[BUILD] New FET/RACK Official Help Thread - Please read first post!

[Echo North]

I found the problem. I deserve a big slap . The issue was a missing resistor  LOL  :-[ (r8, which was hidden below the orange drop cap. )

I mostly wasted your time but I did learn a lot!  Many many thanks for your extremely valuable help and time.

Glad you found it!

 

[Mkvy83]

Hey so I just finished building the 1176 Rev D and calibrated it yesterday after letting it warm up for awhile. Today I noticed some screws were loose on the Main pcb brackets that connect to the chassis. When I tightened them back in, and turned on the 1176 today the VU meter is hitting +2 db with no signal going through it, attack off, releases CCW, ratio at 20:1, and meter on GR.  Would i need to recalibrate the compressor due to lose chassis screws on the brackets or can I just adjust the meter back to zero and it'll be fine?

 

[Echo North]

Hey so I just finished building the 1176 Rev D and calibrated it yesterday after letting it warm up for awhile. Today I noticed some screws were loose on the Main pcb brackets that connect to the chassis. When I tightened them back in, and turned on the 1176 today the VU meter is hitting +2 db with no signal going through it, attack off, releases CCW, ratio at 20:1, and meter on GR.  Would i need to recalibrate the compressor due to lose chassis screws on the brackets or can I just adjust the meter back to zero and it'll be fine?

I would probably re-calibrate.

 

[TDJ]

Hey all, sad story ahead. This weekend during a session, we were moving a few pieces of gear into our studio B, and one of the clients knocked my Rev A off of a chair from about 15" off of the ground. Now I'm having an issue where I have a very faint signal, and my output knob has very little affect on the volume. The compression, attack, release etc all seem to be working properly. It's just a very faint signal. Any ideas on where to start? Thanks.

 

[Echo North]

Hey all, sad story ahead. This weekend during a session, we were moving a few pieces of gear into our studio B, and one of the clients knocked my Rev A off of a chair from about 15" off of the ground. Now I'm having an issue where I have a very faint signal, and my output knob has very little affect on the volume. The compression, attack, release etc all seem to be working properly. It's just a very faint signal. Any ideas on where to start? Thanks.

Maybe the output pot got torn off a bit?  Start here:

Set your unit to:
Input: 12 O’Clock
Output: 12 O’Clock
Attack: GR OFF
Release: Full CW
Ratio: 20:1
Meter: GR
Signal: Sine 1kHz @ 0dBu (0.775 VAC across input + and -)

With your DMM measure your AC at the following test points using the chassis as you reference (black probe).

-Input XLR +
-TP1
-TP15
-TP17
-Output Transformer BRN
-Output XLR +

 

[Kevin Prochnow]

Hello people!

My Rev A is killing voltage and obscuring my input signal between TP1 and TP15, in the signal preamp section. I have replaced the Q1FET multiple times. Power supply seems fine. PLEASE HELP!!

 

[Echo North]

Hello people!

My Rev A is killing voltage and obscuring my input signal between TP1 and TP15, in the signal preamp section. I have replaced the Q1FET multiple times. Power supply seems fine. PLEASE HELP!!

What about with no Q1 FET in there? Still not signal at TP15?

 

[TDJ]

Maybe the output pot got torn off a bit?  Start here:

Set your unit to:
Input: 12 O’Clock
Output: 12 O’Clock
Attack: GR OFF
Release: Full CW
Ratio: 20:1
Meter: GR
Signal: Sine 1kHz @ 0dBu (0.775 VAC across input + and -)

With your DMM measure your AC at the following test points using the chassis as you reference (black probe).

-Input XLR +
-TP1
-TP15
-TP17
-Output Transformer BRN
-Output XLR +
[/quote

INPUT, TP1, AND TP15 are where they're supposed to be. TP 17 is reading virtually nothing at .009. Then BRN and Output + we have .420 (I'm assuming low since they aren't getting the proper signal earlier in the circuit). Thanks in advance!

 

[Echo North]

Maybe the output pot got torn off a bit?  Start here:

Set your unit to:
Input: 12 O’Clock
Output: 12 O’Clock
Attack: GR OFF
Release: Full CW
Ratio: 20:1
Meter: GR
Signal: Sine 1kHz @ 0dBu (0.775 VAC across input + and -)

With your DMM measure your AC at the following test points using the chassis as you reference (black probe).

-Input XLR +
-TP1
-TP15
-TP17
-Output Transformer BRN
-Output XLR +
[/quote

INPUT, TP1, AND TP15 are where they're supposed to be. TP 17 is reading virtually nothing at .009. Then BRN and Output + we have .420 (I'm assuming low since they aren't getting the proper signal earlier in the circuit). Thanks in advance!

Check your output pot. Maybe remove and test it.

 

[TDJ]

Check your output pot. Maybe remove and test it.

Good call, two broken legs. Not completely sure how that happened. After some internet research, looks like it's not an easy pot to find. Is there a way I can purchase one from you guys directly?

 

[Kevin Prochnow]

What about with no Q1 FET in there? Still not signal at TP15?

Just took it out and checked and still shows low voltage at tp15 (100mV when i think its supposed to be about 4V?)

 

[Echo North]

Good call, two broken legs. Not completely sure how that happened. After some internet research, looks like it's not an easy pot to find. Is there a way I can purchase one from you guys directly?

Yup, shoot us an email.

 

[Echo North]

Just took it out and checked and still shows low voltage at tp15 (100mV when i think its supposed to be about 4V?)

Ya.

You got something bad in that first amp section.  The voltages in the signal preamp should line up with this:

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

Anything off with Q2 or Q3?

Mike

 

[TDJ]

Yup, shoot us an email.

Got my new output pot in today, and all is well again! Hopefully it won't be dropped off of a chair again anytime soon. Thanks for the help! Now off to build my LOLA!

 

[Kevin Prochnow]

Ya.

You got something bad in that first amp section.  The voltages in the signal preamp should line up with this:

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

Anything off with Q2 or Q3?

Mike

The voltages at Q2 and Q3 are off. The 30V supply on the other side of R17 is present and correct.

 

[Echo North]

The voltages at Q2 and Q3 are off. The 30V supply on the other side of R17 is present and correct.

Something is off in there. Bad resistor/cap value, solder joint, lifted pad (check continuity), or bad transistor.

If you're convinced everything is ok we can fire you out a couple transistors.

 

[nickcion]

Hey, this is from a ways back.. just back in town and at the bench.. My Q1 was pulled per our previous discussion, which then gave us signal at T1.

Did you want me to replace Q1 and then do the test below? or do the test without replacing? just wanna be sure before I put in this transistor.

Set your unit to:
Input: 12 O’Clock
Output: 12 O’Clock
Attack: GR OFF
Release: Full CW
Ratio: 20:1
Meter: GR
Signal: Sine 1kHz @ 0dBu

With your DMM measure your AC at the following test points using the chassis as you reference (black probe).

-Input XLR +
-TP1
-TP15
-TP17
-Output Transformer BRN
-Output XLR +

 

[Kevin Prochnow]

Something is off in there. Bad resistor/cap value, solder joint, lifted pad (check continuity), or bad transistor.

If you're convinced everything is ok we can fire you out a couple transistors.

There is a tiny lead stuck in the middle hole of the Q1 footprint from one of the times I've replaced it, but I don't believe that is the issue since I am still able to connect all 3 leads when I put a different one in, and this signal issue was happening before I took the original Q1 transistor out in the first place. The continuity around Q1 all checks out, and I will check other areas. If you could send replacement transistors for Q2 and Q3, that would be cool, too. 

 

[Echo North]

There is a tiny lead stuck in the middle hole of the Q1 footprint from one of the times I've replaced it, but I don't believe that is the issue since I am still able to connect all 3 leads when I put a different one in, and this signal issue was happening before I took the original Q1 transistor out in the first place. The continuity around Q1 all checks out, and I will check other areas. If you could send replacement transistors for Q2 and Q3, that would be cool, too.

Shoot us an email.

 

[Echo North]

Hey, this is from a ways back.. just back in town and at the bench.. My Q1 was pulled per our previous discussion, which then gave us signal at T1.

Did you want me to replace Q1 and then do the test below? or do the test without replacing? just wanna be sure before I put in this transistor.

Start by testing without.