SE Electronics Z3300a
- Thread starter TornadoTed
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Help Support GroupDIY Audio Forum:
2,34v btw 1 & 2 / 2,10v btw 1 & 3... and
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Ok the blue ones : will do tomorrow morning (without resolding the Tr I presume...)
Hi Khron, C1 & C2 removed... and stil 1,9v at "+" (the 2 DC/DC transistors still removed)
But Let me suggest that it has to do with the ouput transformer because it's the only component between the XLR (wich porvides 44v when disconnected) and the 2 boards (pre & DC/DC)
But Let me suggest that it has to do with the ouput transformer because it's the only component between the XLR (wich porvides 44v when disconnected) and the 2 boards (pre & DC/DC)
Ok, would you care to explain how, then?
Show me on a schematic, then. We can use the U87 schematic.
http://recordinghacks.com/images/mic_extras/neumann/u87ai-schematic.gif
Neither end of the secondary should have any connection to ground, so unless it somehow ended up short-circuiting to ground internally... Not impossible, just very very VERY unlikely.
How about measuring the two 2.2k resistors between XLR pins 2/3 and the common supply rail (red wire going to the DC-DC board)? Or actually, that whole row of components on the lower edge of the audio board (R1/2/3/4 and L1/2).
And since the wires between the two boards were the way they were i would also check the wires within the transformer "case".
Show me on a schematic, then. We can use the U87 schematic.
http://recordinghacks.com/images/mic_extras/neumann/u87ai-schematic.gif
Neither end of the secondary should have any connection to ground, so unless it somehow ended up short-circuiting to ground internally... Not impossible, just very very VERY unlikely.
How about measuring the two 2.2k resistors between XLR pins 2/3 and the common supply rail (red wire going to the DC-DC board)? Or actually, that whole row of components on the lower edge of the audio board (R1/2/3/4 and L1/2).
And since the wires between the two boards were the way they were i would also check the wires within the transformer "case".
I apologize for interrupting you
With the microphone unpowered, with the secondary of the transformer still soldered to the board, measure the ohmic resistance between the ends of the resistors
R4 and R3 (the ends towards the cylindrical shielding of the transformer).
It must measure a minimum of 43.9 ohms.
With the microphone unpowered, with the secondary of the transformer still soldered to the board, measure the ohmic resistance between the ends of the resistors
R4 and R3 (the ends towards the cylindrical shielding of the transformer).
It must measure a minimum of 43.9 ohms.
Attachments
I've desoldered the DC/DC board and the 3 connexions of the capsule and put the board appart for easy intervention.
I will open up the transformer case and will do now what you asked for (R1/2/etc) and come back to you in a couple of minutes...
I will open up the transformer case and will do now what you asked for (R1/2/etc) and come back to you in a couple of minutes...
Hi micolas, wlcome back
there is 48,4Ω between R3 & R4...you're luckyHi micolas, wlcome back
the transformer secondary is good
De-solder a single end of the resistors
R4 R2 R1 R3
and measure them
and the ohmic resistance of inductors L1 and L2 is 5.2 ohm (do not need to be unsoldered)
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I will (here is a pict where you can read the values)
L1 & L2 (not unsoldered) are 3,5Ω
Attachments
measure equal?
De-solder a single end of the resistors
R4 R2 R1 R3
and measure them
R4 R2 R1 R3
and measure them
Yep
