks.
George
I can save a good bit of wire and not insubstantial "path length" by taking my output board V+ and V- directly from my PS board output taps. Is there any reason not to do so?
Thanks.
George
Progress!
Finished! Will try to find fitting terminal blocks for the AC inputs.
Nearly there. Still to do:
An externally hosted image should be here but it was not working when we last tested it.
Finished! Will try to find fitting terminal blocks for the AC inputs.
An externally hosted image should be here but it was not working when we last tested it.
Nearly there. Still to do:
- buy & install matched Q1 and Q2
buy & install C4
wait for & install R0
install Q6 and Q7
Hi Beftus !
One 220µF/35V cap is in wrong position (+/-).
The one concerned is on the left side, according to your pic.
This has been pointed in the Mini-A thread.
Reverse the polarity...😉
One 220µF/35V cap is in wrong position (+/-).
The one concerned is on the left side, according to your pic.
This has been pointed in the Mini-A thread.
Reverse the polarity...😉
I have read that in the first batch of BrianGT's PCBs indeed there was a polarity error regarding C1 that since has been corrected.
This is my source: http://www.diyaudio.com/forums/showthread.php?s=&postid=1200890&highlight=#post1200890
So if you don't mind I think I'll leave it in for the moment. I might even contact BrianGT to be sure.
This is my source: http://www.diyaudio.com/forums/showthread.php?s=&postid=1200890&highlight=#post1200890
So if you don't mind I think I'll leave it in for the moment. I might even contact BrianGT to be sure.
Korben69, this comes straight from the horse's mouth (BrianGT):
Many thanks to BrianGT for clarifying the issue.
Many thanks to BrianGT for clarifying the issue.
Great answer Beftus ,thanks to Brian !
My mistake, I've got black boards, BTW I've to desolder this cap.
I'll try to ship your 2x3R this week.
Seems they are awaited... I'm looking for 2 terminal blocks 7.5mm for the PSU board 😉
My mistake, I've got black boards, BTW I've to desolder this cap.
I'll try to ship your 2x3R this week.
Seems they are awaited... I'm looking for 2 terminal blocks 7.5mm for the PSU board 😉
korben69 said:
Will be looking forward to them, thanks!
Terminal blocks you say? I'm looking for terminal blocks too... I ordered terminal blocks for all inputs and outputs and was unpleasantly surprised that the AC inputs aren't 5mm spacing. 😡
I've held a white coloured terminal block last weekend but wasn't sure it had the right lead spacing and if it would fit without interfering with the LED diode and the rectifier heatsinks. I'll have to bring my PSU PCB with me to see if they will fit. If they fit the PSU board I'm more than willing to supply you. 🙂
Member
Joined 2002
Progress report for my MiniA PSU, tested today.
Configuration
Transfo : Antek 3212 / 300Va 2x12V (12.34)
Diodes : MUR 1560
Caps : 3x12000/63v per rail
Bleeder Resistors : 3.3K/3W
1 x 0R47/3W on each rail
About 16.58v at the output with no load on both +/-
Cut-off frequency : 28.22Hz (Thanks Beftus 😉 )
Seems to be fine, any opinion ?
I agree with Jleaman : Q1-Q2-Q3 should be matched...
Configuration
Transfo : Antek 3212 / 300Va 2x12V (12.34)
Diodes : MUR 1560
Caps : 3x12000/63v per rail
Bleeder Resistors : 3.3K/3W
1 x 0R47/3W on each rail
About 16.58v at the output with no load on both +/-
Cut-off frequency : 28.22Hz (Thanks Beftus 😉 )
Seems to be fine, any opinion ?
I agree with Jleaman : Q1-Q2-Q3 should be matched...
albertli said:
I'm not an expert but it seems to be too high using common values.
Your 18V transfo, 400Va, will be well suited for a F5.
jleaman said:
The spreadsheet doesn't mention Q3, only that "Q1 and Q2 should have matched VGS". What's the deal here?
Only Q1 and Q2 need to be matched because they are the differential pair. Q3 is the constant current source which doesn't need to be matched. Of course, no one will say fault if you want to match all 3 🙂
pchw said:
A quick search around some documentation (like the Aleph 3 service manual) "out there" indeed yields that Q1 and Q2 together form the differential input pair and hence must be matched.
Thanks!
