[Hairball Audio]

Thanks!

1. No-touchey Confirmed. used 512 DOA, distortion gone
2. I have these correct.
3. I've re-hit most the joints.
4. Hmm.

I'll re-heat remaining pads. then likely post a pic if I'm still having issues.  I have a few different ic's, just hoping not to have to undo a chip as I don't have desoldering gun.

BTW, This kit was missing 200k resistors (had 100ks) Also the ceramic 100pf paired with R503 was the wrong value. I had these in my cache.

Stepped Gain is the way to go!
Cheers

Which was the wrong value, the cap?  Those definitely should have been correct.  It's the only ceramic disc cap we have.

Sorry about the 200K issue we knew about that one, thought we caught all of them.

So it works fine with the BA512?  Or are there still issues?

Mike

[midnitestudios]

Just finish building my copper preamp but i am not getting any sound. Both pots are cranked but still no sound. Any ideas?

[Hairball Audio]

That could be many things.

-missing a link/short
-backwards polar cap is tripping the fuses on the PCB.
-missing component.
-BA512 not seated right.
-transformer not wired correctly.

Post a couple pics of the PCB?

Mike

[midnitestudios]

Pic1

[midnitestudios]

Pic2

[midnitestudios]

Pic3

[Hairball Audio]

There is no opamp.  Did you get a BA512 opamp in your kit?

Like:

http://www.hairballaudio.com/shop/product_info.php?cPath=37&products_id=140

[Hairball Audio]

C503 should not be shorted.  Cut that short.

[midnitestudios]

Yes, i do have the op amp. I took it off so i can get a better picture of the components.

[Hairball Audio]

You have shorts where you should have omits.

Read the build guide about shorts and omits:
http://www.hairballaudio.com/blog/d_assembly/elements-mic-pre-series/elements-populating-the-pcb/

Near the start.  Omit means leave it empty.  You need to cut out those shorts on C502, C503, C504.  I think that's it.  Look for other omits in the BOM.

[Hairball Audio]

R500 is the only position you short in the copper I believe.

[Hairball Audio]

Basically you're shorting your signal to ground (killing it) before it even hits the op-amp.

Mike

[midnitestudios]

What a rookie mistake. Thanks so much for your help!!!!!

[midnitestudios]

I am still not getting any sound. I removed the shorts fromc502-c504.

[Hairball Audio]

No signal leads me to believe the fuses are getting tripped by something.  Things that could trip the fuses:

- C104/105 are reversed in polarity (these seem right)
- Q600/601 are in backwards or are swapped.  Looking at your photo, they are in the right direction but make sure you have the PNP in the PNP spot and the NPN in the NPN spot.
- resistor shorts

No tripping issues causing no signal would be:
- transformers wired wrong.
- maybe an issue with the DI switching (does the DI pass signal?)

I need to sleep.  Go through it carefully and I'll check this thread in the morning.  Try the DI see if the relay circuit is weird.

R504 is 20KΩ?

Good luck!

Mike

[Indecline]

2. Output transistors Q600/601 are reversed or installed backwards.

That will cause the fuses to trip.. Found that out the hard way when I took out the fuse to troubleshoot! 

[Hairball Audio]

2. Output transistors Q600/601 are reversed or installed backwards.

That will cause the fuses to trip.. Found that out the hard way when I took out the fuse to troubleshoot! 

Ya, you're reverse biasing the transistors which will pull a ton of current.  More than the 100mA fuse limit and they will trip.  They are reset when you power cycle your rack.

One thing you can do to check is get your DMM then find a GND point on the PCB you can clip to.  One of the sides of R303 or R301 for example.   To determine which side is grounded, look for the side that has continuity to the GND pin.  Then clip you back lead to that and clip your other lead to the leg of a fuse that is furthest from the edge card. 

Now carefully slide it into the rack (you'll need an empty space to two to the right to let the DMM leads come out) and power your rack.  Test each leg furthest from the edgecard.  You should see a 16VDC, -16VDC, and 48VDC at the legs.  If one or more is 0VDC that fuse is tripping.

Mike

[midnitestudios]

No signal leads me to believe the fuses are getting tripped by something.  Things that could trip the fuses:

- C104/105 are reversed in polarity (these seem right)
- Q600/601 are in backwards or are swapped.  Looking at your photo, they are in the right direction but make sure you have the PNP in the PNP spot and the NPN in the NPN spot.
- resistor shorts

No tripping issues causing no signal would be:
- transformers wired wrong.
- maybe an issue with the DI switching (does the DI pass signal?)

I need to sleep.  Go through it carefully and I'll check this thread in the morning.  Try the DI see if the relay circuit is weird.

R504 is 20KΩ?

Good luck!

Mike

Everything seems to be right and no, i am not getting any sound when using the DI

[Hairball Audio]

No signal leads me to believe the fuses are getting tripped by something.  Things that could trip the fuses:

- C104/105 are reversed in polarity (these seem right)
- Q600/601 are in backwards or are swapped.  Looking at your photo, they are in the right direction but make sure you have the PNP in the PNP spot and the NPN in the NPN spot.
- resistor shorts

No tripping issues causing no signal would be:
- transformers wired wrong.
- maybe an issue with the DI switching (does the DI pass signal?)

I need to sleep.  Go through it carefully and I'll check this thread in the morning.  Try the DI see if the relay circuit is weird.

R504 is 20KΩ?

Good luck!

Mike

Everything seems to be right and no, i am not getting any sound when using the DI

See if you can check your V rails at the fuses as described in the last post.

Mike

[Hairball Audio]

See if you can determine if you're rails are ok.   That's the next thing we need to know.  That's  definitely help track down the issue.

Mike