Greetings from the Colorado mountains. I have reclaimed a microphone collection of mine that's been in storage for about 25 years. I've just started to go through them to make certain that they still work, and possibly replace some old parts. Some questions for the working recording engineers and audio professionals;
1. Philosophy: I have started with my AKG C-12 power supply & pattern box. All the PS caps seem fine, but there's a Selenium rectifier and a point contact diode that for reliability's sake, I'd replace, and possibly the caps too. I'd have to adjust the rectifier's output to compensate for lower Vf drop with silicon devices.
The question is, would a buyer in today's market prefer an original kit that works for an unknown time, or an updated, more reliable version? Of course, there will always be arguments about changing the sound even if identical value caps are used and the voltages maintained...
2. I did find a C-12 schematic , but no resistor values for the pattern box. I'd like to check them but most will require desoldering to view their values. They are of the crimped end cap type and I don't want to move them either. Does anyone have these values (and schematic)? Then, I can do a simple resistance measurement.
3. Finally, there is a 2 uF cap from pin 3 to ground (see attached schematic). The top of the cap is in series with a 1M2 resistor to the switch wiper and also goes to one side of the capsule via a 30 M resistor, with a 5000pF cap to ground. I'm not sure I understand what the function of this NP electrolytic cap is and would really appreciate help!
Many thanks,
Ivan
1. Philosophy: I have started with my AKG C-12 power supply & pattern box. All the PS caps seem fine, but there's a Selenium rectifier and a point contact diode that for reliability's sake, I'd replace, and possibly the caps too. I'd have to adjust the rectifier's output to compensate for lower Vf drop with silicon devices.
The question is, would a buyer in today's market prefer an original kit that works for an unknown time, or an updated, more reliable version? Of course, there will always be arguments about changing the sound even if identical value caps are used and the voltages maintained...
2. I did find a C-12 schematic , but no resistor values for the pattern box. I'd like to check them but most will require desoldering to view their values. They are of the crimped end cap type and I don't want to move them either. Does anyone have these values (and schematic)? Then, I can do a simple resistance measurement.
3. Finally, there is a 2 uF cap from pin 3 to ground (see attached schematic). The top of the cap is in series with a 1M2 resistor to the switch wiper and also goes to one side of the capsule via a 30 M resistor, with a 5000pF cap to ground. I'm not sure I understand what the function of this NP electrolytic cap is and would really appreciate help!
Many thanks,
Ivan