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View Full Version : Arcadia 7W PSE 2A3 Power Amplifier Upgrade



sjs
30-10-2015, 18:31
Recently in for some major upgrades was one of the original SJS Arcadia 7W PSE 2A3 amplifiers, originally built back in 1998.

Following the terminal exit of the main power transformer the opportunity was taken to upgrade and almost rebuild it.

The main power transformer was replaced by an external dual mono PSU, containing 6 mains transformers; two for the HT to the 2A3 power valves, two for the HT to the 6072A-5687 input/driver stage, and two for the negative bias supply for the grids of the 2A3s.

https://dl.dropboxusercontent.com/u/30444544/SJS/blogger/IL-psu0.jpg

https://dl.dropboxusercontent.com/u/30444544/SJS/blogger/IL-psu1.jpg

EZ81 rectifiers, choke input and first smoothing cap for the input/driver stage power supply are inside the PSU case

https://dl.dropboxusercontent.com/u/30444544/SJS/blogger/IL-psu2.jpg

Four umbilical cables connect the psu to the audio chassis

https://dl.dropboxusercontent.com/u/30444544/SJS/blogger/IL-psu3.jpg

https://dl.dropboxusercontent.com/u/30444544/SJS/blogger/IL-rear1.jpg

Independent left and right mains switches, with remote switching controlled form the audio chassis

https://dl.dropboxusercontent.com/u/30444544/SJS/blogger/IL-psu4.jpg


Removal of the power transformer from the audio chassis allowed for a pair of larger chokes to be fitted for the 2A3 HT supply, each channel has NOS GZ37 choke input supply and Elna Cerafine HT caps in the HT, and NOS Mullard EZ81 and choke input supply for the bias supply

https://dl.dropboxusercontent.com/u/30444544/SJS/blogger/IL-top1.jpg

Inside there was a major component refresh and upgrade; tantalum resistors, Hovland Musicaps, lots of Black Gates, Jensen 4 pole HT caps, Kemet bias supply caps and silver wiring

https://dl.dropboxusercontent.com/u/30444544/sjs/blogger/IL-inside1.jpg

https://dl.dropboxusercontent.com/u/30444544/SJS/blogger/IL-inside2.jpg

Not looking to shabby for it's age, and now fit and ready to go

https://dl.dropboxusercontent.com/u/30444544/SJS/blogger/IL-top2.jpg

https://dl.dropboxusercontent.com/u/30444544/SJS/blogger/IL-top3.jpg

Ali Tait
30-10-2015, 18:52
Very nice!

sjs
25-02-2018, 15:37
Dropbox changes did for all the images in the original post, so I thought it may be worth updating all the links and putting the photos back in :)

At the end of 2015 one of the original SJS Arcadia 7W PSE 2A3 amplifiers, originally built back in 1998, came in for a major service and upgrade.

Following the terminal exit of the main power transformer the opportunity was taken to upgrade and almost rebuild it.

The main power transformer was replaced by an external dual mono PSU, containing 6 mains transformers; two for the HT to the 2A3 power valves, two for the HT to the 6072A-5687 input/driver stage, and two for the negative bias supply for the grids of the 2A3s.

https://dl.dropboxusercontent.com/s/nlt0l6eeo999nu6/IL-psu0.jpg

https://dl.dropboxusercontent.com/s/o4jaoebgcars2lh/IL-psu1.jpg

EZ81 rectifiers, choke input and first smoothing cap for the input/driver stage power supply are inside the PSU case

https://dl.dropboxusercontent.com/s/mccc0t6ll7urw2j/IL-psu2.jpg

Four umbilical cables connect the psu to the audio chassis

https://dl.dropboxusercontent.com/s/ynp802oh98xycgb/IL-psu3.jpg

https://dl.dropboxusercontent.com/s/9ia4seta2yvy6s4/IL-rear1.jpg

Independent left and right mains switches, with remote switching controlled form the audio chassis

https://dl.dropboxusercontent.com/s/5uhubo37zsr017u/IL-psu4.jpg

Removal of the power transformer from the audio chassis allowed for a pair of larger chokes to be fitted for the 2A3 HT supply, each channel has NOS GZ37 choke input supply and Elna Cerafine HT caps in the HT, and NOS Mullard EZ81 and choke input supply for the bias supply

https://dl.dropboxusercontent.com/s/98q526nmdt8xaox/IL-top1.jpg

Inside there was a major component refresh and upgrade; tantalum resistors, Hovland Musicaps, lots of Black Gates, Jensen 4 pole HT caps, Kemet bias supply caps and silver wiring

https://dl.dropboxusercontent.com/s/8tgj7mpuun4jqsu/IL-inside1.jpg

https://dl.dropboxusercontent.com/s/9qu5kpossgyqawg/IL-inside2.jpg

Not looking to shabby for it's age, and now fit and ready to go

https://dl.dropboxusercontent.com/s/dufr44yt4c3jc81/IL-top2.jpg

https://dl.dropboxusercontent.com/s/wqf141y2jlqxl4g/IL-top3.jpg

chris@panteg
07-04-2018, 13:18
They look stunning, lovely quality amplifier.