Kenwood KA-9100 DC Stereo Integrated Amplifier Restored and Upgraded

1) Replacing every single Electrolytic Capacitor in the entire unit. The "lytic" part refers to the fluid that is responsible for the function of this component that will at some point evaporate. The mfg. data indicates a 10-20 year useful lifespan for electrolytic caps, these amps are 47 years old. Be aware, this does not change even if the amp is "new".and unused. Many test way out of spec when I test them. The amp "works", but not up to the original design. When these caps fail, they can wipe out entire circuits in including the outputs which are hard to find and very expensive. The higher cost of this amp is justified by the increased reliability and future lifespan.There are literally dozens of them in an amp like this. I have replaced all caps in the audio path with Nichicon "fine Gold" series. High grade Nichicon were used for the power supply. These are far superior to what was even possible in 1977.. The main filter caps have been upgraded to "Audio Grade" quality. I actually show my work and have feedback to support alll claims I make.The low end response of this amp is amazing! this is an actual upgrade and separates it from most others listed.

2) The protection relay has been replaced with a high quality Omron. This is absolutely necessary because unless the amp existed in a "vacuum" for 47 years, the contacts have tarnished. 

3) The transistor that operates this relay has also been replaced. The relay in this amp engages in approx. 3 seconds. I have had many of these that took as long as 30 seconds, some longer. that is because this transistor is "always on" and is slowly failing. 

4) Due to the amount of heat generated by this type of amp, there is considerable thermal stress placed on many key connections. The Phono amp has transistors that literally "desolder" themselves over time and must be reflowed with fresh solder. The power supply board has header pins that develop "cold solder joints" as well.

5) Potentiometers that are "open air design" (which this amp employs) are self cleaning by design. They must be periodically maintained or they will become "scratchy / intermittent". The only way to clean these properly requires the type of access you see in the pictures. They still can require "several turnings or repeated pushing" to provide trouble free operation. All switches and pots have been thoroughly cleaned / lubricated and operate smoothly without any "clicks or pops". 

6) The DC offset measured at the speaker terminals hovers near 0 +/- .3 mv

7) The meters have been calibrated.

8) I have had many of these that smell "funky" and can stink up an entire room after being "driven hard". The pictures show that I literally completely disassemble down to the last screw. Everything gets treated with 90% Isopropol Alcohol and the amp has been literally "disinfected". It smells like a new piece of electronics that has just been unwrapped. 

9) I installed LED lighting for the meters, pilot, and added an updated vibe by including internal accent lighting!

10) The darlington transistor packs have been remounted with new thermal grease.

11) Upgraded Speaker Terminals for Banana Plugs or Wire

This amp was tested for an entire month driving a set of JBL-L100's along with a set of Vandersteen Model II representing a 4 ohm load. It is set to be fully functional at or above the original specs for another 47 years!! The other examples offered will be hard pressed to survive much longer without failure of some kind, or reduced performance despite "looking good". Buy this while you can, you may never seen another like it!

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