Peranders
An update and continued problems.
The pre-amp circuit that I'm trying to power with the SSR03 is the MC high impedance version published in linear audio by Joachim Gerhard.
Whilst I had the pre-amps powered by my bench supply I took the opportunity to set the voltage across the input JFETS, these are confirmed genuine parts, and was able to set a stable voltage.
I then hooked up the pre-amps to the SSR03 one at a time. All seemed fine, the positive and negative rails settled at the unloaded SSR03 voltages but it took about one minute.
I then tried both pre amp boards at the same time and trouble raised it's head again, it appears that neither the positive nor negative regulators will start, I tried removing the supply filter caps from both boards, 1000uF but it made no difference, neither positive nor negative regulators will start, output is only a nominal 4 volts on both rails.
I have absolutely confirmed that all resistor values are as per the 12V LM431 BOM to within .01%, I even changed R35 and its negative regulator equivalent to your recommended value of 500 ohms since the associated voltage divider resistors are both 1K ohm per the BOM.
Clearly the regulator does not like the load that the pre-amps represent.
I checked some voltages as follows, at the input to the pre-regulators it is at +/-22 volts unloaded and drops to about +/- 21 volts when loaded with one pre-amp board.
The pre-regulator output voltages are a nominal 13.45 when unloaded but, as expected with the regulator not starting, when loaded I measure only about 4 volts at control pin and that matches the output. There is no measurable voltage drop across the output transistors.
Suggestions?
Can I assume you have seen the circuit for the Gerhard MC Pre-amp.
An update and continued problems.
The pre-amp circuit that I'm trying to power with the SSR03 is the MC high impedance version published in linear audio by Joachim Gerhard.
Whilst I had the pre-amps powered by my bench supply I took the opportunity to set the voltage across the input JFETS, these are confirmed genuine parts, and was able to set a stable voltage.
I then hooked up the pre-amps to the SSR03 one at a time. All seemed fine, the positive and negative rails settled at the unloaded SSR03 voltages but it took about one minute.
I then tried both pre amp boards at the same time and trouble raised it's head again, it appears that neither the positive nor negative regulators will start, I tried removing the supply filter caps from both boards, 1000uF but it made no difference, neither positive nor negative regulators will start, output is only a nominal 4 volts on both rails.
I have absolutely confirmed that all resistor values are as per the 12V LM431 BOM to within .01%, I even changed R35 and its negative regulator equivalent to your recommended value of 500 ohms since the associated voltage divider resistors are both 1K ohm per the BOM.
Clearly the regulator does not like the load that the pre-amps represent.
I checked some voltages as follows, at the input to the pre-regulators it is at +/-22 volts unloaded and drops to about +/- 21 volts when loaded with one pre-amp board.
The pre-regulator output voltages are a nominal 13.45 when unloaded but, as expected with the regulator not starting, when loaded I measure only about 4 volts at control pin and that matches the output. There is no measurable voltage drop across the output transistors.
Suggestions?
Can I assume you have seen the circuit for the Gerhard MC Pre-amp.
Notice that you have current limitation. You may remove it or increase the limit. Notice also that you have resistors in series with the smoothing caps. You may be forced to adjust those resistors also but a good start is to determine how much you load consumes.
You should have 2.5 V across the series transistor, meaning 14.5 V at the collector down to ground.
You should have 2.5 V across the series transistor, meaning 14.5 V at the collector down to ground.
Last edited:
Peranders,
Went through my files, could only find the base and variant pdf's for the SSR03. Went to the website, which I have done before, and yes I had missed the current limiting section so thank you for your patience.
I've not had a chance to make the changes to increase the current limit yet, had a long day, but current limiting explains all my problems, definitely a mia-culpa.
I am curious as to why in all the variants the schematic show a current limit of 295 mA but in the base version with adjustable output the current limit is effectively 687 mA. (2.2 ohms in parallel with 1.0 ohm as the current limit "sense" resistor)
Thanks again for your patience and help.
Went through my files, could only find the base and variant pdf's for the SSR03. Went to the website, which I have done before, and yes I had missed the current limiting section so thank you for your patience.
I've not had a chance to make the changes to increase the current limit yet, had a long day, but current limiting explains all my problems, definitely a mia-culpa.
I am curious as to why in all the variants the schematic show a current limit of 295 mA but in the base version with adjustable output the current limit is effectively 687 mA. (2.2 ohms in parallel with 1.0 ohm as the current limit "sense" resistor)
Thanks again for your patience and help.
(Or plans for another run?
Yes, but I don't support it and won't give any detailed instructions because it's too easy to destroy the pcb. Study closely what the difference is between the positive and the negative half.
http://www.diyaudio.com/forums/grou...per-regulator-power-supply-9.html#post4156303
http://www.diyaudio.com/forums/grou...per-regulator-power-supply-9.html#post4156303
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.