[BUILD] FET/500 Official Support Thread

[Echo North]

Ok...I turned counter clockwise til I heard a click. Then turn ten times clock wise. Nothing yet, so far. What’s the next step?

Both the zero adjust and tracking pots....then try and re-calbrate.

 

[eMIX305]

So, will re adjusting the tracking pots disturb the output meter calibration I’ve already set? Or is this what I’m trying to do because I’ve calibrated output at a level that the GR meter isn’t reading?

 

[eMIX305]

I centered all tracking pots, recalibrated q bias, peak led @ 4.88 v & vu -6  @ .388 v. Everything went smooth.
Still no response on GR meter. I will quadruple check the led solder points, but everything looks good. I did notice that when I was calibrating the output via, I didn’t have to adjust the second turn pot, and even when I did turn it, there was no affect on the led read out at all. Not sure if this is a clue to the problem. Let me know if there is anything I can specifically do to narrow it down. Thanks.

 

[Echo North]

I centered all tracking pots, recalibrated q bias, peak led @ 4.88 v & vu -6  @ .388 v. Everything went smooth.
Still no response on GR meter. I will quadruple check the led solder points, but everything looks good. I did notice that when I was calibrating the output via, I didn’t have to adjust the second turn pot, and even when I did turn it, there was no affect on the led read out at all. Not sure if this is a clue to the problem. Let me know if there is anything I can specifically do to narrow it down. Thanks.

Sorry could you clarify a little more?  Not sure what the second pot is.

 

[eMIX305]

The second pot I’m referring to is the second turn pot that referenced in the vu calibration sequence. The one used to make sure the vu is reading at -10 (second led on the output meter).

 

[Echo North]

The second pot I’m referring to is the second turn pot that referenced in the vu calibration sequence. The one used to make sure the vu is reading at -10 (second led on the output meter).

Are you still not seeing any illuminated LEDs in the GR Meter in either bypass or compression enabled?

Mike

 

[eMIX305]

Correct. At this point, there is still no led response on the GR meter in either mode.

 

[WillDuc]

Hi Mike, I just thought i would report back concerning my problem with the VU meter. After inspection of both boards i found out i had swapped one of the two voltage regulator (lm317LZ) for the 2n5088 transistor. Unsoldering both of them was one hell of a job but it's working fine now!

Thanks for your time,
William

 

[Echo North]

Correct. At this point, there is still no led response on the GR meter in either mode.

You'll want to triple check all of the components on the board, look for bad joints and check the parts around the IC on the main PCB.  Make sure values are not swapped.

Mike

 

[Echo North]

Hi Mike, I just thought i would report back concerning my problem with the VU meter. After inspection of both boards i found out i had swapped one of the two voltage regulator (lm317LZ) for the 2n5088 transistor. Unsoldering both of them was one hell of a job but it's working fine now!

Thanks for your time,
William

Nice!

 

[Echo North]

Moved from Rev D Rack thread:

Hello all, I completed the build of the 500 series FET/D, but when powered on the gain reduction LEDs are pulsing (with pulse rate controlled by the release potentiometer) and when passing audio through the device, the audio clicks at the rate of the LED pulsing. Last night I was able to investigate with a tech and we discovered that the negative supply pulses when the gain reduction knob is out. When pushed in, we do not see pulsing [which is the reverse of #4 of the FAQ for common issues with this device]. We are not sure why this may be happening and are wondering if anyone may have any advice on the issue?
Many thanks in advance

Are all of the DIP 8 chips installed the the correct place and oriented correctly?

 

[warmtape]

Moved from Rev D Rack thread:

Are all of the DIP 8 chips installed the the correct place and oriented correctly?

Yes, confirmed that they are all placed correctly (attaching a PDF of 4 images of front/back of both PCBs).
This was my first build, so it's messy and I'm wondering if flux residue could cause this type of issue?
However, we are seeing a small pulsing on diode 4, which seems to correspond to the rate of the LED/GR pulsing.

 

[Echo North]

Yes, confirmed that they are all placed correctly (attaching a PDF of 4 images of front/back of both PCBs).
This was my first build, so it's messy and I'm wondering if flux residue could cause this type of issue?
However, we are seeing a small pulsing on diode 4, which seems to correspond to the rate of the LED/GR pulsing.

Diode 4 on the main PCB?

Are you sure those Q's on the meter PCB are in the right spot.  There are 2 regulators (LM317) and one transistor (5088).

You should clean off flux, but I doubt that is causing your power issue.

Repair if interested:
https://www.hairballaudio.com/build-support-services

Mike

 

[ubermetal]

Greetings,

A few months ago I built a Rev A. It came together and calibrated easily. I've used it on vocals constantly since I got it, and now I'm addicted to it and don't want to record without it. This past weekend, after perhaps 40 hours of use over the space of several months, a little distortion started creeping in. This was okay at first, as it worked with the style of vocal I was recording. But it kept getting worse, and now the level of distortion makes my Rev A unusable.  It's not present when the unit is bypassed. Where should I start looking?

Thanks in advance!

Josh

 

[Echo North]

Greetings,

A few months ago I built a Rev A. It came together and calibrated easily. I've used it on vocals constantly since I got it, and now I'm addicted to it and don't want to record without it. This past weekend, after perhaps 40 hours of use over the space of several months, a little distortion started creeping in. This was okay at first, as it worked with the style of vocal I was recording. But it kept getting worse, and now the level of distortion makes my Rev A unusable.  It's not present when the unit is bypassed. Where should I start looking?

Thanks in advance!

Josh

Hmmmm weird one.  Hard to say without probing around which is near impossible without a jig.  Does Q6 have a heatsink on it? Are any resistors around Q6 burning?

Could start by trying a new Q6.

Mike

 

[ubermetal]

Q6 does have a heat sink on it. The unit does seem to be running hot, though. I'll feel around for hot parts and probably replace Q6.

Thanks Mike!

Hmmmm weird one.  Hard to say without probing around which is near impossible without a jig.  Does Q6 have a heatsink on it? Are any resistors around Q6 burning?

Could start by trying a new Q6.

Mike

 

[Echo North]

Q6 does have a heat sink on it. The unit does seem to be running hot, though. I'll feel around for hot parts and probably replace Q6.

Thanks Mike!

Q6 should get hot...but over time it can get too hot.

 

[ubermetal]

Hence the heat sink. Got it. Do you think it would help to put a fan on it?

Q6 should get hot...but over time it can get too hot.

 

[Echo North]

Hence the heat sink. Got it. Do you think it would help to put a fan on it?

No it shouldn't fail with the supplied sink.  More likely a bad part.  If it's even Q6.

Mike

 

[warmtape]

Diode 4 on the main PCB?

Are you sure those Q's on the meter PCB are in the right spot.  There are 2 regulators (LM317) and one transistor (5088).

You should clean off flux, but I doubt that is causing your power issue.

Repair if interested:
https://www.hairballaudio.com/build-support-services

Mike

Hi Mike, yes, I saw pulsing on diode 4 of the main pcb. I've also triple checked that the Qs on the meter PCB and that the 2 regulators and one transistor are correctly placed.
I will try to probe the board again but please let me know if pulsing on diode 4 is strange and if you have any idea about that.
Thanks