Creating a new audio amplifier part 6.

It has been quite a while since I last posted. I have made some progress, but I hadn’t realized how much work needed to be done. The main problems have been making a mount for the heatsinks, – made worse because I wanted them to be insulated from the chassis – and fitting things into the existing case.Well, in a lot of cases working out how to do this.  I have partially completed the P19 and P88 boards and have a rough idea of how the power supply will be implemented.

Rough power supply layout and board mounting

This is the power supply board showing a vague idea of the locations of some components.  I intend to also mount lm317 lm337 regulators on this board using pieces cut from a CPU heatsink to cool these and the diode bridge. The large terminal block is from the airconditioning equipment that the amplifier heatsinks came from.


Aligning the heatsinks

I aligned the heatsinks by clamping as shown with a piece of angle drilled at the distance of the amplifier chips (just fitted into the board not soldered) to make sure the module will fit.  I intend to solder the amplified modules after they are mounted to the heatsinks.

Amplifier positioning



I clipped the angle to the amplifier modules and then marked the holes prior to drilling. The angle is used to make sure the main heatsinks must stay at the correct distance apart while make the mountings and then when the heatsinks are mounted. After comparing this image with the one from the Elliot Sound site I can see that my heatsinks are easily large enough.



Heatsinks positioned in the case

At right is shown the heatsinks in their final location. Two cross beams will support them and these will be insulated from the case.



Partially contructed pre-amp


The pre amp board. I did have some problems soldering these boards as they are so small and my eyes have degraded somewhat since the last time I did any soldering. Even with magnifying glasses sometimes I was guessing where to hold the iron.  Luckily I have some lead solder left (I am still using only the second roll I ever bought).


I have progressed a little further since these photos were taken. In particular I think I have nearly all the remaining components and have finished the mounts for the heatsinks. I did decide to use plugs for all connections to both boards, this will mean they can be mounted while I layout the wiring since everything will just plug in. Easier for maintenance also. This weekend the rest of the family are going to visit inlaws so I am hoping to get a fair bit done.

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