SHP 3 Capacitors and final demo

WARNING Working with electricity is dangerous!!! If you do not understand the basics of electricity, please do not attempt the following project. Failure to use care around electrical devices may result in injury or death. If you choose to attempt this project, you do so at your own risk! Please be careful. This concludes the death disclaimer...

In the this final SHP 3 video, I discuss capacitors and the tone circuits. Then... well, that's it. It's finished. At time of this post, it is playing though a 6 hour playlist of classic rock. The heat sink is just slightly warm to the touch. The bias is steady as a rock, both channels. The sound is distortion free and has the signature “bass-y” sound one would associate with a nice jukebox. I just thought you may like to see a list of items associated with this repair process.

All new electrolytics. Nearly a dozen wires fixed or replaced. New rectifier diodes. All new transistors in the driver board, including the FETs. New mica spacers and replacing the power output transistors. Don't forget the transistor grease. Cleaning the entire unit after a catastrophic failure of a 3000uF filter capacitor. It exploded(in MY FACE...). Chasing a malfunctioning bias adjustment that ate up over 15 hours of total lab time to figure out. (BECAUSE DIODES) The mute trip relay in these are tricky. While trying to troubleshoot another issue, they will “just turn on” and you have no idea where your signal went. All new transistors in the pre-amp board. In order to have 10 precisely matched transistors, I graded over 100. All resistors were checked for values and replaced where needed All non-electrolytic capacitors were checked for capacitance and replaced where needed. Solder joints were touched up and reworked throughout the entire chassis and both circuit boards. Copious amounts of research. More research. Coffee. More research. Solder, clean off flux. Test. Solder, clean off flux. Test. Repeat until old.

This is often what is required(and more) in order to finally look over and see the amplifier idling away, doing it's job correctly. If I did it right, this amplifier won't need touched for a long time. Then a cap change, and proper bias adjustment, and back into service. Of course, now I am committed to finding a way to get “just a little more punch” out of it, without causing any distortion or heat issues. I am thinking along the lines of pre-pre-amp(yes, I did that right). But that is for a later discussion. I like the challenge of finding the problems. If I didn't, I wouldn't do this.

I hope you find this video helpful and entertaining. If so, feel free to hit the “Like” button and subscribe for future videos. As always, thanks for watching. ... https://www.youtube.com/watch?v=zH8kr00SFJs