No!!

[thearnicasync]

Hey.

I finished everything, tested +/- 14v in and out of the opamp headers, adjusted it up to 18v (avedis). I've got LED on the card. I'm just not getting ANY output. It's so weird.

I guess I'm just wondering if there's any really definitive information about how this circuit works, because I'd really love to troubleshoot it myself. Also, If you have any ideas about what might be wrong, I'm you're best friend.

Here's the current situation:

No obvious soldering problems.
diodes are correctly placed
output tranny leads are correctly placed.
18-20v at pins (3,5) of u1.
molex connector passing 48v for phantom, and 27.4v for power...

I'm thinking this has to be an output issue...like between the opamp and the output connector? I'm ruling out things like resistors and caps, becuase I'm thinking they'd at least pass some signal. Bad signal, but signal nonetheless.

No!!!

kelly

[thearnicasync]

I'm using the avedis opamp. I've never used an op amp in a project (except paia, years ago), and I assume you just clip the leads and seat it in the headers. Maybe I'm missing something...?

I did short pins 3 and 4 for a second when testing...a tiny spark between the pins. Voltages didn't change...maybe I fried it?

Bah,

kelly

[tele_player]

The schematic IS the definiteive information on how it works, and it's a really simple device. The signal flow is quite obvious on the schematic.

Troubleshooting it is simple with a signal generator and a scope. As Tim pointed out in another thread, you can create a simple probe to test for the presence of signal.

Did you install the Jensen isolators? If not, did you jumper across their location on the board?

[thearnicasync]

I'm at work now...I'll check my my jumpers when I get home.

Thanks...!

kelly

ps: Hey Tele...do you mean like wires across L1 and L2? That could definitely be my problem...I didn't think there were any jumpers outside of the actual jumpers that were designated on the PCB...

[tele_player]

Yes, wires - top of page 3 in the assembly instructions. It's pretty important

[thearnicasync]

Hey Tele or Tim or anyone who has done the jumpers for L1 and L2:

Sorry I'm dense! Where do you solder these!? I see pads for L1 and L2, but there are three additional pads (two diagonal) on L1. Here, I'll cyber draw it and number it.

Top View. And if you can, ignore the solid lines...there just there to preserve the formatting. The letter 'o' represents each pad, and they're numbered.

L2(1)_________(2)___L3(3)_____(4)______(5)
o------------------o_______o---------o----------o
______________________________(6) o
_______________________________(7) o

Can anyone tell me which numbers to connect?



Wow...I hope this is all it needs!

kelly

[tele_player]

Look at the picture on the instructions page - you'll see exactly how L1 and L2 get installed. But instead of installing L1 and and L2, use two pieces of wire.

The little holes (situated diagonally) in L1 aren't pads, they're feed-throughs. Ignore them.

[thearnicasync]

Thanks Tele...that got my signal through.

Man, I love the sound of the a12...just tested it with an acoustic guitar.

Something weird is happening though...

When I switch the phantom on with an sm58, it sounds normal, with big bass and proximity effect. When I shut the phantom off, it sounds like AM radio.

Any ideas? Thanks and so sorry to bother...!

kelly

[tpryan]

Do you have J3 and J4 installed correctly? Are you sure R33 and R34 are the right values? Have you installed J1 and J2? You don't need them with the CineMag input transformer. Let us know what you find.

[thearnicasync]

I'm stuck at work, so I can't look immdiately, but I do know:

1. j1 and j2 are not installed, and I'm using the cinemag.
2. I tested resistor tolerances for each resistor as I stuffed the board, so I'm pretty sure they're right.
3. I'll be able to check j3/j4 when I get home.

Man, it sure sounds good!

kelly