Bose 901 Series IV ActiVe EQ schematic

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daveyhockett

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Joined 2010
Does anyone have a copy schematic for the above Bose Series IV EQ? I want to recap the one I have and someone else has been in there and changed the main filter caps. I want to make sure they are the correct ones that were installed. The one that they installed are 50V 470uf. Can anyone verify this is correct?

I have searched the forum and Google but I can only find ones for older units.
 
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ctef

Member
Joined 2011
Change them. Bigger is better.
Also, change and all other electrolytic. Use Elna Silmic. Rise them 5mm over PCB.
The first one in the chain is especially sensitive to the noise. If You don't know which it is, try with a naked finger on the top of capacitors, system working, and You'll hear ;)
 
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ctef

Member
Joined 2011
Jsixis said:
what series? I have a stock series II that I need to re cap soon and I could take it apart and look if you need the series 2 version.
I'm for leaving things stock myself. I have read a couple of pages where people have changed things because "they" thought they could improve it ;)
Click to expand...

In Series I&II, is better to exchange the input capacitor and capacitor in the feedback with no electrolytic capacitors. It helps.
To see which they are, use scheme ;)
 
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