A few months ago my piano amp was not working at all. I assumed the power supply was faulty. I ordered parts to restore the power supply and amp modules and made the change. It is working fine now. Here is a report of what I did, for the record.
My piano is a 73 suitcase Rhodes Mark I piano ref. 3077. No upgrades have been done on this power supply or on the amplifier modules so far. It was time to change all the electrolytic capacitors. I also changed the twisted wires to suitable 0.5ohm resistors. I did not change the transistors.
You will find a picture of the finished product here. Zoom in for details : https://photos.app.goo.gl/5TqvNPgFRDPxxpE1A
The part list. At the end of each line, what I ended up choosing.
Amp capacitor Electrolytic C1 4,7uF / 25V NP AXIAL >>> Mundorf BG50 4.7uF 75V
Amp capacitor Electrolytic C2 1uF / 16V NP AXIAL >>> Mundorf BG50 1uF 75V
Amp resistor Wirewound R18-R19 R20-R21 0,47 ohm - 5W >>> Royal 0,47 ohm 5W
PSU capacitor Electrolytic C1 C2 1000uF – 35V - 60 mm AXIAL >>> Jamicon 2200uF 35V
PSU capacitor Electrolytic C3 C4 500uF - 15V - 40 mm AXIAL >>> Vishay BC-021 470uF 25V
PSU capacitor Electrolytic C1 C2 11000uF – 40V – diam 50 mm >>> F+T GMB 33000uF 40V
It costed me 52 euros inc. VAT + 8 euros delivery = 60 euros in total ie. US$ 69 in jan 2022.
The Vishay 1000 uF were not available at the time of purchase so I ended up putting Jamicon spare cap I had from a PSU kit. Not the best choice. I will change them next time.
I left a gap between the resistors and the PCB when I soldered them. Those components are likely the get hot so they need space to dissipate heat.
I soldered an insulated terminal to the wires connected to the 33 000 uF capacitors. They have bolts.
I cleaned the PCB with 95% alcohol, a toothbrush and a tissue to remove flux.
The amp +/- rail shows 28.6V and the preamp rail shows +/- 14.6 V. Good !
Feel free to ask if you need more details.