low noise Pre-Amp / DAC power supply MJE15034 TL072 Regulator based on STUDER 900

[niamex]

That's right for rev.1.2 but not 1.1

 

[jimk04]

I managed to short the output of one of the rails of my dual Studer 900. Now it isn't playing ball. What might be the failure mode of a short on the output of one of these Chinese studer 900s? . thanks 👍🏻

 

[mizohalen]

It should be the bjt transistor

 

[jimk04]

Which one is that...the one on the heatsink?

 

[igor_susman]

Hello everyone.
Aliexpress v1.2 board is taking ~6.5s to reach 21V on the output with 23.6V on the input bulk cap. This is not reasonable for my use case.

Thanks to this post (other schematics shared by the members aren't accurate, for the v1.2 that is) I figured it's the C4 and C5 that define the run-up time. Replacing original 47uf with 1uf caps shortens the run-up time to ~0.25s.
Cheers

 

[ronnieponsones]

I have recently purchased a version with a new board layout which has a larger heatsink and a variable resistor to set the main voltage. It also has quite a bit of room for upgrading the caps which I have done (as well as fitting a proper earth connection to the chassis). Here is the original version before modification.

View attachment 1173290

Here is the modified version.

View attachment 1173291

 

[niamex]

Replacing original 47uf with 1uf caps shortens the run-up time to ~0.25s.
Cheer

Thanks Igor, will try it

 

[niamex]

Hi Ronnie, will you please share in more details the modes you have applied in order to copy them, thanks

 

[niamex]

 

[niamex]

Have replaced the opamp with a LME49720 Dual High Performance, high fidelity and paralelled the existing caps with 220 nano NOS polystirene