Leestereo
Super Member
AK member "ragstoriches" brought in a very nice Marantz 2325 for some restoration and upgrade work.
The restoration/upgrade included the following:
1. Replacement of the power supply electrolytic capacitors with low ESR types (increasing capacity where appropriate and physically possible).
2. Replacement of the signal path electrolytic capacitors with film types (whenever possible) or bi-polar electrolytic types.
3. Upgrade original polyester film capacitors to polypropylene film types (as appropriate).
4. Replacement of the signal path ceramic capacitors with C0G types.
5. Replacement of the failure-prone 2SC458 and 2SA722 transistors.
6. Replacement of the output relay.
Power Supply & Relay Board (P800)
The P800 board contains the regulated power supplies as well as the protection circuit.
P800 board in original state
Components removed
Board cleaned of glue residue
Restored and upgraded board
The DS-131B dual diodes, H808 and H809, were upgraded to high current, soft recovery types:
NXP BYQ28E-200,127. The capacitor C803 is the main filter for the regulated supplies and the original 470µF/63V capacitor was replaced with a 1200µF/63V low ESR type. Similarly, capacitor C806 filters the 35V and 19V supply, and the original 220µF/63V capacitor was replaced with a 680µF/63V low ESR type. The large 150 ohm/5W dropping resistor, R801, that feeds C804, was replaced with a physically smaller 150 ohm/7W one to allow better air flow around the surrounding components. The C804 capacitor that filters the 14V supply was replaced with a 680µF/63V low ESR type. Capacitors C805, C807 and C809 are on the base of the regulator/pass transistors and were replaced with low ESR types: 470µF/35V, 330µF/50V and 22µF/50V, respectively.
Capacitors C811, C812 and C813 are used in the protection relay circuit and were also replaced with low ESR types: 22µF/63V, 47µ/25V and 220µF/35V, respectively. The protection relay (L801) was replaced with an OMRON LY2-0-DC24, which is a drop-in replacement for the original type.
The restoration/upgrade included the following:
1. Replacement of the power supply electrolytic capacitors with low ESR types (increasing capacity where appropriate and physically possible).
2. Replacement of the signal path electrolytic capacitors with film types (whenever possible) or bi-polar electrolytic types.
3. Upgrade original polyester film capacitors to polypropylene film types (as appropriate).
4. Replacement of the signal path ceramic capacitors with C0G types.
5. Replacement of the failure-prone 2SC458 and 2SA722 transistors.
6. Replacement of the output relay.
Power Supply & Relay Board (P800)
The P800 board contains the regulated power supplies as well as the protection circuit.
P800 board in original state
Components removed
Board cleaned of glue residue
Restored and upgraded board
The DS-131B dual diodes, H808 and H809, were upgraded to high current, soft recovery types:
NXP BYQ28E-200,127. The capacitor C803 is the main filter for the regulated supplies and the original 470µF/63V capacitor was replaced with a 1200µF/63V low ESR type. Similarly, capacitor C806 filters the 35V and 19V supply, and the original 220µF/63V capacitor was replaced with a 680µF/63V low ESR type. The large 150 ohm/5W dropping resistor, R801, that feeds C804, was replaced with a physically smaller 150 ohm/7W one to allow better air flow around the surrounding components. The C804 capacitor that filters the 14V supply was replaced with a 680µF/63V low ESR type. Capacitors C805, C807 and C809 are on the base of the regulator/pass transistors and were replaced with low ESR types: 470µF/35V, 330µF/50V and 22µF/50V, respectively.
Capacitors C811, C812 and C813 are used in the protection relay circuit and were also replaced with low ESR types: 22µF/63V, 47µ/25V and 220µF/35V, respectively. The protection relay (L801) was replaced with an OMRON LY2-0-DC24, which is a drop-in replacement for the original type.