Feeler: an "Eee-Zzz" christmas present...ez1073 and ez1073-500

Farnell - 1209855

http://uk.farnell.com/elma/046-4000/nut-3-8/dp/1209855?Ntt=046-4000

Colin
www.audiomaintenance.com

Thanks!

Here's a little sneak preview of the first of my two EZ1073s. 

Unfortunately the wrong type of XLR socket was sent with my most recent parts order so currently I have no line out socket!  It'll be next week before it gets started up properly and tested, but given that it is as good as done, I couldn't resist a photo

Nice build!!

Got mine 2 peices also build,

first one started up with no problems, 2nd one has trubbles.

R23( 12R resistor) got hot and smoky. it's the limiting resistor for pre-ampstage 3.It draws hi currents......................
Power -ok led says ok but meassuring tels me that the 24V is real 19V and the 48V is real 43V. Trimpot for adjust doesn't respond.
Big guess: Short circuit in stage 3.................
First I will remove the 12R and meassure the voltages again without feeding the 3th stage. A new 12R must be ordered anyways, it degraded itself now to 8R.
Output transformer is also in this circuit, hopefully it isn't fried.

(BTW, I checked everything both 3x before powering up and meassured everything while installing components. And still........troublle)
The funny part in this all is I ordered 18 nice looking knobs for the EZ's, what did i become? 18 SMD resistors................, orderpicking faillure

More to come,

Happy building to ya all, fantastic kit Collin!

Check C2 and C3 are in the correct way round.

Check that there is not a short between the body of the 2N3055 (collector) and the ground plane (the screw hole pads are a bit small for the M4 screws and they can sometimes touch the Agnd).

Colin
www.audiomaintenance.com

If I have a bass player come over and record parts what is the best way to use this pre?
I know I can do microphone to cabinet but what about a direct version?

Direct out from bass amp into line in?  Can I plug the bass directly into the line in?  1/4 to xlr cable?

Thanks
-Scott

Line out from bass head, or use a DI box.

There is in fact now a new Carnhill DI transformer (VTB9072) which was not available when this was designed, otherwise I would have designed it into the circuit.

Colin
www.audiomaintenance.com

Seems to be as close as it can be !

http://www.tapeop.com/reviews/88/ez1073-500-500-series-preampeq/

If the link does not take you directly to the review then just go to the reviews section and search for ez1073

[A 1070L is simply a 1073 with the controls laid out differently - AFAIK]

Colin
www.audiomaintenance.com

nice review!  Congrats, they are really a great preamp!!!!

chrispsound said:

Click to expand...

I have a very newbish question about the grounding of the pcb board to the 1U case.  I noticed this pic and the Chris has used a wire on the ground of the xlrs to the main ground, but then I noticed the prototype build by Colin and he didn't ground that way.  What is the best way to ground the 1U build?

If I do use the xlr ground, do I need to connect the 1 pin to the ground of the xlr then daisy chain that over to the other xlrs to the main ground? 

Also, I know I need to take off the powder coating of the area were the screw for the main ground it going so it makes better contact with the case.  Do I need to do that with the xlr mounts? 

Thanks.

HELP!!!

ok, I powered one of my ez1073's on to calibrate the 48volts and output.  I plugged it in and started with the 48 volts.  I have the 48 volts on and put my leads for my multimeter on the line input connector.... I put one of leads on the "+48v" tab and the other on the "Agnd" tab.  There was a spark and I quickly took my leads off.  Then the 7824 voltage regulator started smoking.  I unplugged the unit...............then I waited and plugged it back in.......it started smoking again.  Can anyone tell me what I should do and/or what I did wrong?  I am guessing I need to get another 7824 voltage regulator.

I have these metal pieces with two feet.  Do these go into the slots right of the line input transformer (DC Feeds)?

Is this going to be sufficient for the 7824 voltage regulator?

http://www.mouser.com/ProductDetail/ROHM-Semiconductor/BA17824T/?qs=4kLU8WoGk0tve0p5C29gvk92nQGsOjR6Lz3PV6yQMAI%3d

If someone could help me ....I would much appreciate it.  I am freaking out.....there was smoke.  Man, I really hope I didn't fry everything. 

Dan

Can anyone give a lost soul some guidance?  I don't want to go further with any of my two 1073 until I am sure I won't further mess anything up.  I appreciate any advise. 

Dan

Brotastic said:

HELP!!!

ok, I powered one of my ez1073's on to calibrate the 48volts and output.  I plugged it in and started with the 48 volts.  I have the 48 volts on and put my leads for my multimeter on the line input connector.... I put one of leads on the "+48v" tab and the other on the "Agnd" tab. 

Click to expand...

SO you're saying you put the meter probes on te places in the attached drawing, or somewhere else?

Did you know that your multimeter works properly before starting this testing, or is it the first time you've used it?

There was a spark and I quickly took my leads off.  Then the 7824 voltage regulator started smoking.  I unplugged the unit...............then I waited and plugged it back in.......it started smoking again.  Can anyone tell me what I should do and/or what I did wrong?  I am guessing I need to get another 7824 voltage regulator.

Click to expand...

yes I would say so.

I have these metal pieces with two feet.  Do these go into the slots right of the line input transformer (DC Feeds)?

Click to expand...

Yep - but unless you want to hook up some other device you don't need to use them

Is this going to be sufficient for the 7824 voltage regulator?

http://www.mouser.com/ProductDetail/ROHM-Semiconductor/BA17824T/?qs=4kLU8WoGk0tve0p5C29gvk92nQGsOjR6Lz3PV6yQMAI%3d

Click to expand...

I believe that one will be fine - 1A is enough I think

If someone could help me ....I would much appreciate it.  I am freaking out.....there was smoke.  Man, I really hope I didn't fry everything. 

Dan

Click to expand...

Don't panic - hopefully all that has happened is that the 7824 needs replacing.  Sounds like a short somewhere in the 48V circuit, but I am no expert at this stuff so you may want to wait for a firmer answer.  Have you checked to make sure there's no continuity between 48v and ground

Edit : Ignore all that.  The 7824 has nothing to do with the 48V circuit - that is regulated by the TL783

You still need to double check everywhere with your multimeter to make sure you  don't have a short to ground on the 24V section of the circuit...

Could you have somehow shorted the 24V rail to the ground rail when you were trying to verify if the 48V rail was ok?

Hi! I just finished my first 1073 (minus the knobs ) and gave it a test run and everything was good! No smoke or burnt smells, oh, and it did sound amazing! Was completely blown away!

Noob questions:
- The one thing that is annoying is the output wich is way too hot! Do I just need to calibrate the output trim or is there anything else I need to do?

- Also, reading a few post regarding multimeters and smoke, I am a bit scared of calibrating the +48V. Is this such an important step? In wich way does this affect the unit/mic/sound?

Thanks in advance and sorry if these questions were answered before but couldn't find any answers!

EDIT: Found the post where Slenderchap mentions "measure the voltage across R26". How would I go about measuring this value?

rob_gould said:

Brotastic said:

HELP!!!

ok, I powered one of my ez1073's on to calibrate the 48volts and output.  I plugged it in and started with the 48 volts.  I have the 48 volts on and put my leads for my multimeter on the line input connector.... I put one of leads on the "+48v" tab and the other on the "Agnd" tab. 

Click to expand...

SO you're saying you put the meter probes on te places in the attached drawing, or somewhere else?  Yes, the same places. 

Did you know that your multimeter works properly before starting this testing, or is it the first time you've used it? Yes, it works.  I tested all of the components with the same multimeter before I soldered them in.  I will note that I am a novice at this.  This is my second build.  My first build was 4 Classic Audio of Illinois VP 312.  I am using a brand new Fluke 115.  This is my first time using this meter, but I have used other meters in the past 

There was a spark and I quickly took my leads off.  Then the 7824 voltage regulator started smoking.  I unplugged the unit...............then I waited and plugged it back in.......it started smoking again.  Can anyone tell me what I should do and/or what I did wrong?  I am guessing I need to get another 7824 voltage regulator.

Click to expand...

yes I would say so. Yup, that last part was rhetorical.

I have these metal pieces with two feet.  Do these go into the slots right of the line input transformer (DC Feeds)?

Click to expand...

Yep - but unless you want to hook up some other device you don't need to use them.  Ok, thank you.  That is good to know.  What devices could you hook up to these points? 

Is this going to be sufficient for the 7824 voltage regulator?

http://www.mouser.com/ProductDetail/ROHM-Semiconductor/BA17824T/?qs=4kLU8WoGk0tve0p5C29gvk92nQGsOjR6Lz3PV6yQMAI%3d

Click to expand...

I believe that one will be fine - 1A is enough I think.  Ok, Thank you, 

If someone could help me ....I would much appreciate it.  I am freaking out.....there was smoke.  Man, I really hope I didn't fry everything. 

Dan

Click to expand...

Don't panic - hopefully all that has happened is that the 7824 needs replacing.  Sounds like a short somewhere in the 48V circuit, but I am no expert at this stuff so you may want to wait for a firmer answer.  Have you checked to make sure there's no continuity between 48v and ground. I will check that this weekend, Thanks.

Edit : Ignore all that.  The 7824 has nothing to do with the 48V circuit - that is regulated by the TL783

You still need to double check everywhere with your multimeter to make sure you  don't have a short to ground on the 24V section of the circuit...

Could you have somehow shorted the 24V rail to the ground rail when you were trying to verify if the 48V rail was ok?

Click to expand...

I could have, but I don't know what I did wrong.  I will check all the solder points.  I haven't had a chance to touch this thing due to sessions.  The 7824 was the only one smoking and not the TL783.  If someone can verify that these would be sufficient replacements (http://www.mouser.com/ProductDetail/ROHM-Semiconductor/BA17824T/?qs=4kLU8WoGk0tve0p5C29gvk92nQGsOjR6Lz3PV6yQMAI%3d) I will re-solder the new ones.  Could switching the multimeter probes cause the short...polarities...red instead of black and vice versa?  I remember doing it the way you have in the picture you have, but I could have done it the other way.  Thank you for responding to the post.  I appreciate your input very much. 

No, black instead of red can't do anything ( you will just read a neg voltage value where you might read a positive one). BUT I remember once when I was a total novice testing between the + and - of power rails in the ampermeter position...THAT was a short !... bye, bye, power transformer... And it was on the HT rail off a stereo tube amp...

pyjaman said:

No, black instead of red can't do anything ( you will just read a neg voltage value where you might read a positive one). BUT I remember once when I was a total novice testing between the + and - of power rails in the ampermeter position...THAT was a short !... bye, bye, power transformer... And it was on the HT rail off a stereo tube amp...

Click to expand...

Cool, that is what I thought.  What is the ampermeter position.  I just put my meter to read voltage and put the probes on one of the wholes for the "+48v" tab and the other on the "Agnd" tab.  Do you think I damaged my power transformer?  Thanks for your reply to my post.  I very much appreciate it. 

macakinho said:

Hi! I just finished my first 1073 (minus the knobs ) and gave it a test run and everything was good! No smoke or burnt smells, oh, and it did sound amazing! Was completely blown away!

Noob questions:
- The one thing that is annoying is the output wich is way too hot! Do I just need to calibrate the output trim or is there anything else I need to do?

- Also, reading a few post regarding multimeters and smoke, I am a bit scared of calibrating the +48V. Is this such an important step? In wich way does this affect the unit/mic/sound?

Thanks in advance and sorry if these questions were answered before but couldn't find any answers!

EDIT: Found the post where Slenderchap mentions "measure the voltage across R26". How would I go about measuring this value?

Click to expand...

anyone? please?  :-[

Why would you be afraid of calibrating the 48v?  Is it worth cutting a corner to damage an expensive studio mic?  put the voltmeter on it and adjust as needed...