Seventh Circle Audio

edwin · Joined: 07 Feb 2007 Posts: 7 Location: Boulder, CO

How do I tell which version of J99 I have and what are the differences?

Thanks,
Edwin

tpryan · Site Admin Joined: 04 Dec 2003 Posts: 1737

Version numbers are screened on the board, but you may have to look under the output transformer. The previous versions of the documents are still on the server. You can get to them by changing "J99R36" to "J99R34" or "J99R33" in the URLs.

edwin · Joined: 07 Feb 2007 Posts: 7 Location: Boulder, CO

Thanks! The pres are now in my chassis, so I don't think I'll rip them out just to check on this. I'll download the old docs and see which ones look most like what I remember seeing.

I take it that there isn't too much of a functional difference.

Happy holidays!
Edwin

tpryan · Site Admin Joined: 04 Dec 2003 Posts: 1737

The most recent revision added slow-rise phantom power switching and brought the maximum gain and input impedance in line with the A12 and N72. Jumpered for 1200 ohm input impedance, maximum gain is now 70dB instead of 78dB.

eman kayker · Joined: 11 Mar 2008 Posts: 11

Instructions 34 don't correspond to my 3.4 pcb
Hi
I build a J99 doing cross examination and few deductions... and I was wrong. I got a smokey R30 on my board that says rev 3.4
I tried to use the different address (http://www.seventhcircleaudio.com/J99/J99R34/docs/j99_asmbly.pdf) but it is not the same, the board on this pdf is a dark green, there a single large cap in place of my c7 and c23 under the 2 big rows of resistors close to the switches and pots, I have on my board the 2 jumpers J6 and J8 with ADJ that don't appear on the 34 pdf, etc...
Could you give me the correct instructions for this one? and if you already know what could be wrong with that R30, that'll help!
Thanks
e

tpryan · Site Admin Joined: 04 Dec 2003 Posts: 1737

Here's the schematic: http://www.seventhcircleaudio.com/J99/J99R34/docs/j99_sch.pdf

Here's the BOM: http://www.seventhcircleaudio.com/J99/J99R34/docs/j99_bom.pdf

If you can't make sense of it from those, I don't know what to tell you. R30 should be 1K24, in series with 1K pot R28. Even with the regulator adjusted for +24v, there's no way to smoke it, assuming everything else is correct.

eman kayker · Joined: 11 Mar 2008 Posts: 11

Hi Tim
Yes I do have the schematic and the BOM on the printed papers coming with the kits but the assembly instructions are not corresponding with my board anymore. None of the ones that are online. This would help me to build my second J99 and troubleshoot this one.
Why do I have a different 3.4 version?
Thanks

Archmart · Joined: 02 Apr 2007 Posts: 52 Location: EARS Chicago

Hey Hey!

Two and a half years since I last worked on my 5th of 8 kits (2 of each at the time). I'm about to resume and finish up one more J99 and two N72s.

The J99 is Rev 3.3. I wonder if there's an upgrade path I should take before I put the work in, bearing in mind that I want this one to match the one I already built as a stereo pair.

Please advise.

Thanks,
Archmart