simsung

Hairball Lola Problems
« on: February 15, 2013, 08:13:57 AM »
hey,

yesterday i used valentinsday to build my new Hairball Lola preamp.
a friend who already build several devices helped me , and we double checked every detail to not make any mistake. - you know where this leads to, right?

after testing today of course the lola doesnt work properly.
i hear lots of noises and the usefull signal that comes from the microphone is very quiet, but hearable.
the meters show me that the signal from the mic is loud enough, so i guess i should something to do with the output. but since i ´m not a pro , its just my guessing.

does anyone have any clue or idea, that could help me with that problem , before i check every single detail again?

thanks
simon


okgb

Re: Hairball Lola Problems
« Reply #1 on: February 15, 2013, 09:26:34 AM »
 Not sure where in the circuit the meter taps off , but if that is working as you observe must be farther down
the chain  , double check output xfmr wiring , hopefully something easy like  getting a color wrong
opamps you are using both known to be good ?  double checking the resister may take a little more time
if you didn't measure before installing , check also for no shorts or solder bridges underneath the input xfmr
good luck & skill
GKB Audio / Greg Boboski

bruce0

Re: Hairball Lola Problems
« Reply #2 on: February 15, 2013, 10:37:12 AM »
Well you double checked everything... but just in case.  Here is a couple of things to check.

1) Use a loupe or magnifier (unless you have great eyes) and inspect every solder joint for "solder bridges" and "cold solder joints" (good google search terms if they are unfamiliar.
2) Since the meter works, pay special attention to the output circuits, and since it is noise and low output, check the ground connections.
3) Put a voltmeter on the power after the input diodes.

Low output and noise... Check the transformer ground.

Post pictures of the back and front of the board.

Sorry if these are obvious.
"it was like heaven on earth, all those transformers" - cj

simsung

Re: Hairball Lola Problems
« Reply #3 on: February 15, 2013, 05:25:40 PM »
thank you for your quick reply.
i found that the problem sits in the meter bridge, because,when i disconnect it from the main board, everything works fine..
now it will be much easier to find the problem.
thanks alot!!
« Last Edit: February 15, 2013, 05:31:06 PM by simsung »

simsung

Re: Hairball Lola Problems
« Reply #4 on: February 17, 2013, 04:44:14 PM »
thanks for your help.
i checked the solder joints on the meter bridge and corrected some.
that was the whole problem.
now it works perfectly!!

gemini86

Re: Hairball Lola Problems
« Reply #5 on: February 17, 2013, 06:54:21 PM »
As usual, it's the humans that cause a lot of the problems in life. :D
- Rodney

"...you better call Kenny Loggins, 'cause you're in the danger zone."

okgb

Re: Hairball Lola Problems
« Reply #6 on: February 18, 2013, 08:55:53 AM »
Yeah , I gotta say my eyesight is not so great that I rely on the solder mask sometimes ,
more & more I have to treat it like surgery and pay attention to every joint as I do them ,
not a bad thing just takes a little longer
GKB Audio / Greg Boboski

Re: Hairball Lola Problems
« Reply #7 on: March 05, 2013, 12:50:42 PM »
Please help:

I build a lola and it smoked out on me during a session.  Worked for 2h and then stopped.  The DOAs were very hot.  R37, R32, R31 look fried.  Is it the DOAs?  Have I fried the whole thing?

Hairball Audio

Re: Hairball Lola Problems
« Reply #8 on: March 05, 2013, 12:59:34 PM »
Please help:

I build a lola and it smoked out on me during a session.  Worked for 2h and then stopped.  The DOAs were very hot.  R37, R32, R31 look fried.  Is it the DOAs?  Have I fried the whole thing?

Yikes!

I'm going to move your question to the support thread now which is located here:
http://www.groupdiy.com/index.php?topic=47671.0

That'll keep things tidy in here.

Mike
Hairball Audio, LLC
DIY Parts and Kits
http://hairballaudio.com/shop

Top secret stuff and upcoming releases:
http://facebook.com/hairballaudio
http://twitter.com/HairballAudio/

Dmeek78

Re: Hairball Lola Problems
« Reply #9 on: March 15, 2019, 03:31:52 PM »
Hi I have no idea how to use this forum but here is my problem: I have a friend from out of town who is a electrical engineer that built a Lola for me  (but he doesn’t have a series 500 rack to test it). Yesterday I finally got it back and snapped it in to try it. The main 3 buttons lit up blue when pressed but no matter what I did, I couldn’t get sound (I tried swapping my converter cables, plugged into the line in the front, tried the xlr in the back, checked the settings in my daw...). No matter what I did my other preamp works with ease but no sound with the Lola. Any suggestions? Thanks -Daniel


TillM

Re: Hairball Lola Problems
« Reply #10 on: March 15, 2019, 03:35:53 PM »
Which OP-Amps do you use ?

Hairball Audio

Re: Hairball Lola Problems
« Reply #11 on: March 15, 2019, 04:04:12 PM »
Which OP-Amps do you use ?

Ya this.  Did he build the op-amps? What are they?
Hairball Audio, LLC
DIY Parts and Kits
http://hairballaudio.com/shop

Top secret stuff and upcoming releases:
http://facebook.com/hairballaudio
http://twitter.com/HairballAudio/

Dmeek78

Re: Hairball Lola Problems
« Reply #12 on: March 16, 2019, 02:55:04 PM »
 The op amps I’m using  Are the BA512s

Hairball Audio

Re: Hairball Lola Problems
« Reply #13 on: March 18, 2019, 01:11:32 PM »
The op amps I’m using  Are the BA512s

Do you have any other op-amps you can try?  Much of the audio circuit is in the op-amps, so that's the easiest thing to test.
Hairball Audio, LLC
DIY Parts and Kits
http://hairballaudio.com/shop

Top secret stuff and upcoming releases:
http://facebook.com/hairballaudio
http://twitter.com/HairballAudio/

Dmeek78

Re: Hairball Lola Problems
« Reply #14 on: March 19, 2019, 01:11:29 PM »
I don’t have any extra op amps. I was wondering if it would help to upload a picture from a few angles?

TillM

Re: Hairball Lola Problems
« Reply #15 on: March 19, 2019, 01:38:18 PM »
Probably it could help.
You said the Meter works and the Signal is really low... hmm ... do you know somebody, who has some 2520 pin out DOAs?

Hairball Audio

Re: Hairball Lola Problems
« Reply #16 on: March 19, 2019, 06:28:53 PM »
I don’t have any extra op amps. I was wondering if it would help to upload a picture from a few angles?

You might have a bad BA512.  Take off the heatsinks and take a picture of both sides os the large output transistors on the op-amps.  We had a couple of badly oriented ones a few months ago.

Mike
Hairball Audio, LLC
DIY Parts and Kits
http://hairballaudio.com/shop

Top secret stuff and upcoming releases:
http://facebook.com/hairballaudio
http://twitter.com/HairballAudio/

Dmeek78

Re: Hairball Lola Problems
« Reply #17 on: March 27, 2019, 02:24:42 AM »
 OK so I hve a friend from out of town who put the Lola together for me  and I just gave it back to him as well as forwarded him the information you mentioned. I’ll update this when he updates me thanks.😉

Hairball Audio

Re: Hairball Lola Problems
« Reply #18 on: March 27, 2019, 01:29:10 PM »
OK so I hve a friend from out of town who put the Lola together for me  and I just gave it back to him as well as forwarded him the information you mentioned. I’ll update this when he updates me thanks.😉

Sounds good.
Hairball Audio, LLC
DIY Parts and Kits
http://hairballaudio.com/shop

Top secret stuff and upcoming releases:
http://facebook.com/hairballaudio
http://twitter.com/HairballAudio/

Re: Hairball Lola Problems
« Reply #19 on: May 04, 2019, 11:08:45 AM »
Sorry for the delay folks!
I took some pictures of the BD136 PNP transistors on the opamp boards as requested.
Here they are!
Any help would be wonderful.

My main concern is that I cannot find where +-15VDC enters the board. 
I did a resistance check from R22 on the +15VDC side and touched all the edge pads, but none resulted in direct contact.
I was able to successfully ohm our R22 to other nodes where +15VDC is supposed to be.  I just can't find the source of +15VDC.
This is also true for -15VDC using R23 as a reference.


 

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