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

Echo North · Jul 2, 2018

wmjohnson said:
No, not when i rotate the release.

Only by switching ratios. At 20:1 it's sitting at -6.6vdc.

That's good.

You should pull and test CR2/3 next.

wmjohnson · Jul 2, 2018

wmjohnson said:
No, not when i rotate the release.

Only by switching ratios. At 20:1 it's sitting at -6.6vdc.

strange update: just finished putting a rev F (red stripe, for searchability) together and its behaving identically. it works as expected at the shortest release time, as soon as i rotate it ccw the meter shoots left and it compresses. so, at the very least it it must be something i messed up on both of them.

Echo North · Jul 2, 2018

wmjohnson said:
strange update: just finished putting a rev F (red stripe, for searchability) together and its behaving identically. it works as expected at the shortest release time, as soon as i rotate it ccw the meter shoots left and it compresses. so, at the very least it it must be something i messed up on both of them.

So to be clear the meter is moving (more than a 1/4 dB) with no signal as you rotate the release?

Mike

wmjohnson · Jul 2, 2018

Hairball Audio said:
So to be clear the meter is moving (more than a 1/4 dB) with no signal as you rotate the release?

Mike

Yes, on both units it goes all the way left and tp7 rises almost to ground.

Echo North · Jul 2, 2018

wmjohnson said:
Yes, on both units it goes all the way left and tp7 rises almost to ground.

Ya I'm stumped. Check the polarity on those tantalums and those FDH33 diodes.

You might consider sending one in for repair.

Mike

wmjohnson · Jul 2, 2018

Hairball Audio said:
Ya I'm stumped. Check the polarity on those tantalums and those FDH33 diodes.

You might consider sending one in for repair.

Mike

Dang. I pulled one of the diodes and it measues open one way, and ~3meg the other way. does this sound right?

Will

Echo North · Jul 2, 2018

wmjohnson said:
Dang. I pulled one of the diodes and it measues open one way, and ~3meg the other way. does this sound right?

Will

You should confirm with the diode test function, but that doesn't sound good. Diodes are very easily damaged by static electricity (handling) and high heat when soldering.

http://en-us.fluke.com/training/training-library/test-tools/digital-multimeters/how-to-test-diodes-using-a-digital-multimeter.html

wmjohnson · Jul 2, 2018

Hairball Audio said:
You should confirm with the diode test function, but that doesn't sound good. Diodes are very easily damaged by static electricity (handling) and high heat when soldering.

http://en-us.fluke.com/training/training-library/test-tools/digital-multimeters/how-to-test-diodes-using-a-digital-multimeter.html

Going by the diode function, it's dead. Do ya'll have them in your store? I can't find them.

Will

Echo North · Jul 2, 2018

wmjohnson said:
Going by the diode function, it's dead. Do ya'll have them in your store? I can't find them.

Will

Fill out a missing parts form. We'll send you some.

hairballaudio.com/missing

wmjohnson · Jul 2, 2018

Hairball Audio said:
Fill out a missing parts form. We'll send you some.

hairballaudio.com/missing

Right on, thanks.

stringmike · Jul 4, 2018

Hi Mike. I’m still troubleshooting here... I checked all the connectors, and I tried disconnecting CN9 to CN8, and it still passed the same, fuzzy signal with the cable disconnected. Does that give you any idea of what could be wrong?

stringmike said:
Hi Mike.
Here’s what I measured:
TP1: 0.122V
TP15: 2.10V
Brown wire: 6.25V
Output xlr: 6.22V

Sinkia · Jul 6, 2018

Hairball Audio said:
It's a combination of the Rev A being REALLY hot by design, the natural analog meter overshoot, and the original t-pad being very hard (impossible) to mimic.

You can lower the amount of signal you send to it, or in about 1 week we are going to be posting a mod to also adjust that issue. Basically you increase the value of R78, R19, R20, R21 to lower the amount of signal entering the side chain. Increase them all by about 5-10 x their current value to your taste.

Mike

Hi !

Coming back on this Topic after a few month of romance with my rev A.
I think its time now for switching those resistor !
Is anyone have test it? Is it working fine ?

While I'm here, I do have an issue with the vu meter calibration !
I have follow the step at least 3 or 4 times, and it's still the same..

At 0, my vu meter shows =1.5dB

CF pictures attached

Do you think I could just turn the front knopb with a small screwdriver? or it's something else? I'm leaving very well with it, but I'd like to have it "fixed"

Many thanks in advance
Best
Adrien

Echo North · Jul 9, 2018

stringmike said:
Hi Mike. I’m still troubleshooting here... I checked all the connectors, and I tried disconnecting CN9 to CN8, and it still passed the same, fuzzy signal with the cable disconnected. Does that give you any idea of what could be wrong?

What's the issue? The signal is fuzzy?

Is the unit compressing?

Echo North · Jul 9, 2018

Sinkia said:
Hi !

Coming back on this Topic after a few month of romance with my rev A.
I think its time now for switching those resistor !
Is anyone have test it? Is it working fine ?

While I'm here, I do have an issue with the vu meter calibration !
I have follow the step at least 3 or 4 times, and it's still the same..

At 0, my vu meter shows =1.5dB

CF pictures attached

Do you think I could just turn the front knopb with a small screwdriver? or it's something else? I'm leaving very well with it, but I'd like to have it "fixed"

Many thanks in advance
Best
Adrien

Just use the front zero adjust to zero your meter if it's been calibrated and drifts.

saqeef · Jul 16, 2018

Hairball Audio said:
Are you sure you are measuring the supply test points correctly? Measuring for DC V and using the chassis as your common? Also make sure that your PCB is mounted to the chassis with ALL 3 L brackets.

Mike

Thanks for your patience with me, Mike.

I double-checked the brackets just now, and the PCB is indeed mounted to the chassis with all 3 L brackets. I'm measuring for DC V using the chassis as my common, as you stated, and the cathode gives a bum reading. It might read something pretty miniscule for a brief moment, and then the reading descends to 0.

Echo North · Jul 17, 2018

saqeef said:
Thanks for your patience with me, Mike.

I double-checked the brackets just now, and the PCB is indeed mounted to the chassis with all 3 L brackets. I'm measuring for DC V using the chassis as my common, as you stated, and the cathode gives a bum reading. It might read something pretty miniscule for a brief moment, and then the reading descends to 0.

With the unit OFF, what is your DC resistance (Ω) between the chassis and the center power connector at the main PCB (yellow wire)?

Mike

saqeef · Jul 19, 2018

Hairball Audio said:
With the unit OFF, what is your DC resistance (Ω) between the chassis and the center power connector at the main PCB (yellow wire)?

Mike

The reading I get between those two points is about 0.2-0.3 ohms.

Echo North · Jul 19, 2018

saqeef said:
The reading I get between those two points is about 0.2-0.3 ohms.

What is your AC V reading at each orange wire of the transformer VS chassis ground?

Power on.

saqeef · Jul 19, 2018

Hairball Audio said:
What is your AC V reading at each orange wire of the transformer VS chassis ground?

Power on.

One wire read 16.16V AC, the other reads 15.72V AC.

Echo North · Jul 19, 2018

saqeef said:
One wire read 16.16V AC, the other reads 15.72V AC.

Do you have the voltage select switch set correctly?

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