I bought this amplifier in or around 1977. Lately, I used the SA 5300 in the shed/workplace for music, where it was starting to rust. So I decided to try and restore it to its former glory.
After removing the cover, the circuit board proved to be easily accessible on both sides.
As you can see on these two pictures, many capacitors have leaked. So the first step is to remove all electrolytic capacitors. Note that C63 (just above the biggest capacitor) is missing, it is actually on the other side. Also note that C66, which, according to the schematic, should be 220 uF, actually was 330uF.
These are the old capacitors. Two of the smaller blue ones have a resistor connected to it. These resistors are ok and will be put back. I have ordered new 85 degrees capacitors.
I replaced diode D3 (1S2473) with a 1N4148, and diodes D5 through D8 (SIB01-02) with four times a UF 4003. And of course all electrolytic capacitors. And the power light. After I replaced the electrolytic capacitors, the 5 diodes and the 4 fuses, and also the broken power light with a yellow led plus diode and resistor, as you can see bottom left, this was the result:
Notice the capacitor. On the other side, C63 is missing and moved to the underside, the minus connected normally, the plus connected to the minus of C68.
After cleaning all switches and trim-pots, the amplifier was connected to speakers and tapedeck for testing, resulting in a top score. Great sound, no humming or hissing or creaking when turning knobs. So, I deemed replacing transistors as unnecessary. Replacing the cleaned front and spray painted cover resulted in:
