[BUILD] 1176 Rev A - Back to the beginning...

[Echo North]

Hey,

So I built my new Rev A kit. When I powered it on however, R32 started smoking. I immediately turned it off.

I already built a rev A before, but it has never worked. It's always given this terrible distortion (even in bypassed). If I remember correctly, I have also replaced R32 there because it was looking funky.

I planned on building a new (good) rev A so I could check my old one for mistakes.. but this one does seem to have problems as well. We've checked all the voltages before, we've checked all the resistors on color code, we've checked all wiring... nothing seems to be out of place, nothing seems to be shorted.. Any ideas?  :-\

I'm Europe based if that says anything..

(Also I have built 2 rev.D kits but they've been working and sounding beautifully from the start. I have no idea why my 2 rev A (V1.2.5) kits seem to be giving problems. The same problems apparently, although I haven't tested if my new rev A hs the same terrible distortion as my previous one. Maybe there is some kind of mistake in the Rev A assembly guide or anything?  :-\ I'm running out of ideas)

http://tinypic.com/r/23uokcp/8

http://tinypic.com/r/33412qo/8

Also, at the 30V test point I'm getting 29.69V and at the -10V i'm getting -9.71V. In my other rev A kit these values are also correct.

If it was wired improperly at the output, or for any reason if R32 smoked, even if you fixed the reason for that there is a good chance Q6 was fried.  Any time R32 smokes, I'd replace Q6 too.

If the output is wired correct to the PCB (check agains the PCB in this doc if the codes are blocked by the header):
http://mnats.net/files/1176REVA_125_DOCUMENTATION.pdf

then I would have a look at the R values around Q6 and make sure they are right.  Also check you DC voltages around Q6, after replacing it and R5.  Make sure you're putting Q6 in correctly and have it heat sinked.

report back!

Mike

 

[Mr.Franky]

Hey,

So I built my new Rev A kit. When I powered it on however, R32 started smoking. I immediately turned it off.

I already built a rev A before, but it has never worked. It's always given this terrible distortion (even in bypassed). If I remember correctly, I have also replaced R32 there because it was looking funky.

I planned on building a new (good) rev A so I could check my old one for mistakes.. but this one does seem to have problems as well. We've checked all the voltages before, we've checked all the resistors on color code, we've checked all wiring... nothing seems to be out of place, nothing seems to be shorted.. Any ideas?  :-\

I'm Europe based if that says anything..

(Also I have built 2 rev.D kits but they've been working and sounding beautifully from the start. I have no idea why my 2 rev A (V1.2.5) kits seem to be giving problems. The same problems apparently, although I haven't tested if my new rev A hs the same terrible distortion as my previous one. Maybe there is some kind of mistake in the Rev A assembly guide or anything?  :-\ I'm running out of ideas)

http://tinypic.com/r/23uokcp/8

http://tinypic.com/r/33412qo/8

Also, at the 30V test point I'm getting 29.69V and at the -10V i'm getting -9.71V. In my other rev A kit these values are also correct.

If it was wired improperly at the output, or for any reason if R32 smoked, even if you fixed the reason for that there is a good chance Q6 was fried.  Any time R32 smokes, I'd replace Q6 too.

If the output is wired correct to the PCB (check agains the PCB in this doc if the codes are blocked by the header):
http://mnats.net/files/1176REVA_125_DOCUMENTATION.pdf

then I would have a look at the R values around Q6 and make sure they are right.  Also check you DC voltages around Q6, after replacing it and R5.  Make sure you're putting Q6 in correctly and have it heat sinked.

report back!

Mike

Hey Mike,

The output is (as you can see in the picture) wired correctly to the PCB. I've checked all the R values in the signal line amp. They're all correct. I've tested every resistor before placing them on the pcb too, for your information.

I've desoldered Q6 like you suggested and it doesn't seem to be 'funky' in any way, it was seated and soldered correctly too. I'll go to the shop and replace R32 and Q6 and then see what happens. I'll check the DC values around Q6 after replacing it and R32. You said something about R5, was that a typo? I suppose you either meant R32 or Q5?

I'll report back when it's all replaced etc

 

[Echo North]

Yes R32, or whatever the smoking one is.

Q6 would not look funky if it was internally damaged.  It would just smoke the resistor and make the output noisy.

I'd definitely replace that Q.  Not sure why it died in the first place though.

Mike

 

[Mr.Franky]

Hey,

So I built my new Rev A kit. When I powered it on however, R32 started smoking. I immediately turned it off.

I already built a rev A before, but it has never worked. It's always given this terrible distortion (even in bypassed). If I remember correctly, I have also replaced R32 there because it was looking funky.

I planned on building a new (good) rev A so I could check my old one for mistakes.. but this one does seem to have problems as well. We've checked all the voltages before, we've checked all the resistors on color code, we've checked all wiring... nothing seems to be out of place, nothing seems to be shorted.. Any ideas?  :-\

I'm Europe based if that says anything..

(Also I have built 2 rev.D kits but they've been working and sounding beautifully from the start. I have no idea why my 2 rev A (V1.2.5) kits seem to be giving problems. The same problems apparently, although I haven't tested if my new rev A hs the same terrible distortion as my previous one. Maybe there is some kind of mistake in the Rev A assembly guide or anything?  :-\ I'm running out of ideas)

http://tinypic.com/r/23uokcp/8

http://tinypic.com/r/33412qo/8

Also, at the 30V test point I'm getting 29.69V and at the -10V i'm getting -9.71V. In my other rev A kit these values are also correct.

If it was wired improperly at the output, or for any reason if R32 smoked, even if you fixed the reason for that there is a good chance Q6 was fried.  Any time R32 smokes, I'd replace Q6 too.

If the output is wired correct to the PCB (check agains the PCB in this doc if the codes are blocked by the header):
http://mnats.net/files/1176REVA_125_DOCUMENTATION.pdf

then I would have a look at the R values around Q6 and make sure they are right.  Also check you DC voltages around Q6, after replacing it and R5.  Make sure you're putting Q6 in correctly and have it heat sinked.

report back!

Mike

Hey Mike,

The output is (as you can see in the picture) wired correctly to the PCB. I've checked all the R values in the signal line amp. They're all correct. I've tested every resistor before placing them on the pcb too, for your information.

I've desoldered Q6 like you suggested and it doesn't seem to be 'funky' in any way, it was seated and soldered correctly too. I'll go to the shop and replace R32 and Q6 and then see what happens. I'll check the DC values around Q6 after replacing it and R32. You said something about R5, was that a typo? I suppose you either meant R32 or Q5?

I'll report back when it's all replaced etc

Hey,

Good news!!! My 2 rev A kits (which had some issue) are now up and running and sounding absolutely fantastic!!

Here's the story, just in case anybody else has the same issues:

When i built my first revA, I didn't have any signal on the output XLR while trying to calibrate the kit. That told me something was wrong, but I didn't know what. I sent in the kit with a tech friend, and he noticed Q6 being wiggly. He desoldered it and we saw the legs were bent underneath the transistor, which obviously gave a short and caused R32 to fry. He replaced it, and also replaced R32.
When I got home I put some audio through it and all i had was this terrible distortion modulating on the signal no matter how i set the input/ouput control (even in bypass as well..). He visited me to track down the problem with an oscilloscope, but couldn't find anything out of place though.
Now, several months later, I noticed that we replaced R32 with the wrong value. We replaced the 39ohm resistor with a 39kohm resistor. So I desoldered the R32 and for the sake of it replaced Q6 as well. Since then this kit was working beautifully!

For the second RevA I built (just now), I had the smoking R32. All I had to do there was what Mike told me to do in previous posts. I replaced both Q6 and R32 and this did the job. This one is now working some vocal magic as well!

I'm not sure why R32 burnt in the first place.. maybe I just received a bad 2N3053 (Q6) , maybe it died in transport, maybe I damaged it while solderen.. no idea.

Point is, my 2 faulty revA kits are now working and they're working very, very good!

Thanks for the support, Mike!

 

[Echo North]

Awesome!

Could be a bad Q6 or the legs shorted on the second one as well.  We're going to start shipping spacers for Q6 that should prevent that.

Mike

 

[Mr.Franky]

Awesome!

Could be a bad Q6 or the legs shorted on the second one as well.  We're going to start shipping spacers for Q6 that should prevent that.

Mike

Hey Mike,

The Q6 legs definitely weren't shorted on the second one. I'm guessing just a bad Q6, doesn't matter, they work!

Regards,

 

[yourdudeness]

Hi, everyone, first post here, just showing off my completed rev. a. It's working beautifully and sounds awesome. Hats off to mnats and hairball for putting this together. This thread was very useful too.

 

[darthgustafson]

Hello. I built the Hairball Rev A and am running into problems at the calibration stage. The Input is not affected when I turn up the pot. I am reading 2.75 at the input and I have checked my wiring and solder joints. The output works and affects the meter but not the input. Any help would be appreciated.

 

[Echo North]

Hello. I built the Hairball Rev A and am running into problems at the calibration stage. The Input is not affected when I turn up the pot. I am reading 2.75 at the input and I have checked my wiring and solder joints. The output works and affects the meter but not the input. Any help would be appreciated.

http://groupdiy.com/index.php?topic=29981.msg724759#msg724759

 

[darthgustafson]

Thank you for the response. I am measuring 2.3 at R80 and R60. If this is the issue how do I go about fixing the issue? If this is normal I followed it through and it measured 2.3 throughout to the ratio board. I can get through all steps until meter calibration until I run into issues. It will read the same when switching from off and attack full clockwise. I have repeated all calibration steps many times and end up with the same results.

 

[darthgustafson]

I can null adjust but not able to do the gain reduction meter portion.

 

[darthgustafson]

The more I try this I feel it may be that the attack is what is not working. I don't see anything wrong with the wiring though. Any suggestions?

 

[darthgustafson]

I rewired the compressor this morning to make sure everything was done properly and I'm still having issues. At the calibrating meter stage I can't get it to show a 10db drop. I can get the output to read .775 VAC with attack off, but when I turn the attack on I can only bring the input up to 1.0 VAC. The VAC reading is the sam when turning the attack on and off.

 

[Echo North]

I rewired the compressor this morning to make sure everything was done properly and I'm still having issues. At the calibrating meter stage I can't get it to show a 10db drop. I can get the output to read .775 VAC with attack off, but when I turn the attack on I can only bring the input up to 1.0 VAC. The VAC reading is the sam when turning the attack on and off.

So your Qbias adjust meant when ok?

Mike

 

[darthgustafson]

yes it did.

 

[Echo North]

yes it did.

And you used TP10 and TP11 to set the DC Null adjust?

Did you set the meter back to zero after you put the jumper back in place AFTER setting null adjust?

 

[darthgustafson]

Yes I did. I have attempted this 3 times going quite slowly as to do every step as precise as I am able.

 

[Echo North]

Yes I did. I have attempted this 3 times going quite slowly as to do every step as precise as I am able.

How are your voltages against the schematic with voltages?  In the GR meter section?

They'll be a little off because you are not calibrated correctly, but how off?

Your using the jumper correctly?

http://mnats.net/files/1176REVA_125_VOLTAGES.pdf

 

[germoju]

Hello !!

I got an issue with I think, a Vu Meter (8027).
I got 2x Dual 1176 here. 1x Dual Rev D and 1x Dual Rev A.

A few days ago, 1 LED of each Vu Meter of my Rev A died after month without problems...
I opened the case and make some mesure on the Vu Meter.

One is 6,2V AC, but the other is 14V !! They are from the same alimentation ! And they have same resistor (1,8k / 5W)

So I opened my dual Rev D. The 2 Vumeter have the same value. 6,0V AC

So I unplug my VuMeter who indicate 14V and unplug the other too. I put the wire from the 14V to the other meter and make a new mesure : 6,2V !!!
I re-plug it on the other Vu MEter : 14V !! (??)


Do you have an idea ? What do you think ?

EDIT : picture added
and I try to power one VuMeter of the revD with aire from VuMter of my revA : I got 5,5V
If I re-plug the wires on the VuMeter of revA, I have 14V again...

 

[darthgustafson]

My jumper has been in the correct position but I'm finding issues with the voltage at Q7,8,9, & 10. They are orientated properly but the voltage seems to be off.
Q7 - 24.6, .8, 3
Q8 - 24.6, 29.6, 25
Q9 - 4.6, 5.7, 4.1
Q10 - 5.7, 29.6, 5.3