[BUILD] 1176LN Rev D DIY

[tronnyjenkins]

Have you checked your DC voltages against the MNATS schematic on his site?

Start there.  Then we can trace the signal, see where it dies.

I think I read these all correctly...

Q1
G 0.00
S 0.00
D 0.00

Q2
E 0.54
C 1.79
B 1.05

Q3
E 1.17
C 11.43
B 1.79

Q4
E 0.43
C 4.84
B 1.01

Q5
E 2.72
C 25.74
B 3.27

Q6
E 2.21
C 2.72
B 27.05

Q7
E 3.93
C 14.78
B 4.43

Q8
E 14.15
C 29.75
B 14.78

Q9
E 2.83
C 16.87
B 3.40

Q10
E 16.30
C 29.75
B 16.87

Q11
G 0.00
S 0.42
D 6.89

Q12
E -0.20
C 4.91
B 0.41

Q13
E -0.40
C 3.85
B -0.90

Q14
E 10.82
C 29.65
B 11.43

 

[Echo North]

Have you checked your DC voltages against the MNATS schematic on his site?

Start there.  Then we can trace the signal, see where it dies.

I think I read these all correctly...

Q1
G 0.00
S 0.00
D 0.00

Q2
E 0.54
C 1.79
B 1.05

Q3
E 1.17
C 11.43
B 1.79

Q4
E 0.43
C 4.84
B 1.01

Q5
E 2.72
C 25.74
B 3.27

Q6
E 2.21
C 2.72
B 27.05

Q7
E 3.93
C 14.78
B 4.43

Q8
E 14.15
C 29.75
B 14.78

Q9
E 2.83
C 16.87
B 3.40

Q10
E 16.30
C 29.75
B 16.87

Q11
G 0.00
S 0.42
D 6.89

Q12
E -0.20
C 4.91
B 0.41

Q13
E -0.40
C 3.85
B -0.90

Q14
E 10.82
C 29.65
B 11.43

Are any off?

Your Q1 gate should not be 0.  It should be a neg value.  That suggests a wiring error.

Mike

 

[jplebre]

Ffarrel, the only thing I have to say is that the transformer (ip+op) together may create oscillation problems. Keyword is may, as I'm not sure if it's a problem with this build, but I think it "may" because it does have a lot of gain.

Also, I read somewhere that you would need a different power supply, not the built in ones, but Echo North can pitch in if the 2 boards can be wired from the secondaries toroidal in parallel.

 

[ffarrell]

Ffarrel, the only thing I have to say is that the transformer (ip+op) together may create oscillation problems. Keyword is may, as I'm not sure if it's a problem with this build, but I think it "may" because it does have a lot of gain.

Also, I read somewhere that you would need a different power supply, not the built in ones, but Echo North can pitch in if the 2 boards can be wired from the secondaries toroidal in parallel.

Looks like you can do it. 

But the board is required to power two units with one transformer? So I can't stuff both boards and dual wire them?

The separate power supply is not required, but suggested to reduce component count. You can still power two boards each stuffed with power supply components from a single transformer.

You can see an example of a stereo unit wired with the separate power supply board in the photos posted on Reply #21 above.

Please take note of my AC warning above. I believe that many people just ignore the warnings on my page.

 

[tronnyjenkins]

Have you checked your DC voltages against the MNATS schematic on his site?

Start there.  Then we can trace the signal, see where it dies.

I think I read these all correctly...

Q1
G 0.00
S 0.00
D 0.00

Q2
E 0.54
C 1.79
B 1.05

Q3
E 1.17
C 11.43
B 1.79

Q4
E 0.43
C 4.84
B 1.01

Q5
E 2.72
C 25.74
B 3.27

Q6
E 2.21
C 2.72
B 27.05

Q7
E 3.93
C 14.78
B 4.43

Q8
E 14.15
C 29.75
B 14.78

Q9
E 2.83
C 16.87
B 3.40

Q10
E 16.30
C 29.75
B 16.87

Q11
G 0.00
S 0.42
D 6.89

Q12
E -0.20
C 4.91
B 0.41

Q13
E -0.40
C 3.85
B -0.90

Q14
E 10.82
C 29.65
B 11.43

Are any off?

Your Q1 gate should not be 0.  It should be a neg value.  That suggests a wiring error.

Mike

Man, I don't know what I've done wrong. I double checked the wiring today, and resoldered all points. Still nothing, and the Q1 still appears to be wrong.

 

[Echo North]

Do you have DC @ pad 18?  It leaves the Qbias pot there and ends up at pad 7 where you should have DC as well.  It'll be a negative value.

 

[tronnyjenkins]

Do you have DC @ pad 18?  It leaves the Qbias pot there and ends up at pad 7 where you should have DC as well.  It'll be a negative value.

Yes sir-
Pad 18= -3.6 mV
Pad 7= -6 mV

Also- update to my Q1 reading. My DMM was being a bit crazy before... that or I was.
G= -4.86 mV
S= .10 mV
D= .10 mV

 

[Echo North]

-4.86 mV?  Are you sure it's not V? 

 

[Echo North]

Have a look at the schematic.

R35 and R60 are in series between the -10VDC rail and ground.  They make a little voltage divider who's sole purpose to knock the -10VDC to a smaller value which is more manageable for dialing in the QBias which never needs to really be above -2VDC. 

So if you measure on the side of R35 that is not connected to R60, you'll see -10VDC (referencing ground).  The other side has the divided voltage, about -2.8 VDC by my calculations.

Sitting between that voltage and ground is the trimmer R59 for Qbias.  That should send a voltage of between -2.8VDC and 0VDC out of the wiper  depending on where the screw is.  That wiper is connected to pad 18 which is connected by wire to pad 7 (through the attack/release pot and R7).

So you should be able to adjust the qbias and get between -2.8VDC and 0VDC at pad 18.  If you're not you have a broken trimmer or there is an issue with R35/R60.

I'll be unable to access the internet till next Monday so good luck!  I'll check in and see how it's going Monday.

Mike

 

[tronnyjenkins]

Have a look at the schematic.

R35 and R60 are in series between the -10VDC rail and ground.  They make a little voltage divider who's sole purpose to knock the -10VDC to a smaller value which is more manageable for dialing in the QBias which never needs to really be above -2VDC. 

So if you measure on the side of R35 that is not connected to R60, you'll see -10VDC (referencing ground).  The other side has the divided voltage, about -2.8 VDC by my calculations.

Sitting between that voltage and ground is the trimmer R59 for Qbias.  That should send a voltage of between -2.8VDC and 0VDC out of the wiper  depending on where the screw is.  That wiper is connected to pad 18 which is connected by wire to pad 7 (through the attack/release pot and R7).

So you should be able to adjust the qbias and get between -2.8VDC and 0VDC at pad 18.  If you're not you have a broken trimmer or there is an issue with R35/R60.

I'll be unable to access the internet till next Monday so good luck!  I'll check in and see how it's going Monday.

Mike

Weird. I am starting to think I need a new DMM. I had it set to measure up to 200 mV (since I wasn't getting anything on a higher setting), and that is where the measurements earlier came from. Now, I re-measured and have different values. I did adjust R59 a bit.

R35 (non R60 side)= -9.65 VDC
R35 (R60 side)= -2.25 VDC
Pad 18= -2.28 VDC
Pad 7= -2.03 VDC
Q1, G= -1.8 VDC

I have no idea what is up with this meter, but it was also acting strange the other day.
Still not passing audio, unfortunately. And, I have a couple of other suspect values on Q6, and it seems like Q4 and Q14 are as well (switched values, according to the site I'm comparing to?)

 

[Echo North]

Have a look at the schematic.

R35 and R60 are in series between the -10VDC rail and ground.  They make a little voltage divider who's sole purpose to knock the -10VDC to a smaller value which is more manageable for dialing in the QBias which never needs to really be above -2VDC. 

So if you measure on the side of R35 that is not connected to R60, you'll see -10VDC (referencing ground).  The other side has the divided voltage, about -2.8 VDC by my calculations.

Sitting between that voltage and ground is the trimmer R59 for Qbias.  That should send a voltage of between -2.8VDC and 0VDC out of the wiper  depending on where the screw is.  That wiper is connected to pad 18 which is connected by wire to pad 7 (through the attack/release pot and R7).

So you should be able to adjust the qbias and get between -2.8VDC and 0VDC at pad 18.  If you're not you have a broken trimmer or there is an issue with R35/R60.

I'll be unable to access the internet till next Monday so good luck!  I'll check in and see how it's going Monday.

Mike

Weird. I am starting to think I need a new DMM. I had it set to measure up to 200 mV (since I wasn't getting anything on a higher setting), and that is where the measurements earlier came from. Now, I re-measured and have different values. I did adjust R59 a bit.

R35 (non R60 side)= -9.65 VDC
R35 (R60 side)= -2.25 VDC
Pad 18= -2.28 VDC
Pad 7= -2.03 VDC
Q1, G= -1.8 VDC

I have no idea what is up with this meter, but it was also acting strange the other day.
Still not passing audio, unfortunately. And, I have a couple of other suspect values on Q6, and it seems like Q4 and Q14 are as well (switched values, according to the site I'm comparing to?)

Ya your Qbias is not the issue.  I'm about to log off but in either this thread, or the A thread I walked someone through tracing the AC signal through the two gain stages to see where it dies.  It was in the past two weeks so it's in the last 2-3 pages.  Find that and walk through it.  See where your signal dies.

Well get you up and running!

Mike

 

[Echo North]

Here it is:
http://www.groupdiy.com/index.php?topic=29981.msg669833#msg669833

 

[jeff s.]

Hello,
I just finished building two of these Rev D kits at the same time and having some issues with calibration. On both units audio goes in and out with the VU registering this. My problem is that none of the trim pots are functioning. I have tried using the video from mnat and also the DMM way getting the volume up to .775V. When going the DMM way by the time I am at .775V my VU is pegged extremely hard which I don't think is normal at all. I noticed Looking at photos different people have there trim pots positioned different ways. Is there one proper way to have these set? I also found out that the trim pots are supposed to make a slight click sound when all the way to one side. Some of mine do some of mine do not. I have went over my wiring and soldering a few times and found nothing so far. I think if it was a mistake on soldering or a bad part only one unit would be acting this way but both are doing the same exact thing. I added a photo and have a few more if you want to see something on the unit.
Thanks in advance for any help anyone can give me on this.
Jeff

 

[sr1200]

Set the trimmers to about half to start out with.  If they are at min or max to start, calibration gets ugly.

 

[jeff s.]

Set the trimmers to about half to start out with.  If they are at min or max to start, calibration gets ugly.

Thanks for the reply but I really don't think that is my issue. I spent about 5 hours just on the q bias trying to get any type of reaction at all with no success. There were definitely points where the trim pots were at niether extreme. Any other suggestions would be great.

 

[tronnyjenkins]

Hello,
I just finished building two of these Rev D kits at the same time and having some issues with calibration. On both units audio goes in and out with the VU registering this. My problem is that none of the trim pots are functioning. I have tried using the video from mnat and also the DMM way getting the volume up to .775V. When going the DMM way by the time I am at .775V my VU is pegged extremely hard which I don't think is normal at all. I noticed Looking at photos different people have there trim pots positioned different ways. Is there one proper way to have these set? I also found out that the trim pots are supposed to make a slight click sound when all the way to one side. Some of mine do some of mine do not. I have went over my wiring and soldering a few times and found nothing so far. I think if it was a mistake on soldering or a bad part only one unit would be acting this way but both are doing the same exact thing. I added a photo and have a few more if you want to see something on the unit.
Thanks in advance for any help anyone can give me on this.
Jeff

First question: are you passing audio? I am having almost the exact same problem (q-bias either far left or pegged, can't calibrate) except I am not passing audio. If you look through the last couple of pages there may be some helpful stuff for you to try that I have already gone through. For example, checking voltages in the PSU and at the transistors and specific pads on the PCB. Other than that I can't be much help because I'm in the same boat... but at least you can do the things that I'm sure you'll be asked about when Echo North is back on Monday. Good luck man.

 

[jeff s.]

Thanks for the reply tronnyjenkins,
I am passing nice clean audio through both units. I will go ahead and do your suggestions and see what I come up with. I will keep you updated on my status. If anyone else has any other suggestions to add it would be greatly appreciated.
Thanks
Jeff

 

[tronnyjenkins]

OK, so I guess I am being stupid, but I compared transistor voltages today to the actual MNATS ones. My Q11 aND Q12 are off and everything else is right within reason. Anyone have ideas of what might be amiss? I know Echo North won't be back until Monday... My "10.56V" is more like 17V, and the "9.26V" on Q12 is more like 16-17V as well...

 

[Sillen]

Recently put together the 1176 and it seems like no power is coming in, the lamp doesn't light up and I can't measure any dc voltage from anything on the pcb really. The problem is probably in the wiring from the transformer I guess? I used a terminal strip which had 6 inputs on each side and I split it in half, do you think this could affect something? (to connect the secondaries to the pcb)

 

[mnats]

Anyone have ideas of what might be amiss?

It will be one or more of the things listed in the FAQ linked from the first post. Since you have physical access to the unit you are best placed to find out.