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

[stringmike]

Hi. I just finished both a rev. A and D. My D works perfectly, but I have issues with my A.
Only the 20:1 ratio is working - when I change to other ratios, the meter still zeroes, but shows and makes no compression. I haven’t measured excactly, but I can’t hear any difference between bypass mode and the compressor engaged. I checked all the connectors between the ratio board and the main board, and all seems good. Any suggestions for troubleshooting?

 

[Echo North]

Hi. I just finished both a rev. A and D. My D works perfectly, but I have issues with my A.
Only the 20:1 ratio is working - when I change to other ratios, the meter still zeroes, but shows and makes no compression. I haven’t measured excactly, but I can’t hear any difference between bypass mode and the compressor engaged. I checked all the connectors between the ratio board and the main board, and all seems good. Any suggestions for troubleshooting?

Side-chain has kind of a cascading ladder thing happening. If only one ratio works, it's going to be 20:1.  Most likely you have a ratio PCB issue.

Set your compressor controls:

Input: 12 O’Clock
Output: 12 O’Clock
Attack: GR ON (fully CW)
Release: Full CW
Ratio: Check All
Meter: GR
Signal: Sine 1kHz @ 0dBu (0.775 VAC across input + and -)

1. With your DMM measure AC at TP22 for each ratio setting using the chassis as you reference (black probe).
2. With your DMM measure AC at the anode of CR2 for each ratio setting using the chassis as you reference (black probe). The anode is the positive lead and is the lead without the line.
3. With your DMM measure DC at TP21 for each ratio setting using the chassis as you reference (black probe).

Make sure to note #1 and #2 are AC and #3 is DC. Report those 3 voltages for each ratio.

Mike

 

[stringmike]

Thanks, Mike.
I’m in Europe, so it’s getting late, and I’ve left the studio. I’ll report back tomorrow.

 

[stringmike]

Okay, here we go:
AC @tp22:
4:1    .044v
8:1    .09v
12:1 .022v
20:1 .41v

AC @CR2
4:1    .6v
8:1  1.2v
12:1  .2v
20:1    3.6v

DC @tp21
4:1    -1.46
8:1    -2.3
12:1 -3.15
20:1 -5.85

 

[Echo North]

Okay, here we go:
AC @tp22:
4:1    .044v
8:1    .09v
12:1 .022v
20:1 .41v

AC @CR2
4:1    .6v
8:1  1.2v
12:1  .2v
20:1    3.6v

DC @tp21
4:1    -1.46
8:1    -2.3
12:1 -3.15
20:1 -5.85

It's really just your 12:1 ratio that looks bad.  Are 8 and 4:1 not compressing?

Check your ratio PCB, particularly around R19-R22.  Check all values, reflow solder, check pads, check soldering for the 12:1 switch.


Mike

 

[stringmike]

No, only 20:1 compresses. I’ll be back, when I’m back in the studio.

 

[stringmike]

Resistor values are correct, as far as I can see. Doesn’t everything look correct here?

 

[stringmike]

Soldering side:

 

[Echo North]

Pictures don't really help, it's usually something that needs to be tested with continuity. 

Pop the ratio PCB in from your working D. Does that fix it or same issue?

Mike

 

[stringmike]

Well, I had to hard-wire the ratio board to my D, because the CN10 was missing. The replacement  you sent has not been delivered yet, and tracking says it’s still in transit, with the latest registration Oct. 19th. So I had to do something  to have a working compressor

 

[stringmike]

Oh, I mixed up the ratio and attack/release boards. I tried to go through all the solder points before switching boards - and now it seems to work, although 8:1 didn’t work at one point, but then it came back again. Have you had idle switches?

 

[stringmike]

Now, everything seems to be fine with my rev. A. But now, all of a sudden, my D starts to crap out. It has worked before, calibrated and fine. But now it just farts, when I feed a bass signal to it. There meter shows what I hear. Any troubleshooting tips?

 

[beaustep]

Hey Mike!

I am so stuck on my Rev A power supply. I've read through all the power supply posts for the new build.

It's all assembled and the ohms are all reading fine, but when I power up, the DC voltage is extremely low.

Any ideas on what I am missing?

THANK YOU!!

 

[Echo North]

Hey Mike!

I am so stuck on my Rev A power supply. I've read through all the power supply posts for the new build.

It's all assembled and the ohms are all reading fine, but when I power up, the DC voltage is extremely low.

Any ideas on what I am missing?

THANK YOU!!

Few things:

1. Fuse is in?
2. All three L brackets have the PCB secured to the enclosure?
3. DMM set to DC?
4. Do you have <0 ohm of resistance between the transformer yellow lead pad and enclosure? (power off)
5. What are your +30VDC and -10VDC readings?

Mike

 

[Echo North]

Now, everything seems to be fine with my rev. A. But now, all of a sudden, my D starts to crap out. It has worked before, calibrated and fine. But now it just farts, when I feed a bass signal to it. There meter shows what I hear. Any troubleshooting tips?

Bad switches are rare.

If you're getting cutting in and cutting out I would suspect either some joints are unsoldered/cold soldered. You should reflow suspect joints.

Also all L brackets must be secure to the PCB chassis. They are part of the grounding system.

Mike

 

[stringmike]

Hi Mike
Checked the L brackets and any suspicious solderings. Still no luck.
It’s not that it pops in and out, more like a fuzz pedal with a very dying battery...

 

[Echo North]

Hi Mike
Checked the L brackets and any suspicious solderings. Still no luck.
It’s not that it pops in and out, more like a fuzz pedal with a very dying battery...

Is this the Rev D?

Set your compressor controls:

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

TP1
TP15
BRN Wire on Output

Then measure between + and - on the output XLR.

Mike

 

[frenkonio]

Hi guys, maybe it has been already written... I read on the BOM of the REV. D that C2 caps is 27pF and C13 is 270pF but in the bag there are only 2 blu caps (ceramic) with "271" written on. I also saw other two REV. D (that I still didn't assembled yet) and both ceramic caps bags have the same 2 "271" blu caps. What's wrong?

 

[Echo North]

Hi guys, maybe it has been already written... I read on the BOM of the REV. D that C2 caps is 27pF and C13 is 270pF but in the bag there are only 2 blu caps (ceramic) with "271" written on. I also saw other two REV. D (that I still didn't assembled yet) and both ceramic caps bags have the same 2 "271" blu caps. What's wrong?

Hmmm I'll have to look into it.  May be a kitting error on our side.

You can fill out a missing parts form on the site. 

Hairballaudio.com/missing

 

[Echo North]

Hmmm I'll have to look into it.  May be a kitting error on our side.

You can fill out a missing parts form on the site. 

Hairballaudio.com/missing

You should have a 10pF, 27pF, 2 x 220pF, and a 270pF correct?

What do you have?