Wednesday, 30 May 2018

Upcyling / Recycling an Old Stereo Amplifier - Chapter 2

Upcyling / Recycling an Old Stereo Amplifier - Chapter 2 - Intro


In chapter 1 we saw me taking apart a 20 year old system I knew nothing about and trying to retrofit new components (which I knew nothing about), with some exciting but disastrous results.

Summary: Unless you spend some hours looking at you old and new parts and really understanding what things do then you will likely not succeed.

Cheap class D amplifier boards are quite reliable for building active portable speakers, where a casing is wood or plastic, and the amplifier is always attached to the speaker. I have done this 3 or 4 times with no problems. But building a amplifier, has proven far more vexing.

Upcyling / Recycling an Old Stereo Amplifier - Reusing an Old Power Supply

Even the title of this section underlines my ignorance. I measured output voltages from the old transformer only, and as such there were many unknowns. Although a power supply may supply 12V or 24V what current can it support?

Upcyling / Recycling an Old Stereo Amplifier - Speaker Terminals


Although there were eight wires leading to my 8 speaker terminals, some were bridged. This created a short circuit when I used them with my modern Class D amplifier which cannot (i liveable) have shared grounds. 

Upcyling / Recycling an Old Stereo Amplifier - Un-Painted Metal Cased

For a beginner a plastic or perhaps wooden case is more forgiving than a metal case. A dropped wire, or a miss-placed screw can create all sorts of problems. 

Upcyling / Recycling an Old Stereo Amplifier - Conclusion

If you really understand electronics then it may be possible to reuse some of the old components out of an old amplifier. The less you understand the more you should disassemble. 

For example a capacitor pulled from a boards will likley behave predictably as per specs printed on side. But. . . .

A module such as speaker terminals module with PCB may hide surprises that you can so without! 

So in ultimate summary reusing base components is less likely to get you in to trouble than trying to fit new modules in with older modules, they may not "play" nicely. 

Lastly I had some help with this project from folks over at DIY Audio Forum.  So thanks for that guys. Link to post below:


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