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Help adjusting 2226b

M

masha

New Member
Hello!

I am brand new to all this and just got my first Marantz, a 2226b. It's working, cleaned the pots and the power switch, it was making noise when turned on but it's gone now. It seems fine but I saw a video on youtube how to check the speaker outputs with a multimeter and when I did, it was not at 0 so I just want to adjust it just to make it perfect, but I don't know where to connect with the multimeter :/

Instructions from the service manual: https://i.imgur.com/XiesrMB.jpg

I did the "7. Power Supply Adjustment", that part was easy, but "6. Power Amplifier Adjustment" is tricky...


https://i.imgur.com/H8a1LZV.jpg (I'm in the right place right? Haha!)

J735+J732 and J736+J732 are easy because they are just one pin but...

Where exactly is R757(+) and R759(-)?

Where exactly is R758(+) and R760(-)?

Also: I should connect to both R757 and R759 to adjust it right? Not one by one? And same with R758 and R760?

Thanks in advance! :)
 
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connect to speaker outputs to set dc offset
r737 r738

i think you are looking at idle current adjustment
 
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Oh, I thought I needed to adjust that too :D Oh well... Might as well do it when I'm at it. To learn...

But still not sure where to connect the multimeter to? To see if the idle current is correctly set to 18.8mV?
 
sorry i am away for a few days and not got the manual and just used my daily quota of downloads from hfe .
 
I got that far but which side of R757(+) should be connected to which side of R759(-), and which side of R758(+) to which side of R760(-)?
https://i.imgur.com/IUNidiW.jpg

I can't find anything that indicates which is + and -?

Edit: Maybe the layout makes it obvious to a professional but like I said, I'm new :D
 
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plus minus doesn't matter . the resistors are in series pairs so connect to the ends that arent connected to each other .
 
Ok I just did that and this is confusing...

I measured one side of R757 to the other side of R759 and it was about 17mV so I turned it up to 18.8mV as it says in the service manual, all good, but then I swapped the multimeter probes to the opposite sides and it showed about 20.5mV?
So I turned it down to 18.8mV and then swapped the probes back again and then it had gone down to 16.5mV? Shouldn't it be the same?

It's the same with the other two. Seems like there's a 2mV difference depending on which sides I measure? Is that normal?
 
I checked again after an hour, it was still the same, about 2mV difference. When I switch sides it says minus on the multimeter so, I put the red probe on the non-minus side on R757 and set it to 18.8mV.

Seems ok, at least this part, the volts. Thanks for the help.

There are some other issues with the unit that I will get back to later.
 
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