PC board for LM317/337 regulator

[Ianmac]

I am building two +/- 21v regulators to replace two of my Cyrus PSX power supplies. The LM317/337 regulators appear adequate for the purpose.
Does any one know if I can purchase "generic" PCB's for these regulators from anywhere.

Ianmac

[sandbasser]

Peter Daniel on this forum sells PS boards that can use LM317/LM337. He's very knowledgable and gives excellent support. I am NOT a shill; but a satisfied repeat customer. You can check his stuff out in the Vendors section - under Audio Sector. Sorry, I don't recognize your flag (Scotland maybe); but Peter is in Canada.

[Ianmac]

Thanks Ray, will investigate.

Scottish flag

IanMac

[AndrewT]

Originally Posted by Ianmac

I am building two +/- 21v regulators to replace two of my Cyrus PSX power supplies. The LM317/337 regulators appear adequate for the purpose.
Does any one know if I can purchase "generic" PCB's for these regulators from anywhere.

Ianmac

which parts of the Cyrus are receiving the regulated power?
The 317/337 cannot pass much current and combined with the high voltage cannot do much power either.

[Ianmac]

Andrew,
In many applications of the PSXR in the Cyrus range it is complete overkill.
There are two versions, the PSX, now superseded, and the PSXR. The psxr is capable of about 4A at +35v,or+21v,or+20v and or +5v. I presume it was designed as a complete supply for the earlier power amps and the PSXR version was also designed to provide lower voltages for other applications like pre amps CD players and DAC's.
The Cyrus unit the psxr is connected to sends a reference voltage to the psxr and it outputs the appropriated voltage. Most applications use only 20/21v at a few hundred milliamps.
The PSXR retails at £500 each with secondhand models on ebay circa £250.
Cyrus will not tell anyone much about their gear I have tried to get a circuit for my 10 yr old APA7 power amps with a polite refusal.
I am reverse engineering and it appears that the PSXR when activated by the cyrus unit supplies the correct voltage to the unit, to the power rail that will be replaced by the PSXR power rail. The PSXR rail is applied to the cathode of the two rect. diodes in the cyrus units psu. The PSXR rail is 2 volts above the unit supply rail so the diodes are reverse biased and the related transformer winding put out of use. The new supply takes over usually feeding 78XX series on board regulators which have to work a little harder with the increased voltage applied to them .
I am having to break into a PSXR /Donor unit interconnect to measure the voltage and current used by the various cyrus unit. This will take time.
A small dedicated PSU can hopefully be used to replace the PSXR an most of its applications. In one CD player the PSXR at £500 feeds only +21v to the motor circuits with the -21v rail driving a resistor.

So I am looking at mostly applications about 250ma to 500ma @ +/- 21 v which I think will be OK with LM317's. I will if necessary use floating pre regulators to minimise heat dissipation in each LM.

I havent used LM317/337's a lot but one drives my Technics TT at 21.5 v, pk 500ma ave 200ma almost daily. Given the Cyrus units have on board regulation I thought the LM performance adequate.
My problems are at the moment how best to switch the LM317 on with the command from the Cyrus unit(+5V) and protect the LM317 when it is connected to the cyrus unit
with the cyrus unit on and the LM317 off. ie 21 volts across the LM317 output with the LM 317 off or at 1.2v with the sense pin grounded


If I am going in the wrong direction any suggestions would be appreciated.


Ianmac

[AndrewT]

Originally Posted by Ianmac

In one CD player the PSXR at £500 feeds only +21v to the motor circuits with the -21v rail driving a resistor.

So I am looking at mostly applications about 250ma to 500ma @ +/- 21 v

try one of ikoflexer shunt regulators for that. Tell everyone how good it is when you have it up and running.

Then try making a dedicated reg for each low current supply that is required.

[peranders]

Originally Posted by sandbasser

Sorry, I don't recognize your flag (Scotland maybe); but Peter is in Canada.

Right click on the flag and choose "view image" if you are using Firefox, then check the image file name.

http://www.diyaudio.com/forums/image...s/Scotland.gif

[peranders]

Originally Posted by Ianmac

I am building two +/- 21v regulators to replace two of my Cyrus PSX power supplies. The LM317/337 regulators appear adequate for the purpose.
Does any one know if I can purchase "generic" PCB's for these regulators from anywhere.

Ianmac

What does the original PSU consist of?

[Ianmac]

The original is a high power toroidial tfr. with twin +and - regulators each using an op amp and power transistors.
It is overkill for most of the applications it is sold for and I want to build a cheaper alternative for use in my own hi fi system.

Ianmac