Transformer Screen & Signal Grounding Issues - Page 17 - diyAudio
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Old 17th October 2010, 10:11 AM   #161
AndrewT is offline AndrewT  Scotland
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Quote:
Originally Posted by mymindinside View Post
how do i measure the dc bias across the output cap?
set your DMM to 200Vdc.
Carefully attach the measuring probes to the two terminals of the capacitor.

C4 & C6 are simply part of a big RC filter between the rectifier and the amplifier.
This filter will not stop the output capacitor charging nor discharging.
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Old 18th October 2010, 02:57 PM   #162
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Originally Posted by AndrewT View Post
You either accept that charging/discharging current passing through your speaker or you fit a speaker isolation switch or relay to provide an alternative current path. You must have a current path. There is no charging/discharging if you leave output open ended during the switching.
Would resistors R13, R15, and R15 (all 47R 3W) provide the current path for charging/discharging if there were no speakers connected? these resistors are connected across the output; i.e. from the negative leg of the output capacitor to ground.

cheers,
mymindinside
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Old 19th October 2010, 12:00 AM   #163
AndrewT is offline AndrewT  Scotland
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Originally Posted by mymindinside View Post
Would resistors R13, R15, and R15 (all 47R 3W) provide the current path for charging/discharging if there were no speakers connected?
I was not paying attention.
These three resistors effectively give 15r in parallel to the speaker load.
At 9W rating they are going to get more than a bit warm.
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