The Phonoclone and VSPS PCB Help Desk

[rjm]

Originally Posted by tkwou

Would the LME49713 current feedback opamp work in the first stage?

It might, yes. Though it needs a DIP-SOIC adapter and possibly some ceramic bypass caps.

[DARIO1997]

Hi Rjm and other manufacturers of Phonoclone 3,

i have a problem with my Phonoclone 3, it picks up radio signals.

The boards have been purchased by RJM, already full of components, so I just put the boards in the chassis and connected to the RCA, while the power supply is the same as my VSPS.

Can you help to reduce radio interference?

Regards

[rjm]

330 pF capacitor between the inverting and noninverting pins of the input op-amp should reduce the interference. You can solder the capacitor to the underside of the board, to pin 2 and 3 of IC1.

Also be sure to use shielded cable for the phono interconnects.

The OPA27 op amp is susceptible to RF pickup, and careful shielding will be needed when the phonoclone is used in places where RF interference is especially strong.

[DARIO1997]

Hi Rjm,
i have change the phono cable and the RF interference are almost missing.
If solder the capacitor to the underside of the board, to pin 2 and 3 of IC1, the sound changes?
Regards

[rjm]

The input capacitor should have no influence on the sound.

[WindChill]

I'm starting to case up the power supply and VSPS 300i boards and I had a few questions.

In the power supply, I'd rather not have to drill through the bottom of the enclosure for a bolt to mount the transformer. How are you all mounting the transformer?

The power supply just has a transformer, fuse, switch, and rectifiers. I noticed in a search that the rectifiers can be mounted directly to the case since the package has a through hole. I guess I expected to mount the rectifiers and fuse holder on a small board though. If the rectifiers are attached to the case, is there a good way to do that, again, without drilling through the box?

I think the same question comes up with attaching the boards too. I have the standoffs mentioned in the construction thread and I was looking for ways to mount them to the box without putting holes in the box.

I'd appreciate any ideas, thanks all.

[rjm]

Here's an nice example of a typical build. Yes, rectifiers and toroid are bolted to the chassis; that's the normal way to do it. In principle diodes and transformer could be bolted to a board, and the board slid into the chassis if your chassis has rails to allow this..

[WindChill]

Very good, I can do that. Do you do the same thing with the VSPS boards and attach them with screws through the case to the standoffs?

[WindChill]

Originally Posted by rjm

Here's an nice example of a typical build. Yes, rectifiers and toroid are bolted to the chassis; that's the normal way to do it. In principle diodes and transformer could be bolted to a board, and the board slid into the chassis if your chassis has rails to allow this..

One other question -- is that a special T connector for the common outputs from the rectifiers? If so, can you point me to where I could get those?

[rjm]

The boards are normally secured to the chassis with standoffs, 5-8 mm in length, and M3 screws. I dug another photo out of my PC that show this.

The photo is not a power supply I built, but looking at the photo the "T" connection is almost certainly soldered wires covered with yellow electrical tape.