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Audio Dynamics ca-2000e, idle current adjustment.

Alex22

Alex22

Well-Known Member
I have an old Audio Dynamics ca-2000e, just finished replacing some capacitors as the unit was taking a long time to start-up. I want to adjust the idle current but no manuals are available, this is my first time working on an amplifier and I have no real electronic experience but can use a soldering iron. My question is where do I place multimeter probes to take measurements? and what voltage should it be?

The only other amplifier I have adjusted was an old onkyo that had a service manual and handy points to measure from. That unit needed 7.5mv and I see that many amps are around 20mv. I understand that without a service manual I could be out of luck.

I have taken a couple of pictures, maybe someone could point me to where the probes should be placed.

Any help would be greatly appreciated.

P1020664.JPG P1020665.JPG P1020666.JPG P1020667.JPG P1020669.JPG
 
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Well as the recap is finished, almost 100 of the little blighters, I went ahead and fired it up it came out of protection in a couple of seconds which is perfect considering it was taking between 2 and 10 minutes lately. The 4 10000uf filter capacitors were as expected causing the problem with 2 visibly bloated.

I really like this little amp so it gave it a full recap using nichicons and elnas, this was my first attempt at recapping an amp and am so happy that I didn't screw it up. I didn't worry about changing anything but the electrolytics as this amp despite being made in 1988 was first taken out of its box and powered up 2 years ago, so it is kinda old and new. The capacitors defiantly deteriorated over the years as at least the big ones were dying, all the other caps tested fine but were replaced as I would like this amp to give many more years of service.

It really sounds good to me when compared to my Marantz pm 6004 which isn't a bad amp at all, the Audio Dynamics just drives my old homemade mtm speakers that much better (they are about 4ohms and the ca2000e can drive down to 2ohm speakers I believe).

So the last thing I want to do is adjust the idle current before closing it up again, just don't know where to take the measurements from yet.

I have my eye on a Sansui au-517 that I really don't need with a mind to recapping it just for fun. It will be the last amp I ever buy......................
 
Alex22 said:
So the last thing I want to do is adjust the idle current before closing it up again, just don't know where to take the measurements from yet.
Click to expand...
Welcome to A.K.
W/o a service manual and specs for Bias? You're stuck.
Generally if you haven't changed the output transistors you don't need to set bias. Monitor heat and don't over drive it.
 
Binkman said:
Welcome to A.K.
W/o a service manual and specs for Bias? You're stuck.
Generally if you haven't changed the output transistors you don't need to set bias. Monitor heat and don't over drive it.
Click to expand...

Thanks for your reply,
Yes I think you are right. The output transistors haven't been touched. It is running great and not running hot, I would have liked to check the bias if only to make sure both channels are the same but it is not that important as I only changed the caps and the unit has only run for about 18 months in its entire life, so I expect years of use yet.
 
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