I'd like to rebuild a Marantz 7T that I have acquired. The existing rebuild threads I am seeing seem to be bordering on ridiculous. I recently rebuilt a Hadley 621 with a similar power supply and found it to be quite stable in terms of measured voltage. The design of this pre-amplifier as well as the Hadley 621 appears to be a series-pass fixed voltage regulator. This 7T utilizes a 43V Zener and a transistor for controlling the output voltage. Q601 also functions as a current limiter based on my understanding of this type of regulator. Below, I've copied over the power supply from the schematic.
So far, within the power supply, I plan to:
1) replace all resistors with Vishay CMF and/or RN film resistors.
2) recap using appropriately sized axial caps.
3) replace the full-wave rectifier with uf4007s.
4) replace D602 with a new 43V zener (since there's no 43.6V through-hole zener)
So, my question is what have we learned about power supplies since 1966? Appreciate any help here not based simply on the existing threads on this preamp.
So far, within the power supply, I plan to:
1) replace all resistors with Vishay CMF and/or RN film resistors.
2) recap using appropriately sized axial caps.
3) replace the full-wave rectifier with uf4007s.
4) replace D602 with a new 43V zener (since there's no 43.6V through-hole zener)
So, my question is what have we learned about power supplies since 1966? Appreciate any help here not based simply on the existing threads on this preamp.