[BUILD] 1176LN Rev D DIY

[mgalimbe]

You've either got something wrong in that first signal amp stage or a wiring error withx your output pot.

With the unit on and no signal, measure the DC V of the transistor leads in the "Signal Preamp".

http://mnats.net/files/1176REVD_VOLTS.pdf

Q3 and Q4.

Triple check your output wiring. What is the resistance in ohms between C7 - and ground (0V in the power supply)?

Mike
[/quote

Hi mike
Well something funny happened when I plugged the unit in the light on the meter came on for the +4 and 8 button but then it went out.  I then went on to test  q3&4 and got nothing I tested by  placing the black lead on ct and touching the red lead to either side of the transistor.  I also checked the resistance of c7 and have nothing.

Thanks
Mike g

 

[Echo North]

You've either got something wrong in that first signal amp stage or a wiring error withx your output pot.

With the unit on and no signal, measure the DC V of the transistor leads in the "Signal Preamp".

http://mnats.net/files/1176REVD_VOLTS.pdf

Q3 and Q4.

Triple check your output wiring. What is the resistance in ohms between C7 - and ground (0V in the power supply)?

Mike
[/quote

Hi mike
Well something funny happened when I plugged the unit in the light on the meter came on for the +4 and 8 button but then it went out.  I then went on to test  q3&4 and got nothing I tested by  placing the black lead on ct and touching the red lead to either side of the transistor.  I also checked the resistance of c7 and have nothing.

Thanks
Mike g

Resistance of C7? Or do you mean you had no AC voltage there?

 

[Echo North]

Now you need to trace the signal level as described in my last post.

Mike

Hey Mike!

So I've rewired my input (again), and just sat down to do VAC measurements. I measured .775 V at pins 2 and 3 (black lead on 2, red on 3), and I plugged it in.

Internal side of the input XLR (pins 2/3): .304 V
Input of the TPad: .153 V
Output of TPad: .061 V
Input transformer input: .061 V
Input transformer output: .049 V
Input terminal PCB: .049 V
C7 pad + : fluctuates a whole lot?
C7 pad - : .879 V
Blue wire: 2.425 V

It seems like things are a little low from the input jack, but progressing nicely from there? Is it the input jack??

Thoughts??? Thanks again for all your help!

Once you established the input level between pin 2 and 3, what did you put your black probe on as a reference for the rest of the measurements?  0V on the power supply?

If you're getting a ton of fluctuation you have some oscillation in your first amp stage on in the output wiring.

Mike

I put the black lead on the 0V CT on the PCB. How would I be getting fluctuation? Faulty soldering of parts in the PCB? How should I address that?

EDIT My oscillation goes in and out, sometimes I get a solid reading at both pads at C7, sometimes I don't. I don't know if that helps..

Also the lower input level to the PCB is a problem right? Getting .04V instead of .06-.09?

As always thanks man!

I wouldn't worry too much about the input level. That's probably an issue with not having your Qbias set yet.  You need to figure out what is going on that is causing oscillations/drop outs at C7. If you feed a 1K, 0dB signal, have your GR OFF, and the in/out set to 12 o'clock you should be getting a lot more gain at C7, even with the slightly lower input.

You need to visually check all of the components in that section for value, orientation, and damage. If all that looks ok, you may consider removing Q1 to see if that get's you better signal, if that doesn't work, you'll may consider replacing Q2, Q3, and Q14.

Sorry this one has me stumped.

Mike

 

[mgalimbe]

You've either got something wrong in that first signal amp stage or a wiring error withx your output pot.

With the unit on and no signal, measure the DC V of the transistor leads in the "Signal Preamp".

http://mnats.net/files/1176REVD_VOLTS.pdf

Q3 and Q4.

Triple check your output wiring. What is the resistance in ohms between C7 - and ground (0V in the power supply)?

Mike
[/quote

Hi mike
Well something funny happened when I plugged the unit in the light on the meter came on for the +4 and 8 button but then it went out.  I then went on to test  q3&4 and got nothing I tested by  placing the black lead on ct and touching the red lead to either side of the transistor.  I also checked the resistance of c7 and have nothing.

Thanks
Mike g

Resistance of C7? Or do you mean you had no AC voltage there?

hi mike the resistance of c7- and the CT terminal is 132.8k I must have done something wrong the first time I did this.

 

[cfleming1989]

I wouldn't worry too much about the input level. That's probably an issue with not having your Qbias set yet.  You need to figure out what is going on that is causing oscillations/drop outs at C7. If you feed a 1K, 0dB signal, have your GR OFF, and the in/out set to 12 o'clock you should be getting a lot more gain at C7, even with the slightly lower input.

You need to visually check all of the components in that section for value, orientation, and damage. If all that looks ok, you may consider removing Q1 to see if that get's you better signal, if that doesn't work, you'll may consider replacing Q2, Q3, and Q14.

Sorry this one has me stumped.

Mike

Hey Mike

So I was just going through checking all of my components. Everything checks out, however C3 and C6 on the mnats schematic are reading 200 pF, however the capacitors I was given and placed onto C3/6 have "221" printed on them, meaning 220 pF right?  Is that the problem??

EDIT All of my other capacitors have the correct value, just so you know.

I've attached a picture of my PCB board, if you don't mind checking it out... Seriously thanks so much man, sending as many good vibes your way as I can.

 

[Echo North]

I wouldn't worry too much about the input level. That's probably an issue with not having your Qbias set yet.  You need to figure out what is going on that is causing oscillations/drop outs at C7. If you feed a 1K, 0dB signal, have your GR OFF, and the in/out set to 12 o'clock you should be getting a lot more gain at C7, even with the slightly lower input.

You need to visually check all of the components in that section for value, orientation, and damage. If all that looks ok, you may consider removing Q1 to see if that get's you better signal, if that doesn't work, you'll may consider replacing Q2, Q3, and Q14.

Sorry this one has me stumped.

Mike

Hey Mike

So I was just going through checking all of my components. Everything checks out, however C3 and C6 on the mnats schematic are reading 200 pF, however the capacitors I was given and placed onto C3/6 have "221" printed on them, meaning 220 pF right?  Is that the problem??

EDIT All of my other capacitors have the correct value, just so you know.
EDIT 2 Q8/9/10/12/13 all have 2N3707 printed on the board, but the parts I have are 2N3708. Thoughts?

I've attached a picture of my PCB board, if you don't mind checking it out... Seriously thanks so much man, sending as many good vibes your way as I can.

All of those components are fine.

That soldering is very suspect. I would suspect a cold joint, missed solder joint, or heat damaged component. You should reflow your joints and perhaps consider sending it in for repair.

Mike

 

[Echo North]

You've either got something wrong in that first signal amp stage or a wiring error withx your output pot.

With the unit on and no signal, measure the DC V of the transistor leads in the "Signal Preamp".

http://mnats.net/files/1176REVD_VOLTS.pdf

Q3 and Q4.

Triple check your output wiring. What is the resistance in ohms between C7 - and ground (0V in the power supply)?

Mike
[/quote

Hi mike
Well something funny happened when I plugged the unit in the light on the meter came on for the +4 and 8 button but then it went out.  I then went on to test  q3&4 and got nothing I tested by  placing the black lead on ct and touching the red lead to either side of the transistor.  I also checked the resistance of c7 and have nothing.

Thanks
Mike g

Resistance of C7? Or do you mean you had no AC voltage there?

hi mike the resistance of c7- and the CT terminal is 132.8k I must have done something wrong the first time I did this.

Maybe I mis-typed. I was looking for an AC voltage there.

 

[mgalimbe]

You've either got something wrong in that first signal amp stage or a wiring error withx your output pot.

With the unit on and no signal, measure the DC V of the transistor leads in the "Signal Preamp".

http://mnats.net/files/1176REVD_VOLTS.pdf

Q3 and Q4.

Triple check your output wiring. What is the resistance in ohms between C7 - and ground (0V in the power supply)?

Mike
[/quote

Hi mike
Well something funny happened when I plugged the unit in the light on the meter came on for the +4 and 8 button but then it went out.  I then went on to test  q3&4 and got nothing I tested by  placing the black lead on ct and touching the red lead to either side of the transistor.  I also checked the resistance of c7 and have nothing.

Thanks
Mike g

Resistance of C7? Or do you mean you had no AC voltage there?

hi mike the resistance of c7- and the CT terminal is 132.8k I must have done something wrong the first time I did this.

Maybe I mis-typed. I was looking for an AC voltage there.

Ok in that case I have no voltage there (c7-). I just went back and did the test that you suggested we do when I first built the power supply (it passed back then).  but now I get no readings on CT & 30v or CT & 10v. I do have power coming in to the unit at the power connector. but I don't know where to look to see where I'm loosing power and I don't really understand what could have happened from when I initially did the test to now.

 

[Echo North]

You've either got something wrong in that first signal amp stage or a wiring error withx your output pot.

With the unit on and no signal, measure the DC V of the transistor leads in the "Signal Preamp".

http://mnats.net/files/1176REVD_VOLTS.pdf

Q3 and Q4.

Triple check your output wiring. What is the resistance in ohms between C7 - and ground (0V in the power supply)?

Mike
[/quote

Hi mike
Well something funny happened when I plugged the unit in the light on the meter came on for the +4 and 8 button but then it went out.  I then went on to test  q3&4 and got nothing I tested by  placing the black lead on ct and touching the red lead to either side of the transistor.  I also checked the resistance of c7 and have nothing.

Thanks
Mike g

Resistance of C7? Or do you mean you had no AC voltage there?

hi mike the resistance of c7- and the CT terminal is 132.8k I must have done something wrong the first time I did this.

Maybe I mis-typed. I was looking for an AC voltage there.

Ok in that case I have no voltage there (c7-). I just went back and did the test that you suggested we do when I first built the power supply (it passed back then).  but now I get no readings on CT & 30v or CT & 10v. I do have power coming in to the unit at the power connector. but I don't know where to look to see where I'm loosing power and I don't really understand what could have happened from when I initially did the test to now.

Are you measure for DC there?

 

[mgalimbe]

You've either got something wrong in that first signal amp stage or a wiring error withx your output pot.

With the unit on and no signal, measure the DC V of the transistor leads in the "Signal Preamp".

http://mnats.net/files/1176REVD_VOLTS.pdf

Q3 and Q4.

Triple check your output wiring. What is the resistance in ohms between C7 - and ground (0V in the power supply)?

Mike
[/quote

Hi mike
Well something funny happened when I plugged the unit in the light on the meter came on for the +4 and 8 button but then it went out.  I then went on to test  q3&4 and got nothing I tested by  placing the black lead on ct and touching the red lead to either side of the transistor.  I also checked the resistance of c7 and have nothing.

Thanks
Mike g

Resistance of C7? Or do you mean you had no AC voltage there?

hi mike the resistance of c7- and the CT terminal is 132.8k I must have done something wrong the first time I did this.

Maybe I mis-typed. I was looking for an AC voltage there.

Ok in that case I have no voltage there (c7-). I just went back and did the test that you suggested we do when I first built the power supply (it passed back then).  but now I get no readings on CT & 30v or CT & 10v. I do have power coming in to the unit at the power connector. but I don't know where to look to see where I'm loosing power and I don't really understand what could have happened from when I initially did the test to now.

Are you measure for DC there?

No AC voltage

 

[Echo North]

Your power supply runs on DC. Are you testing the +30V and -10V with your DMM DC setting?

 

[mgalimbe]

Yes I'm testing the +30v & -10V on the DC setting on my DMM sorry I thought i had it on AC but it was in fact on the DC setting.

 

[Echo North]

Yes I'm testing the +30v & -10V on the DC setting on my DMM sorry I thought i had it on AC but it was in fact on the DC setting.

And you're not getting any DC reading there? Did you blow a fuse?

 

[mgalimbe]

Yes I'm testing the +30v & -10V on the DC setting on my DMM sorry I thought i had it on AC but it was in fact on the DC setting.

And you're not getting any DC reading there? Did you blow a fuse?

no I checked the fuse I'm getting 120 v AC on the back side of the power connector so its at least getting to there. and no I"m not getting any readings there.

 

[Echo North]

Yes I'm testing the +30v & -10V on the DC setting on my DMM sorry I thought i had it on AC but it was in fact on the DC setting.

And you're not getting any DC reading there? Did you blow a fuse?

no I checked the fuse I'm getting 120 v AC on the back side of the power connector so its at least getting to there. and no I"m not getting any readings there.

So no light in your meter?

Do you have V AC between the 0V and either AC side where the power secondary connects to the main PCB?

 

[mgalimbe]

Yes I'm testing the +30v & -10V on the DC setting on my DMM sorry I thought i had it on AC but it was in fact on the DC setting.

And you're not getting any DC reading there? Did you blow a fuse?

no I checked the fuse I'm getting 120 v AC on the back side of the power connector so its at least getting to there. and no I"m not getting any readings there.

So no light in your meter?

Do you have V AC between the 0V and either AC side where the power secondary connects to the main PCB?

i posted earlier that I had a light on and then it went out and I do not have an AC reading on the CT to either AC sides on the PCB.
It seems to be going from bad to worse for me....

 

[Echo North]

Yes I'm testing the +30v & -10V on the DC setting on my DMM sorry I thought i had it on AC but it was in fact on the DC setting.

And you're not getting any DC reading there? Did you blow a fuse?

no I checked the fuse I'm getting 120 v AC on the back side of the power connector so its at least getting to there. and no I"m not getting any readings there.

So no light in your meter?

Do you have V AC between the 0V and either AC side where the power secondary connects to the main PCB?

i posted earlier that I had a light on and then it went out and I do not have an AC reading on the CT to either AC sides on the PCB.
It seems to be going from bad to worse for me....

You've got the "Off" switch on the meter board out?

 

[mgalimbe]

Yes I'm testing the +30v & -10V on the DC setting on my DMM sorry I thought i had it on AC but it was in fact on the DC setting.

And you're not getting any DC reading there? Did you blow a fuse?

no I checked the fuse I'm getting 120 v AC on the back side of the power connector so its at least getting to there. and no I"m not getting any readings there.

So no light in your meter?

Do you have V AC between the 0V and either AC side where the power secondary connects to the main PCB?

i posted earlier that I had a light on and then it went out and I do not have an AC reading on the CT to either AC sides on the PCB.
It seems to be going from bad to worse for me....

You've got the "Off" switch on the meter board out?

Yes

 

[Echo North]

Do you have VAC between the 0V on the main PCB either of the power transformer primaries on the switch? Be VERY careful.

 

[mgalimbe]

Do you have VAC between the 0V on the main PCB either of the power transformer primaries on the switch? Be VERY careful.

if the  primary wires are the ones that go from the power transformer to the middle connectors on the switch then no I do not have any power  there.