SE Electronics Z3300a
- Thread starter TornadoTed
- Start date
Help Support GroupDIY Audio Forum:
I have in stock : 2SA1015 (I use a pair in my Schoeps circuits) &
I found ;
J310 IDSS 4mA / 2N5486 6,6mA
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BC556 hFE 327 Vbe 665mV / 2N5087 hFE 313 Vbe 660mV /
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In order to be able to repair the defective microphone, he must compare it with the good one.44v is still within the stated specs of the SC1100, as well as the Z3300A, so... What's the actual problem?
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?
???
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)
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...
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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"...
So we have one working SC1100, and one non-working one. The working one still works fine with the UA-25EX, correct?
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...
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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?
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
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...How about you still measure that voltage, hmm?
Here I am now
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...
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...
