Quad 405 Amplifier Restoration & Upgrade Using MJ15022 As Final Transistors (Part 2 Final)

Continuing from the part 1, now this amplifier will be assembly with the boards and rewiring the power supply cables. Let's take a look on the progress.

As you can see, the capacitor on the board has replaced with Elna Silmic, then the MJ15022 will also install in this board.

Apply the thermal paste when attach to the heatsink, this high quality paste will keep stick on the heat-sink and not dry by times.

The finished board with some components been replaced to the higher quality parts.

I still adding the current limit board on the speaker terminals. I believe this board can be remove completely without any effect. But for now, let it be there.

The next steps is measure the size of the board for the new power supply components.

I make a bigger hole and marking the polarity. This would be a complicated job.

Adding 100nF old stock Phillips MKT for snubber capacitors. This will lead for extra smoothing on ripple cause by rectifier.

The connection between board and transformer is now begin. Of course with the new wiring cables.

The configuration is dual mono, means it will require more cables. It is quite messy right now. And for sure, this upgrade is not for the beginner.

Now the magic happened, when the board flip to it's place, tadaa... the messy cables are now disappears.

Very tidy isn't it? You don't see much cables around now.

I am using direct connection with solder instead of the sockets. This is high voltage amp. Each channel will accept 110 volt DC from the power supply. Loose contact a little bit will lead to produce heat on the connector itself. Not a good sign for efficiency and performance.

When the power cables are completely connected to the board, then it is time for the input connection using coaxial cable. Note that this high quality interconnect cable is from Canare and actually very suitable for this kind application due to it's internal shielding and bigger cable diameter.

The components upgrade is all in place.

The rest is assembly the remaining body parts, such as side panel and lower panel of this amp.

Right now this restoration process is completely done.

This amp is now running for an initial test for next several hours. It sound promising on this test. Next time I will try to have an audition with this amplifier. I will check the sound performance and improvement of this little mighty amplifier after this upgrade.

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