SE Electronics Z3300a

[micolas]

D2 gives 17,20v
D2 + D1 give 25,85v

in the good microphone it is about 27v

 

[Emmathom]

So I leave R13 & R14 as they are (27KΩ) and I put in serie between the 2 diodes a red led anode > cathode

 

[micolas]

in the good microphone it is about 27v

If Uphantom=48v
D1+D2 > 27,**v

 

[micolas]

So I leave R13 & R14 as they are (27KΩ) and I put in serie between the 2 diodes a red led anode > cathode

Oui Monsieur
3mm Red LED

 

[micolas]

Larger diameter LEDs work at higher voltages

 

[micolas]

Then measure the polarization voltage of the capsule

 

[micolas]

So I leave R13 & R14 as they are (27KΩ) and I put in serie between the 2 diodes a red led anode > cathode

if you don't get +/- 57v,
gradually reduce R13 as you did before

 

[Emmathom]

Fine.
1) I'm gonna feed the 48v from my Presonus to verify the voltages (at my desk = Edirol USB powered)
2) got find a 3mm red led (got one or two somewhere... but where ??)
3) will install it as you said

 

[micolas]

Fine.
1) I'm gonna feed the 48v from my Presonus to verify the voltages (at my desk = Edirol USB powered)
2) got find a 3mm red led (got one or two somewhere... but where ??)
3) will install it as you said

Do you remember how many discussions there were about the difference in Phantom voltage from 48v to 44v.
Now I think you understand what I was talking about, why we insisted on working correctly, at standardized values, because 2..4v can make a difference, in DC/DC and BIAS of jFET too.

 

[Emmathom]

Here are the values with 48v Presonus :
Pin 2 = 38,79v / Pin 3 = 38,87v / D2 = 17,20v / D2+D1 = 28,24v / R18 = +56,02v / R19 = -56,04v / before R5 = 32,81v / after R5 = 20,55v / Fet D = 15,85v / Fet S = 0,36v / SA1015 e = 2,82v / K105 D = 28,10v / K105 S = 8,17v
(no led in serie with the zeners / no R in // with R13)

 

[micolas]

Here are the values with 48v Presonus :
Pin 2 = 38,79v / Pin 3 = 38,87v / D2 = 17,20v / D2+D1 = 28,24v / R18 = +56,02v / R19 = -56,04v / before R5 = 32,81v / after R5 = 20,55v / Fet D = 15,85v / Fet S = 0,36v / SA1015 e = 2,82v / K105 D = 28,10v / K105 S = 8,17v
(no led in serie with the zeners / no R in // with R13)

R13= 0 ohm or 27k ?

 

[Emmathom]

R13= ?

27KΩ original value

I agree now that 4v on phantom change a lot ! but how to deal with a sound-card powered by USB ? it's a bad engineering !

 

[micolas]

Here are the values with 48v Presonus :
Pin 2 = 38,79v / Pin 3 = 38,87v / D2 = 17,20v / D2+D1 = 28,24v / R18 = +56,02v / R19 = -56,04v / before R5 = 32,81v / after R5 = 20,55v / Fet D = 15,85v / Fet S = 0,36v / SA1015 e = 2,82v / K105 D = 28,10v / K105 S = 8,17v
(no led in serie with the zeners / no R in // with R13)

you have to put LEDs in series
if you can't find it, put it in the same way, but 2..3 1n4148 diodes in series with the 2 zenner, checks, and measure again
Respect the polarity

 

[micolas]

how does the Orig microphone measure up to the Presonus?

 

[Emmathom]

you have to put LEDs in series
if you can't find it, put it in the same way, but 2..3 1n4148 diodes in series with the 2 zenner, checks, and measure again
Respect the polarity

I found a red led 3mm

 

[micolas]

R2 and R3 must be matched better
Upin2xlr = Upin3xlr

 

[Emmathom]

R2 and R3 must be matched better
Upin2xlr = Upin3xlr

0,08v... not enough ?

 

[micolas]

0,08v... not enough ?

No

 

[micolas]

Is your DMM auto-scaled or do you manually switch the measurement range?

 

[Emmathom]

OK 0,08v is too much... but does the other voltages influence on Pin 2&3 ? Yes is the answer...
Sorry but I have an appointment right now : I'll be back in an hour and back to work on this...