PAS-3X - "The Last of the Dinosaurs!"

This contains pictures of one LAST PAS-3X preamplifier.
Thumbnail for PAS-3X - Selector switch - front wafer after first cleaning - Here is a look at the front wafer after its first cleaning. Notice that the heavy layer of oxidation and crud are now gone! Another round of cleaning will help clean the wafer itself.
Thumbnail for PAS-3X - Selector switch - front wafer before cleaning - Here's what we started with. This is the front wafer of the PAS-3X Selector Switch. Dirt, oxidation and who-knows WHAT else. Looks like another job for de-oxit!
Thumbnail for PAS-3X - Front Panel Assembled to Chassis - We have assembled the pre-wired Front Panel to the Main Chassis. It's beginning to look like a preamplifier!
Thumbnail for PAS-3X - Initial Mechanical Assembly - Main Chassis - Here is the Main Chassis of the PAS-3X preamplifier with the major components mounted. Next, we'll mate our pre-wired Front Panel and begin wiring them together.
Thumbnail for PAS-3X - Front Panel Shielded Wiring - closeup - Here you can get a good look at one of our "modifications" to the PAS-3X. We're using shielded wiring in order to reduce noise and crosstalk. Notice that the shields are only connected at one end. The shields for the wires that run from the Blend Switch to the Monitor Switch are grounded at the Blend Switch. The shields for the wires that run from the Volume Control to the PC-5 Line Stage circuit board are connected at the Volume Control.
Thumbnail for PAS-3X - Front Panel Shielded Wiring - Monitor Switch - If you look closely at the Monitor Switch, you'll see that the shields are NOT connected to anything at the Monitor Switch itself. They are grounded at the other end ONLY.
Thumbnail for PAS-3X - Back of Front Panel - Pre-wired and ready to mount on the Main Chassis. - Here is our pre-wired Front Panel. Notice the shielded wiring from the Blend Switch and the Volume Control. This is a "modification" of the original Dynaco wiring. Originally, all these wires would be unshielded. In a high impedance circuit like this, additional shielding is a GOOD idea!
Thumbnail for PAS-3X - Pre-wired Selector switch - Here is a PAS-3X Selector Switch pre-wired with shielded Input wiring.
Thumbnail for PAS-3X - Phono Input wiring - Here is the Phono Input of our PAS-3X preamplifier, Notice that we are using twisted wires, rather than totally shielded wiring.
Thumbnail for PAS-3X - pre-wired Chassis - Bottom View - Here is a picture of our PAS-3X preamplifier from underneath. Most of the chassis wiring is now complete.
Thumbnail for PAS-3X - Filament Supply - Here is a close-up of our new PAS-3X filament supply. The silicon diodes won't gradually weaken like the stock "old-school" selenium rectifier.
Thumbnail for PAS-3X - pre-wired Chassis - Top View - Here is our pre-wired PAS-3X preamplifier. All that remains is the Selector Switch installation and wiring of the Inputs and Outputs.
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