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Harman/Kardon A500 Tube Amp

Thanks Gadget, as usual, your help is invaluable. Will try it in the following days as I have a lot of spare time in the following due to our new way of life ;).

Just lazy to disconnect the amp, speakers, open the cover and test with DMM. Anyway, when I'll be there, I'll probably replace the the tone and volume caps to eliminate those variables. There are also a lot of switches on this beast and I will deoxit all of them for good measure. Anecdote about it: listening to a vinyl yesterday (Yessongs) and wondering why right channel was sounding weird and appearing lower in volume: my girlfriend or son have flipped the phase switch by mistake probably looking for the power switch. GF hate my old tube gear: "Too much buttons and switches, some labeled "volume", some "loudness""...
 
yeah the phase switch makes things sound really strange. Never been a fan of that one, it tends to cause a lot of dumb problems when the contacts get funny.

I'd rather have a lot of controls than a menu with all the options buried 16 levels down.
 
Solved (I think): even in this pandemic/chaotic period, I'm lazy but finally came to the conclusion that it was probably a really dirty pot.

Tired of the behavior of crackling/jumping volume, I exercised the pot back and forth (20-25 times) until no noise was heard. Looks ok now. In fact, before this, just pulling a bit on the shaft and it was misbehaving...
 
Gman1 said:
Thank you!! I plan on running my electrovoice ev sixs with it and also bozak concert grands. Any input would be appreciated!
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Wow...im waiting for my a500 to come out of the shop for my ev sixes too. And my new set of concert grand are in covid quarentine!! Very coincidendal. Ill post more when i have it up and running.
 
Gman1 said:
Wow...im waiting for my a500 to come out of the shop for my ev sixes too. And my new set of concert grand are in covid quarentine!! Very coincidendal. Ill post more when i have it up and running.
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Looking forward to that Gman1! Your N-106 is recapped and ready!

Smiley
 
buickguy62 said:
I've restored a number of these with input from Jim McShane. I replace at a minimum all the electrolytic and coupling caps, the balance pots and the diodes, and liberal use of De-Oxit. I have an Excel spreadsheet that lists the components and sources I use --it's a good place to start--you might have your own preference on component selection. PM me for the spreadsheet if interested, I also have the schematic if you need one. One trick I've found is to use two of the dual 50/50 ufd. 500V JJ can caps from tubesandmore (to replace C29 A&B, and C30 A&B). They are under $10 each (plus the clamps), they fit in the existing holes and allow plenty of room underneath for the additional caps-see pics--that area gets crowded if you put all of the replacement caps under the chassis. See pics.
Tom
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Buickguy62- I am glad to see you are still here at AK. I would love to have you share your re-build files with me. Mine is the A50K that I've have one here for 5-10 years. It sounds great, I use it very sparingly just to keep the electrons fresh! However I want a project and this is a worthy candidate and it simply just deserves it. It has the original tubes but I did steal a couple Telefunkens that I use in my Luxman tube amp.

Looking forward to your help-thank you.
 
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