Help find replacement trimpots for a Harman Kardon 330B (B-2) Predriver Board

[puma1824]

I'm in the process of sourcing both caps and other components for my Harman Kardon 330B (B-2) and can't figure out which trimpots I should purchase to replace the old fragile ones on the Predriver Board (see pic). I found an older thread from dlucy which he posted the following which currently aren't available and at the time of the post he wasn't 100% satisfied with them. I tried searching other threads with no luck. Anyone have a recommendation on what I should purchase?

Original list (no longer available):
VR401 Resistor Trimpot 100K - replaced with trimpot 100K 0.5 W 652-3309W-1-104
VR402 Resistor Trimpot 100K - replaced with trimpot 100K 0.5 W 652-3309W-1-104
VR403 Resistor Trimpot 3K - replaced with trimpot 5K 0.5 W 652-3309W-1-502
VR404 Resistor Trimpot 3K - replaced with trimpot 5K 0.5 W 652-3309W-1-502

Possible replacements:
652-3352H-1-104LF
652-3352K-1-502LF

 

[jheu02]

Are the legs all in a straight line or staggered to make a "V"? I would think you'd want to use top adjust. Though I normally use mouser, digikey has a better selection of trimmers from what I can see.

VR401, 402 are for setting DC Offset and some use multiturn trimmers for better precision.
single turn - https://www.digikey.com/en/products/detail/bourns-inc/3362P-1-104LF/1088413
25 turn - https://www.digikey.com/en/products/detail/bourns-inc/PV36W104C01B00/666503

VR403, 404 are for setting bias, and many use single-turn trimmers for this as you want to be able to adjust it rather quickly vs having to turn the set screw MANY times.
single turn - https://www.digikey.com/en/products/detail/bourns-inc/3362U-1-502LF/1088445


You'll need to check the hole spacing and layout, as many times the modern trimmers are much smaller than what's pictured above and MAY require leg extensions. If the board only has two holes, vs 3, you just bend the center leg of the trimmer and solder it to one of the outer legs. It doesn't really make a difference which one, but it will effect whether clockwise turning increases or decreases the resistance. So, if you're used to CW turning to increase bias (and want fully CCW to be zero bias) you'll need to check which leg, when the center pin is attached to it, allows for a decreasing resistance when turning CW.

 

[puma1824]

Are the legs all in a straight line or staggered to make a "V"? I would think you'd want to use top adjust. Though I normally use mouser, digikey has a better selection of trimmers from what I can see.

VR401, 402 are for setting DC Offset and some use multiturn trimmers for better precision.
single turn - https://www.digikey.com/en/products/detail/bourns-inc/3362P-1-104LF/1088413
25 turn - https://www.digikey.com/en/products/detail/bourns-inc/PV36W104C01B00/666503

VR403, 404 are for setting bias, and many use single-turn trimmers for this as you want to be able to adjust it rather quickly vs having to turn the set screw MANY times.
single turn - https://www.digikey.com/en/products/detail/bourns-inc/3362U-1-502LF/1088445


You'll need to check the hole spacing and layout, as many times the modern trimmers are much smaller than what's pictured above and MAY require leg extensions. If the board only has two holes, vs 3, you just bend the center leg of the trimmer and solder it to one of the outer legs. It doesn't really make a difference which one, but it will effect whether clockwise turning increases or decreases the resistance. So, if you're used to CW turning to increase bias (and want fully CCW to be zero bias) you'll need to check which leg, when the center pin is attached to it, allows for a decreasing resistance when turning CW.

Thanks! I'll checkout spacing when I get back home later today.