SE Electronics Z3300a

[Emmathom]

Wow do not quarrel guys ! I thank both of you for your help...

 

[Emmathom]

@Emmathom
Instead of speculating, replace both transistors in the DC/DC converter of the faulty microphone
jFet: any N-Channel with Idss 4...8mA
BJT: any PNP with hFE 200..400
and see what happens.

I have in stock : 2SA1015 (I use a pair in my Schoeps circuits) & J305 : would that fit ?

I found ;
J310 IDSS 4mA / 2N5486 6,6mA
----
BC556 hFE 327 Vbe 665mV / 2N5087 hFE 313 Vbe 660mV /

 

[Emmathom]

I desolder the bjt and the fet...
they both seem ok regarding to my Tr testeur

K105 : IDSS 13mA / Id 0,86mA / Vg 594mV
C1008 : hFE 169 / Ie 1,3mV / Vbe 590mV

so now, what should I do ?

 

[micolas]

44v is still within the stated specs of the SC1100, as well as the Z3300A, so... What's the actual problem?

In order to be able to repair the defective microphone, he must compare it with the good one.
2 microphones must be simultaneous connected to the Edirol interface which without load delivers a phantom voltage of 44v.
I want to help him, I have 2 sc1100 and a z3300, with a interface with phantom voltage of >48v.
What tensions can I tell him in the relevant points?

 

[Emmathom]

I desolder the bjt and the fet...
they both seem ok regarding to my Tr testeur

K105 : IDSS 13mA / Id 0,86mA / Vg 594mV
C1008 : hFE 169 / Ie 1,3mV / Vbe 590mV

so now, what should I do ?

???
I took this occasion to cchange the 1nF (between the 2 1GΩ) for a WIMA Fkp2 and the 47uF 25v by a Panasonic same value... and cleaned the two circiuts with isop. alcool for the 2nd time (they were dirty)

 

[micolas]

I have in stock : 2SA1015 (I use a pair in my Schoeps circuits) & J305 : would that fit ?

I found ;
J310 IDSS 4mA / 2N5486 6,6mA
----
BC556 hFE 327 Vbe 665mV / 2N5087 hFE 313 Vbe 660mV /

The jFET must be measured with the Matador method, not with a multimeter.
The ones you have are good, just replace them to eliminate 2 potential suspects. If it does not change, continue with the comparative measurements in as many points as possible from the exit to the entrance.

 

[Emmathom]

The jFET must be measured with the Matador method, not with a multimeter.
The ones you have are good, just replace them to eliminate 2 potential suspects. If it does not change, continue with the comparative measurements in as many points as possible from the exit to the entrance.

I don't know "matador method" I use a Tester I bought on ebay...

 

[Khron]

2 microphones must be simultaneous connected to the Edirol interface which without load delivers a phantom voltage of 44v.
I want to help him, I have 2 sc1100 and a z3300, with a interface with phantom voltage of >48v.
What tensions can I tell him in the relevant points?

Yes, because if one SC1100 works fine with that 44v phantom voltage, but the other one doesn't, surely the interface is to blame, right?

If you really were the technician / experienced person you seem (or at least claim) to be, you'd be aware that +/-10% tolerance in voltages and other parameters is pretty much normal in electronics, especially in discrete circuits like this. Especially since the power to the audio circuit is (likely) zener-regulated, and the DC-DC oscillator board is likely not THAT picky. This isn't even a C414-P48, to require 48v precisely

"Instead of speculating", how about respecting the first commandment of troubleshooting? "Thou shalt measure voltages"...

Hi ! my second SC1100 I bought from second-hand arrived with a pb : no sound and crackling noise when fed by phantom power...
here is the noise recorded...

So we have one working SC1100, and one non-working one. The working one still works fine with the UA-25EX, correct?

I have 2 of them : one is ok and the other worked for a couple of hours and then nothing...
I mesured voltage at the entry of polarisation board (a schematic of z3300 would be great !!!) and the good one has 28v on the first R of the circuit when the "off one" has only 1v... I see a transistor (bjt ?) C1008 • Y-705 and another one labelled K105

Since we have no certain schematics, can you at least take a photo of the inside of the bad SC1100, and indicate where you're measuring 28v on the good mic, and just 1v on the bad one?
Photos of both boards (the audio board & the DC-DC oscillator board) would help, too...

 

[Emmathom]

@Khron : I take the 4 picture, edit them in photoshop and come back in 5mn...
Thank you

 

[Emmathom]

Hi there are the picts : polar-back + polar-front / pre-back + pre-front
One can see the Wima FKP2 1nF instead of the tantalum (or ceramic ?) that was there...
I measured 24v at R15 on polar board

 

[Khron]

Hi there are the picts : polar-back + polar-front / pre-back + pre-front

can you at least take a photo of the inside of the bad SC1100, and indicate where you're measuring 28v on the good mic, and just 1v on the bad one?

 

[micolas]

I don't know "matador method" I use a Tester I bought on ebay...

 

[Emmathom]

look at this shit here !

 

[Emmathom]

This way ?

 

[Emmathom]

Since we have no certain schematics, can you at least take a photo of the inside of the bad SC1100, and indicate where you're measuring 28v on the good mic, and just 1v on the bad one?

I measured 28v at R15 on the polar board...

 

[Khron]

I measured 28v at R15 on the polar board...

What about the good / bad voltage between ground, and the red wire going to that "+" pad on the bottom of the oscillator board?

 

[Emmathom]

What about the good / bad voltage between ground, and the red wire going to that "+" pad on the bottom of the oscillator board?

Now I've de-solder the bjt and the jfet... I think I can't measure anything without them...
So the question is do I put back the ones that were in the mic or do I change them ?
C1008 change to 2N5087 & K105 change to 2N5486

Measured ones (original)
K105 : IDSS 13mA / Id 0,86mA / Vg 594mV
C1008 : hFE 169 / Ie 1,3mV / Vbe 590mV

Measured ones (replacement)
2N5486 6,6mA
2N5087 hFE 313 Vbe 660mV

 

[Khron]

Now I've de-solder the bjt and the jfet... I think I can't measure anything without them...

How about you still measure that voltage, hmm? I don't know about you, but troubleshooting doesn't work based purely on (baseless) assumptions...

 

[Emmathom]

How about you still measure that voltage, hmm? I don't know about you, but troubleshooting doesn't work based purely on (baseless) assumptions...

Khron, I measured these voltages yesterday ! and then micolas told me to change these 2 transistors so I desolder them...
Here I am now

 

[Khron]

He said absolutely nothing about "why" though, did he?

But anyway, especially if you have the mics there, and open, why is it so difficult to measure two voltages??? Or are you really satisfied not knowing anything for sure?
You can probably even see which resistor legs that red wire connects to, on both boards; white wire seems to be ground.

Electronics is a science, and that's why we have measurement tools that we use...