KENWOOD Supreme 600 and KA 7300 Recap

vuntruong

Active Member
So, I just got a kenwood KA 7300 and a kenwood supreme 600.

now i need to Clean it up, and get it up and going. i want to replace some caps, but i'm not sure which cap to replace. I have downloaded the service manuel for both amps, and right now, i'm about to order some caps.

the KA 7300 is working properly. Unfortunately, the supreme 600 is making humming noises, I'm not sure whats going on with the 600 yet. I will clean it this weeken after the superbowl and see what wrong with the amp. any suggestions? how and where should i start to restore these amps?

my journey to restore kenwood KA 7300 and supreme 600 is about to start. any suggestions? i want to setup my system like so. Computer-->PS audio DlIII-->kenwood supreme 600, KA 7300, pioneer spec4----> home made scanspeak speaker kit.
 
Replace all the electrolytic caps. With equipment this old, you can't sort which ones are bad or not. You might to leave the power supply untouched as they are more expensive but I'd change them as well.

If you have the schematics, some coupling capacitors might be replaced by high-grade film capacitors as well.

You will have to measure BIAS and DC OFFSET as well, you might also mwant to change the trimpots for newer ones too.
 
Its best to change out all the old caps in these amps since their 30 years old. Especially the power supply caps and the big coke can caps too.

Also, change the old trimpots as was metioned in the earlier post because the ones in the KA-7300 are very touchy and will usually go out of spec.
 
supreme 600 preamp section doesnt seem to be working properly. Power amp is fine, just a couple of bad resistors. At least the right channel is fine. I decided to use only the power amp section. Looking at the schematic, I dont see any coupling Caps that i could change. I've just recap the Power supply section. I'm not sure i need to change the four electolytic caps in the power amp. Oh yeah, anyone need the preamp section for spare parts?
 
I think u are right EW. But I had some time on my hand, so i picked up a 600 and 7300. I just wanted to learn more about these amp, and see how they sounds vs pioneer spec4. well, I am starting to learn a lot.
 
Yeah Jkoyt, U are right, but I was able to buy the supreme 600 (not working condition) for really cheap, so I couldn't pass up that deal. I would get it service by a pro, but I don't really know anyone around here that service old amp. To ship it to someone would cost about half the amount i paid for the amp. A kid gotta start somewhere to learn about these things. Anywho, It seems like someone worked on that amp before, and seriously mess it up. He/She super glued the volume knobs together, mess up the volume attenuators, and right now, one of the channel is not working at all ( got burned). So i've taken the amp apart, and is currently trying to fix left channel. I've replace all the caps on the regulated power supply board, and it seems to be working fine now. On the power amp board, I've replaced all the Caps, some of the resistors, replaced 2sd381, 2sb536 with NTE291, NTE292. replaced sanken 2SA747A, 2SC1116A with NTE281, NTE284. So far, the left channel is making music, but is really weak, distorted, and sometime it is cutting off. I think the voltage/current is not getting into the amp properly. I gotta check the amp board again. I haven't check the current bias offset yet, so I am not sure if this is the problem.
 
Sounds like the very best thing is to send it to a GOOD tech like EchoWars, or sell it for parts or repair.

(BTW, AK rules prohibit soliciting items for sale except in the classified ad section.)
 
So EchoWars service these amps? Let's see where he is located. Right now, the amp is in pretty bad shape. It is a mess! :( . Not my fault though.
 
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