SE Electronics Z3300a

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There, that wasn't so difficult now, was it?

So that's with both transistors on the DC/DC board removed, right?
 
There, that wasn't so difficult now, was it?

So that's with both transistors on the DC/DC board removed, right?
Yes
And look what I have found : the + & - were "glued" by short-circuit :rolleyes:
and for what I can see (quite impossible to send a pict 'cause it's so small) there has been a short-circuit for sure (one can see the cooper of the 2 wires)
I have to change these two wires...
 

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Yeah, you're right, but what could have been the damage ??? I think I'll be able to put back the transistors (if they didn't suffer)

Zero f**ks given during assembly? And/or the previous owner "took a look" very very carelessly...
 
Zero f**ks given during assembly? And/or the previous owner "took a look" very very carelessly...
One or the other but not me !
The mic was ok for a couple of hours. I did audio tests oon my last quad tube mic pre... and suddenly it gave up with crackling noise (see the spectrum I recorded)
I opened it AFTER it was OOO (Out Of Order)
 

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I opened the XLR to measure :
mic connected : 1,96v btw pins 2 and 1 / mic disconnected : 44,24v btw pins 2 and 1
there's a short-circuit somewhere, no ? or is it the transfo ?
 
Is that NOW, after you replaced those damaged wires?
No I didn't replace them yet, just push them appart to end this possible (surely) short-circuit... but since it's the same situation I believe something is damaged... (remember the 2 tr are desoldered)
 
The microphone gave up yesterday, so:
1) I opened it to take measurements, mainly at the input of the DC/DC card and I noticed a voltage of 1.9v
2) I did the same measurement as the one that works and I found 24v
3) I came to talk about it on the forum
4) after a few discussions, micolas advised me to change the 2 original transistors with equivalent values (see his post above)
5) I opened the microphone (once again) to de-solder them

6) I opened the microphone tonite (once again) to take measurements (once again) and also photos (at your request) and that's when I noticed 2 problems:
- the inductor wire which was wandering on a track (I cut it)
- the 2 power supply wires short-circuited
Here we are now...
 
SERIOUSLY??? :oops: 🤦‍♂️ 🤦‍♂️ 🤦‍♂️ 🤦‍♂️ 🤦‍♂️



Well, how the hell do you expect to get any audio, with the capsule not getting any voltage? :rolleyes:
When I discovered that the circuit was fed by only 1,9v I stopped expecting any sound... and localize (or so) taht the problem had to do with voltage alimentation
 
May I suggest something ?
Now we know where we are and have identified a real problem (voltage) can we concentrate on :
- what damage could this short have done ?
- how to try to fix this mic
 
Ok, good, finally. Are the two transistors from the DC-DC board, still removed?

Is the voltage between the red wire and ground, still unusually low?
 
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