Zenmod : Found a sevice manual you posted , (somewhere else here) so got more homework[emoji18]
The preamp is almost ready. Need to put the fets on and build a case.
Replaced the 1000uf with 2200uF (had some new nichicon kg, so why not use) hope i don't screw it up by doing so.
Also had some transformers that i wanted to re-use. Only they are 160va. would not be a problem i think. Only thing i really need to find out is how to connect the 3 transformers. Because i made this fault already here with the aleph 3 ! [emoji15]
I think i need to connect the two windings of each transformer in parallel to the board. (Each channel separate transformer) Am i correct?
Only the small transformer for the volume control. ..it has a gnd in the middle.
Could someone advise me on how to connect the transformer (s) ?
To be sure posted picture of board
The preamp is almost ready. Need to put the fets on and build a case.
Replaced the 1000uf with 2200uF (had some new nichicon kg, so why not use) hope i don't screw it up by doing so.
Also had some transformers that i wanted to re-use. Only they are 160va. would not be a problem i think. Only thing i really need to find out is how to connect the 3 transformers. Because i made this fault already here with the aleph 3 ! [emoji15]
I think i need to connect the two windings of each transformer in parallel to the board. (Each channel separate transformer) Am i correct?
Only the small transformer for the volume control. ..it has a gnd in the middle.
Could someone advise me on how to connect the transformer (s) ?
To be sure posted picture of board
An externally hosted image should be here but it was not working when we last tested it.
What kind of transformers do you have, dual secondary, center tap, secondary voltage, etc?
Your preamp PCB has two locations marked "50V"
and one location marked "15V gnd 15V"
Attach AC there.
and one location marked "15V gnd 15V"
Attach AC there.
I got 2 transformers each with 2 50vac secondairies. And 1 with 2 15vac secondairies. If i understand correctly i need to connect the gnd of the 15v section to the chassis because of the volume pot.
ok
"2 50Vac secondaries" means two separate windings ?
how much VA is that xformer ?
"2 15Vac secondaries" means two separate windings ?
how much VA is that xformer ?
If the 50V X 2 transormers are the 160VA units you mentioned previously then each 50V secondary is 80VA and should be sufficient for one channel. So one 50V winding to one channel and the second 50V winding to the second channel. You end up with a spare transformer.
You didn't specify the VA rating of the 15 VAC transformer. But if it is a dual sec winding then you will have to connect the two secondaries in series creating a center tap.
50VA should be more than enough for the 15V circuit.
You should get plenty of channel separation using a separate secondary for each channel. However you can always parallel the secondaries (for 160VA total)and use a single transformer for each channel. I think its massive overkill though.
either draw exactly what you have , or put link here , if they're commercial pieces
I can't bang ya in da head to read and reply on specific questions , to give us chance to help you
btw. direct paralleling of secondaries is not dangerous only if that's allowed by xformer maker
I can't bang ya in da head to read and reply on specific questions , to give us chance to help you
btw. direct paralleling of secondaries is not dangerous only if that's allowed by xformer maker
Wel zenmod i feel the same, in my opinion i'm beeing very clear, but perhaps to you i'm not. I posted a picture of the board and stated i had 160va transformers. Couldn't be more clear!!!! But you failed to read that.
I failed to say i have transformers with 2 secondairies, but i directly responded to chambermans question about that. If you remember, it was right after you where rolling on the floor. Always very nice for a first reply.
So stating i have 2 50v secondairies i thought it would be obvious. (2 separate windings, but i guess it's not so obvious.)
4 piecies of wire come out. No more no less. If there were more i would specify!!!!
(I allready learned my lesson from earlier friendly replies and was almost afraid to ask, and i still f@#$@#$ it up not saying it had two secondairies)
I know it's a pain in the butt to give advice about the simpelest things!
I'm greatful for the advise you and all the other members here give me, very greatful.
And some advise from me, don't forget you started as a newbie to!!!
I failed to say i have transformers with 2 secondairies, but i directly responded to chambermans question about that. If you remember, it was right after you where rolling on the floor. Always very nice for a first reply.
So stating i have 2 50v secondairies i thought it would be obvious. (2 separate windings, but i guess it's not so obvious.)
4 piecies of wire come out. No more no less. If there were more i would specify!!!!
(I allready learned my lesson from earlier friendly replies and was almost afraid to ask, and i still f@#$@#$ it up not saying it had two secondairies)
I know it's a pain in the butt to give advice about the simpelest things!
I'm greatful for the advise you and all the other members here give me, very greatful.
And some advise from me, don't forget you started as a newbie to!!!
ok now
just one biggie xformer is enough for preamp
one 50Vac secondary to first channel AC input
second 50Vac secondary to other channel AC input
auxiliary voltage - 2x15Vac xformer to appropriate AC input on pcb ; if windings are separate , phase them as per attached tutorial (look at left side of sketch) , to have proper gnd (CT) for that PSU
just one biggie xformer is enough for preamp
one 50Vac secondary to first channel AC input
second 50Vac secondary to other channel AC input
auxiliary voltage - 2x15Vac xformer to appropriate AC input on pcb ; if windings are separate , phase them as per attached tutorial (look at left side of sketch) , to have proper gnd (CT) for that PSU
Attachments
Took some time to think and read. Here is a picture of the transformer . (I got two 15v transformers. One is 50va the other 80va. Not decided wich one to use. Both are same make so have same lay-out . Picture is of the 50va)
So if i tie blue and yellow together the voltage doubles.
If i connect blue and yellow to ground it creates a center tap and the voltage is back to 15v again?
If this is correct, do i connect it to gnd of the board or should i make a star like ground on the chassis and then connect this to gnd on the board. the "building guide" (some crap paper) says gnd on the board needs to go to the chassis/front plate because the volume pot is there.
So if i tie blue and yellow together the voltage doubles.
If i connect blue and yellow to ground it creates a center tap and the voltage is back to 15v again?
If this is correct, do i connect it to gnd of the board or should i make a star like ground on the chassis and then connect this to gnd on the board. the "building guide" (some crap paper) says gnd on the board needs to go to the chassis/front plate because the volume pot is there.
you are correct. yellow and blue goes to the GND on the board.
but i don't see how the input selector unit should have 15-0-15V.
there is a single LM7812 regulator. and there is no LM7912 regulator. so only a single rail supply. you dont have a schematic of this section?
but i don't see how the input selector unit should have 15-0-15V.
there is a single LM7812 regulator. and there is no LM7912 regulator. so only a single rail supply. you dont have a schematic of this section?
Here you go audiosan
Edit: It is for the volume control. It uses relais.
An externally hosted image should be here but it was not working when we last tested it.
Edit: It is for the volume control. It uses relais.
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