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Old 15th April 2012, 06:56 PM   #511
goody75 is offline goody75  United States
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Another question - does anyone know if the 22K resistors in the power supply just after the smoothing capacitors can be changed to 27K or is it a good idea to stick with the 22K? I'm asking because when I placed my order I ordered lots of 27K but zero 22K.
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Old 15th April 2012, 07:52 PM   #512
AndrewT is offline AndrewT  Scotland
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Are the 22k or 27k to discharge the smoothing caps after power off?

Then you don't need them.

Using permanently connected extra resistor loading on the power rails increases the rail ripple needlessly.
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Old 16th April 2012, 12:30 PM   #513
goody75 is offline goody75  United States
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They are after the smoothing caps but before the LED's - could they be current limiters for the LED's? Which now is making me want to ask - what are the LED's for? I'll post a pic from the schematic tonight.
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Old 16th April 2012, 12:53 PM   #514
AndrewT is offline AndrewT  Scotland
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Are the LEDs in series with the resistors?
i.e. must the current that flows through the resistor also flow through the LED and have no alternative route to follow?
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Old 16th April 2012, 09:34 PM   #515
goody75 is offline goody75  United States
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After going through the 22K resistor, the current can either 1) go through the LED's and then to ground or 2) go through another 470 ohm resistor and then to the regulator's.

FWIW, there are two LED's - a green & red - and they are mounted directly to the PCB. The red is on the negative rail and the green is on the positive rail... oohhhhh... I guess the LED's are maybe just indicators letting you know there is power on each rail? Nonetheless, my question about the 22K resistor stands.

Thanks so much for your help, AndrewT.
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Old 17th April 2012, 09:14 AM   #516
AndrewT is offline AndrewT  Scotland
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22k is very high for a voltage dropper to feed regulator and LED?

Can you post the schematic so we can determine the purpose of that 22k and it's expected dissipation?
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Old 17th April 2012, 04:31 PM   #517
goody75 is offline goody75  United States
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Here's the power supply schematic for the Jim's Audio board (not sure if I uploaded the image correctly so I may have to repost).


Click the image to open in full size.
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File Type: jpg JimsGainclonePS.jpg (38.7 KB, 177 views)
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Old 17th April 2012, 07:12 PM   #518
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That schematic is wrong. The 22k resistor cannot be connected that way.
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Old 17th April 2012, 08:44 PM   #519
goody75 is offline goody75  United States
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I will check the board when I get home from work. Thanks, pacificblue.
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Old 18th April 2012, 09:22 AM   #520
AndrewT is offline AndrewT  Scotland
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Customer support by Jim's Audio. No.

What is the world coming to that we continue to buy from this cloner !
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