[BUILD] 1176LN Rev D DIY

[kerrymckenna14]

You need to measure some DC voltages with your compressor on, no signal needed. 

What is your DC at pad 19 and what happens to it when you turn the qbias trimmer? What is the highest and lowest you can get it. Use the CT/0V pad as your reference/common.

Mike

Hi Mike,

I measured thoses values and they are as follows,

Pad 19 with CT as common -
Regularly is was reading -0.650-ish DC volts (it kept fluctuating.)
Highest it went to was -0.001 DC Volts.
Lowest went well under -2 DC Volts but I didn't want to go much farther as the trimmer was clicking. 

Does this help?
Also, when I was measuring the DC of it regularly it was slowly decreasing.  I would start at -.650-ish and slowly make its was to -.7 and higher. 

Kerry

 

[Echo North]

What about the "Gate" pad of Q1?

Same DC V test.

 

[kerrymckenna14]

What about the "Gate" pad of Q1?

Same DC V test.

Highest seems to be reading -0.001DC volts and the highest seems to be reading -1.8DC Volts.

 

[Echo North]

What about the "Gate" pad of Q1?

Same DC V test.

Highest seems to be reading -0.001DC volts and the highest seems to be reading -1.8DC Volts.

Sounds normal. Start your qbias adjustment with the trimmer at -1.8V DC the rotate towards 0.

Try this method to set the QBias:
https://www.youtube.com/watch?v=0Uuk1Y7M2D8

 

[kerrymckenna14]

What about the "Gate" pad of Q1?

Same DC V test.

Highest seems to be reading -0.001DC volts and the highest seems to be reading -1.8DC Volts.

Sounds normal. Start your qbias adjustment with the trimmer at -1.8V DC the rotate towards 0.

Try this method to set the QBias:
https://www.youtube.com/watch?v=0Uuk1Y7M2D8

I followed that guide, still no luck.

Had the signal coming in at .775 VAC, I brought the trimmer all the way towards 0 and it did not budge.

Any idea why?

 

[Echo North]

What about the "Gate" pad of Q1?

Same DC V test.

Highest seems to be reading -0.001DC volts and the highest seems to be reading -1.8DC Volts.

Sounds normal. Start your qbias adjustment with the trimmer at -1.8V DC the rotate towards 0.

Try this method to set the QBias:
https://www.youtube.com/watch?v=0Uuk1Y7M2D8

I followed that guide, still no luck.

Had the signal coming in at .775 VAC, I brought the trimmer all the way towards 0 and it did not budge.

Any idea why?

Are you measuring your output? What is your output signal? Can you get it to 2.45V AC as described in our calibration?

Mike

 

[kerrymckenna14]

What about the "Gate" pad of Q1?

Same DC V test.

Highest seems to be reading -0.001DC volts and the highest seems to be reading -1.8DC Volts.

Sounds normal. Start your qbias adjustment with the trimmer at -1.8V DC the rotate towards 0.

Try this method to set the QBias:
https://www.youtube.com/watch?v=0Uuk1Y7M2D8

I followed that guide, still no luck.

Had the signal coming in at .775 VAC, I brought the trimmer all the way towards 0 and it did not budge.

Any idea why?

Are you measuring your output? What is your output signal? Can you get it to 2.45V AC as described in our calibration?

Mike

I pointed that out in my original post, I don't seem to be getting any signal out.  It will jump up to .300 V AC and then drop to zero.
This is with the output cranked as high as it could go.

 

[Echo North]

Oh that's a different issue.

Easiest way to check for signal is to use a DMM set to read AC volts.

Turn the attack pot to the GR off position. Set your input and output to mid rotation and your release fully CW.  Feed the unit a 1kHz, 0dB signal (0.775VAC).  Confirm you have 0.775VAC between input pins 2 and 3.  Now follow the signal using ground and you common reference point (where you put the black lead).  You can attach it to ground at the 0V/CT terminal at the PCB power supply.

Measure the VAC against ground at:

1. T-Pad input + (should be about half of 0.775)
2. T-Pad output +  (should be even smaller)
3. Input transformer primary + (should be the same as step 2)
4. Input transformer secondary + (getting smaller)
5. At the Input + terminal at the main PCB (should be roughly 0.06 to 0.09VAC)
6. C7 + pad (should be much larger now, around 2.0 VAC)
7. C7- pad (should be the same as  #6)
8. Blue wire on output transformer (should be a large VAC number)

Report back. That will help determine where the signal is dying.

Mike

 

[kerrymckenna14]

Oh that's a different issue.

Easiest way to check for signal is to use a DMM set to read AC volts.

Turn the attack pot to the GR off position. Set your input and output to mid rotation and your release fully CW.  Feed the unit a 1kHz, 0dB signal (0.775VAC).  Confirm you have 0.775VAC between input pins 2 and 3.  Now follow the signal using ground and you common reference point (where you put the black lead).  You can attach it to ground at the 0V/CT terminal at the PCB power supply.

Measure the VAC against ground at:

1. T-Pad input + (should be about half of 0.775)
2. T-Pad output +  (should be even smaller)
3. Input transformer primary + (should be the same as step 2)
4. Input transformer secondary + (getting smaller)
5. At the Input + terminal at the main PCB (should be roughly 0.06 to 0.09VAC)
6. C7 + pad (should be much larger now, around 2.0 VAC)
7. C7- pad (should be the same as  #6)
8. Blue wire on output transformer (should be a large VAC number)

Report back. That will help determine where the signal is dying.

Mike

Hey Mike,

I got those measurements for you,

1. T-Pad input + = No change from .775
2. T-Pad output + = .146
3. Input transformer primary + = .146
4. Input transformer secondary + = .84
5. At the Input + terminal at the main PCB = .08
6. C7 + pad = .4
7. C7- pad = .4
8. Blue wire on output transformer = have shrink tubing over it, can't measure!

Everything was reading perfect except for the C7 pads, but the wire on my input transformer frayed and detached with all the movement, which in turn trying to get around everything the tpad input frayed.  I striped and soldered them back and in place, and these are the readings I have now.  Very frustrated.

 

[Echo North]

Welcome to DIY.

You have something wrong in the box labeled "Signal Preamp".

http://mnats.net/files/1176LN_REVD_V2.2_DOC.pdf

Bad solder, misplaced component, damaged part.  Check your voltages there:
http://mnats.net/files/1176REVD_VOLTS.pdf

Google to figure out which lead is which.

Mike

 

[kerrymckenna14]

Welcome to DIY.

You have something wrong in the box labeled "Signal Preamp".

http://mnats.net/files/1176LN_REVD_V2.2_DOC.pdf

Bad solder, misplaced component, damaged part.  Check your voltages there:
http://mnats.net/files/1176REVD_VOLTS.pdf

Google to figure out which lead is which.

Mike

Hey Mike,

Checked those.  All resistors are reading correctly except for R4 and R10.  I've double checked the band code colours, and also used a band code calculator to triple check that they are the correct resistors, and they are (270 Ohms and 10k Ohms).  They keep reading 0 Ohms and then spitting out random number.  R4 particularly keeps reading 12k.  R10 keeps going all over the place.

I tested the capacitors also and double checked the readings on the caps themselves.  They're reading correctly on the capacitor themselves, but the readings seem to be going up as far as 150 uF for the 100uF caps. 

I tidied up my soldering a small bit to see if it would help but no change. Heres a pic of the Signal Preamp section.

Does this give any insight to what may be wrong?

Kerry

 

[kerrymckenna14]

Heres another

 

[Echo North]

That's not what I asked for. Also, without a deeper understanding of electronics, you cannot accurately measure components while soldered on the PCB. They are interacting.

I need to know the DC voltages for the B,E,C of Q2, Q3, and Q14.

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

Mike

 

[kerrymckenna14]

That's not what I asked for. Also, without a deeper understanding of electronics, you cannot accurately measure components while soldered on the PCB. They are interacting.

I need to know the DC voltages for the B,E,C of Q2, Q3, and Q14.

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

Mike

Sorry about that Mike! It was 3am here and I was stressing 

Q2 -> B-C is reading 0.687 V, B-E is reading 0.691V.
Q3 -> B-C is reading 0.691V, B-E is reading 0.695V.
Q14 -> B-C is reading 0.692, B-E is reading 0.697V.

 

[Echo North]

That's not what I asked for. Also, without a deeper understanding of electronics, you cannot accurately measure components while soldered on the PCB. They are interacting.

I need to know the DC voltages for the B,E,C of Q2, Q3, and Q14.

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

Mike

Sorry about that Mike! It was 3am here and I was stressing 

Q2 -> B-C is reading 0.687 V, B-E is reading 0.691V.
Q3 -> B-C is reading 0.691V, B-E is reading 0.695V.
Q14 -> B-C is reading 0.692, B-E is reading 0.697V.

Each leg on it's own, referencing 0V/CT.  Should be three readings per transistor.

Mike

 

[kerrymckenna14]

That's not what I asked for. Also, without a deeper understanding of electronics, you cannot accurately measure components while soldered on the PCB. They are interacting.

I need to know the DC voltages for the B,E,C of Q2, Q3, and Q14.

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

Mike

Sorry about that Mike! It was 3am here and I was stressing 

Q2 -> B-C is reading 0.687 V, B-E is reading 0.691V.
Q3 -> B-C is reading 0.691V, B-E is reading 0.695V.
Q14 -> B-C is reading 0.692, B-E is reading 0.697V.

Each leg on it's own, referencing 0V/CT.  Should be three readings per transistor.

Mike

Q2 -> B = 0.85, C1.2 = , E= 0.291
Q3 -> B= 1.2, C= 1.1, E = 1
Q14 -> B = 1.1, C = .791, E = 1.7

Very varied....

 

[kerrymckenna14]

That's not what I asked for. Also, without a deeper understanding of electronics, you cannot accurately measure components while soldered on the PCB. They are interacting.

I need to know the DC voltages for the B,E,C of Q2, Q3, and Q14.

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

Mike

Sorry about that Mike! It was 3am here and I was stressing 

Q2 -> B-C is reading 0.687 V, B-E is reading 0.691V.
Q3 -> B-C is reading 0.691V, B-E is reading 0.695V.
Q14 -> B-C is reading 0.692, B-E is reading 0.697V.

Each leg on it's own, referencing 0V/CT.  Should be three readings per transistor.

Mike

Q2 -> B = 0.85, C1.2 = , E= 0.291
Q3 -> B= 1.2, C= 1.1, E = 1
Q14 -> B = 1.1, C = .791, E = 1.7

Very varied....

What do you think I'll have to do Mike?

 

[Echo North]

Has to be a measuring error. Are you measuring DC? The unit is on?

The collector of Q14 is connected directly to the 30V DC rail. You should be seeing 30V DC there.

I'm kind of lost. Did you test you power supply?

We do offer a repair service.
http://www.hairballaudio.com/build-support-services

Mike

 

[kerrymckenna14]

Has to be a measuring error. Are you measuring DC? The unit is on?

The collector of Q14 is connected directly to the 30V DC rail. You should be seeing 30V DC there.

I'm kind of lost. Did you test you power supply?

We do offer a repair service.
http://www.hairballaudio.com/build-support-services



Mike

Sorry Mike I didn't realise the unit had to be power on.  Did the measurements again and I can't get any reading from Q14 and the B & C of Q3?

Would this shed any light on what may be wrong?

 

[Echo North]

Has to be a measuring error. Are you measuring DC? The unit is on?

The collector of Q14 is connected directly to the 30V DC rail. You should be seeing 30V DC there.

I'm kind of lost. Did you test you power supply?

We do offer a repair service.
http://www.hairballaudio.com/build-support-services



Mike

Sorry Mike I didn't realise the unit had to be power on.  Did the measurements again and I can't get any reading from Q14 and the B & C of Q3?

Would this shed any light on what may be wrong?

Test your power supply. The +30V DC and -10V DC rail. Described in the "Building the Power Supply" section of the guide, at the end.

Mike