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Snaper
Joined: Feb 28, 2014 Posts: 217 Location: Hungary
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Posted: Fri Jan 23, 2015 10:25 am Post subject:
Ring Mod Help |
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Hi Guys,
Just finished the Balanced Ring mod, for my Euro system.
Its powered from +/12V, and just to know, basically cutted the PCB in half, cause I didn't need a dual version. (Every trace is in place.)
My problem is that the out is tooooooo low.
I mean, I have to amplify it to hear something :S
Used MC1496, instead of LM.
Did anyone experienced the same problem?
What should I check first? |
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Snaper
Joined: Feb 28, 2014 Posts: 217 Location: Hungary
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Posted: Fri Jan 23, 2015 11:42 am Post subject:
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Measured a few things...weird :S
Nothing plugged in :
AC ins/outs : 0 V
DC in : there are voltages :O !!!! (-2,7v on Input B and +6,75v on Input A)
DC out : -10,32v
Something is wrong :S |
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Snaper
Joined: Feb 28, 2014 Posts: 217 Location: Hungary
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Posted: Sat Jan 24, 2015 12:06 am Post subject:
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Totally disconnected the DC inputs, and outputs, now, no sound, nothing :S
Nothing, even if fiddle with trimpots.
Should I drop the board to the trash or is it possible to fix this? |
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yusynth
Joined: Nov 24, 2005 Posts: 1314 Location: France
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Posted: Sat Jan 24, 2015 4:08 am Post subject:
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What do you input in the module ? _________________ Yves |
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yusynth
Joined: Nov 24, 2005 Posts: 1314 Location: France
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Posted: Sat Jan 24, 2015 4:12 am Post subject:
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Snaper wrote: | AC ins/outs : 0 V
DC in : there are voltages :O !!!! (-2,7v on Input B and +6,75v on Input A)
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This is quite normal
Snaper wrote: | DC out : -10,32v |
This is not normal. _________________ Yves |
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Snaper
Joined: Feb 28, 2014 Posts: 217 Location: Hungary
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Posted: Sat Jan 24, 2015 5:08 am Post subject:
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yusynth wrote: | What do you input in the module ? |
Your fantastic VCO
(Also from 12v) |
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Snaper
Joined: Feb 28, 2014 Posts: 217 Location: Hungary
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Posted: Sat Jan 24, 2015 5:09 am Post subject:
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yusynth wrote: |
Snaper wrote: | DC out : -10,32v |
This is not normal. |
Thats my problem to.
Should I measure all pins of the opamp?
I think there is some kind of problem with the buffer stage.
Tried it several TL072s...
Pin voltages would help you to track down the problem? |
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yusynth
Joined: Nov 24, 2005 Posts: 1314 Location: France
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Posted: Sat Jan 24, 2015 5:17 am Post subject:
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Do you use two VCO as sources ? one for each input ? Have you an oscilloscope ? Did you follow the trimming instructions ? _________________ Yves |
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Snaper
Joined: Feb 28, 2014 Posts: 217 Location: Hungary
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Posted: Sat Jan 24, 2015 6:37 am Post subject:
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yusynth wrote: | Do you use two VCO as sources ? |
Yes. Love them!
yusynth wrote: | one for each input ? |
Yes.
yusynth wrote: | Have you an oscilloscope ? |
Unfortunately, no...
yusynth wrote: | Did you follow the trimming instructions ? |
Yapp.
My voltages : (nothing plugged in)
TL072
pin 1 : -9,59
pin 2 : 0
pin 3 : 7,78
pin 4 : -12
pin 5: 0
pin 6 : -10,16
pin 7 : -10,33
pin 8 : 12
MC1496
pin 1 : -3,25
pin 2 : -3,98
pin 3 : -3,98
pin 4 : -3,26
pin 5 : -10,09
pin 6 : 9,87
pin 7 : 0
pin 8 : 7,36
pin 9 : 0
pin 10 : 7,36
pin 11 : 0
pin 12 : 9,94
pin 13 : 0
pin 14 : -12 |
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Snaper
Joined: Feb 28, 2014 Posts: 217 Location: Hungary
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Posted: Sat Jan 24, 2015 8:27 am Post subject:
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A good friend suggested me a test.
I've "audio checked" the pins of the TL072. (with a jack plug)
I can hear the signal in inputs, and I can hear it on Pin 1. That means, that the problem is with the second opamp stage.
I don't know what could be, cause the resistors are OK. |
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yusynth
Joined: Nov 24, 2005 Posts: 1314 Location: France
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Posted: Sat Jan 24, 2015 8:47 am Post subject:
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Considering that you measure 9.87V on pin 6 of the MC1496 and 9.94V on pin 12 (which seems normal), the values that you measure on pins 2 and 3 and consequently 1 of the TL072 are not what is expected.
What one would expect to read is :
pin 2 : 4.97V
pin 3 : 4.97V
pin 1 : 0.070V
as a matter of fact on pin 1 of the TL072 we must read the difference between the voltages at pins 12 and 6 of the MC1496: 9.94V-9.87V that is 0.070V.
Either the TL072 is dead or there is some kind of shortcut on pin 3 or 4 of the TL072... _________________ Yves |
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Snaper
Joined: Feb 28, 2014 Posts: 217 Location: Hungary
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Posted: Sat Jan 24, 2015 10:38 am Post subject:
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I've re-heated the joints, checked for shorts, etc.
Now its "kinda' " working, there is audible sound, but still extremly low, and I still have the -10.3v at the outs.
The problem is with the second opamp stage, cause I can measure around 5 volts on pin 1 of the TL074, and around 3v on pin 6, but on pin seven, there is -10 :S
Weird... |
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yusynth
Joined: Nov 24, 2005 Posts: 1314 Location: France
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Posted: Sat Jan 24, 2015 10:43 am Post subject:
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5V on pin 1 is much too high!
Did you check and change the TL072 _________________ Yves |
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Snaper
Joined: Feb 28, 2014 Posts: 217 Location: Hungary
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Posted: Sat Jan 24, 2015 10:53 am Post subject:
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yusynth wrote: | 5V on pin 1 is much too high!
Did you check and change the TL072 |
5,25 precisely.
Tried 4 diff TLs, its the same... |
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wackelpeter
Joined: May 05, 2013 Posts: 461 Location: germany
Audio files: 10
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Posted: Sat Jan 24, 2015 11:01 am Post subject:
Re: Ring Mod Help |
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Snaper wrote: | Hi Guys,
Just finished the Balanced Ring mod, for my Euro system.
Its powered from +/12V, and just to know, basically cutted the PCB in half, cause I didn't need a dual version. (Every trace is in place.)
My problem is that the out is tooooooo low.
I mean, I have to amplify it to hear something :S
Used MC1496, instead of LM.
Did anyone experienced the same problem?
What should I check first? |
seems like you didn't used the original PCB... correct? if this is a stripboard design or your own design... maybe it's a good idea to post some pics of both sides of the PCB... maybe a few more eyes looking at it can find the suspect...
...you know "can't see the wood for the trees" _________________ https://soundcloud.com/bastian-j |
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Snaper
Joined: Feb 28, 2014 Posts: 217 Location: Hungary
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Posted: Sat Jan 24, 2015 11:08 am Post subject:
Re: Ring Mod Help |
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wackelpeter wrote: | Snaper wrote: | Hi Guys,
Just finished the Balanced Ring mod, for my Euro system.
Its powered from +/12V, and just to know, basically cutted the PCB in half, cause I didn't need a dual version. (Every trace is in place.)
My problem is that the out is tooooooo low.
I mean, I have to amplify it to hear something :S
Used MC1496, instead of LM.
Did anyone experienced the same problem?
What should I check first? |
seems like you didn't used the original PCB... correct? if this is a stripboard design or your own design... maybe it's a good idea to post some pics of both sides of the PCB... maybe a few more eyes looking at it can find the suspect...
...you know "can't see the wood for the trees" |
Its the PCB from Yves, but just half of it...
In the other hands, I like sharing photos
HIRES :
https://www.dropbox.com/sh/nkro4gt3j1ph8x6/AAA1gTKnCnJNTTygEAUEx_yia?dl=0 |
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wackelpeter
Joined: May 05, 2013 Posts: 461 Location: germany
Audio files: 10
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Posted: Sat Jan 24, 2015 11:34 am Post subject:
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is this a slight short between pin 3 and 4 of your tl072?
what do you measure on pin 2 and 3 of the tl072 right know?
first with chip installed and then without? _________________ https://soundcloud.com/bastian-j |
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yusynth
Joined: Nov 24, 2005 Posts: 1314 Location: France
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Posted: Sat Jan 24, 2015 11:48 am Post subject:
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Once again can you measure the voltage on pin 6 and 12 of the MC1496. _________________ Yves |
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wackelpeter
Joined: May 05, 2013 Posts: 461 Location: germany
Audio files: 10
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Posted: Sat Jan 24, 2015 11:54 am Post subject:
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and btw is R11 an 15k resistor looks different to R19 to R21... ? i'm not good at reading those colour codes...
edit: could it be that this is a 15k resistor and R19 to R21 aren't...
checking with the 1k5 or 15K resistors in my box they start with brown for 1 and then green for 5 then followed by the code for multiplication and tolerance... don't know if there are different colour codes usual...
your's beginning with green and then brown look like they are something with 51... could be possible that i'm totally wrong _________________ https://soundcloud.com/bastian-j |
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Snaper
Joined: Feb 28, 2014 Posts: 217 Location: Hungary
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Posted: Sat Jan 24, 2015 12:31 pm Post subject:
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yusynth wrote: | Once again can you measure the voltage on pin 6 and 12 of the MC1496. |
pin 6 : 9,97
pin 12 : 9,84 |
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yusynth
Joined: Nov 24, 2005 Posts: 1314 Location: France
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Posted: Sat Jan 24, 2015 12:38 pm Post subject:
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You should have 0.070 at pin 1 of the TL072 check thoroughly all the components connected to pins 1,2 and 3 of the TL074, check for a short between tracks. Remove TL072 and repeat the measures at pin 1,2 and 3 of the TL072 _________________ Yves |
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Snaper
Joined: Feb 28, 2014 Posts: 217 Location: Hungary
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Posted: Sat Jan 24, 2015 12:50 pm Post subject:
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OUCH!
What a n0000b failure!
Those 15k resistors...are...51k ones...
I think I have "electro-dyslexia...
Yves, I am so so so sorry about this.
Replaced the 3 resistors and everything is working without any kind of glitch.
Actually sounds awesome!!!
Thanks for the help, and sorry again :S
Shame on me
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Snaper
Joined: Feb 28, 2014 Posts: 217 Location: Hungary
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Posted: Sat Jan 24, 2015 12:50 pm Post subject:
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wackelpeter wrote: | and btw is R11 an 15k resistor looks different to R19 to R21... ? i'm not good at reading those colour codes...
edit: could it be that this is a 15k resistor and R19 to R21 aren't...
checking with the 1k5 or 15K resistors in my box they start with brown for 1 and then green for 5 then followed by the code for multiplication and tolerance... don't know if there are different colour codes usual...
your's beginning with green and then brown look like they are something with 51... could be possible that i'm totally wrong |
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Snaper
Joined: Feb 28, 2014 Posts: 217 Location: Hungary
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Posted: Sat Jan 24, 2015 12:51 pm Post subject:
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yusynth wrote: | You should have 0.070 at pin 1 of the TL072 check thoroughly all the components connected to pins 1,2 and 3 of the TL074, check for a short between tracks. Remove TL072 and repeat the measures at pin 1,2 and 3 of the TL072 |
Now yes, all voltages are correct! |
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yusynth
Joined: Nov 24, 2005 Posts: 1314 Location: France
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Posted: Sat Jan 24, 2015 12:53 pm Post subject:
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all is fine then _________________ Yves |
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