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K&K Maxxed-Out Help

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Posted on January 10, 2023 at 07:10:28
WntrMute2
Audiophile

Posts: 782
Location: Detroit
Joined: September 16, 2002


I tried posting this over on the K&K forum but that forum has gone mostly dark.
I am trying to troubleshoot my K&K single-ended phono stage. I am getting varying voltages at the plates of the two dual triodes.
In place of the 100Ω resistor at R103/R203 there is this small circuit board seemingly poorly soldered in the resistors place. Would anyone know anything about this? What function it performs? How would I test for proper functioning?
This just one of many points I am trying to work through.
Thanks for any light shed upon this.




 

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RE: K&K Maxxed-Out Help, posted on January 10, 2023 at 08:05:52
tubejack
Audiophile

Posts: 211
Location: New Braunfels, TX
Joined: November 26, 2003
 There were several revisions (upgrades) over the years for the Maxxed Out Phono Stage. The board shown is probably a CCS plate load replacement for the original plate load resistor. Do you have the schematic for this version?

 

RE: K&K Maxxed-Out Help, posted on January 10, 2023 at 08:29:46
WntrMute2
Audiophile

Posts: 782
Location: Detroit
Joined: September 16, 2002









I believe there already is a plate load CCS. Picture attached. They are replacing R103/203. I'm not sure in any way that they are the problem. They are just an unknown.
The schematic and build guide do not mention that resistor replacement circuit board.

 

RE: K&K Maxxed-Out Help - This describes it, posted on January 10, 2023 at 08:52:29
Chip647
Audiophile

Posts: 2652
Location: The South
Joined: December 24, 2012
 Part of the cathode sink replacing R103/203

 

RE: K&K Maxxed-Out Help - This describes it, posted on January 10, 2023 at 12:57:27
tubejack
Audiophile

Posts: 211
Location: New Braunfels, TX
Joined: November 26, 2003



You are correct. The Plate CCS was an early original upgrade. As the schematic shows a JFET input, the next upgrade was a MOSFET front end with the small SMD current source to bias the MOSFET. There was also a small power transformer board mounted next to the original choke to provide the negative voltage. The original Power Supply was redesigned with the needed output winding and the extra transformer was deleted in subsequent revisions. The pic was my Rev2 board (circa 2008) with all the subsequent upgrades. It was recently sold, so I did not have the documentation to refer to. Thanks for posting the link.

 

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