[BUILD] FET/500 Official Support Thread

[DonnieDarko]

Hey Mike,

Thank you for the quick help!

There go my measurements:

C1: 0.085
C7: 2.76
C8: 0.014
Output tx BRN: 2.784

Most of the meauring Points you named cause a huge humming when measuring.

The solder points under the output pot are extremely sensitive. When touching one of them, the humm/voltages go crazy.

 

[Echo North]

seems like something might be off with your output pot.

Is it solder well? Do those three pads look damaged?

 

[DonnieDarko]

I doublechecked, soldered it out, cleaned everything, soldered it in again. Measured it, seems fine and working.

Still very sensitive when touching stuff in in this section.

 

[DonnieDarko]

I meant the pot seems to work correctly - unit still doesn´t pass audio.

 

[Echo North]

Hard to say, maybe a bad pot, but that would be super weird. You could try a new one.

email us.

Mike

 

[Houroftower]

Hi,
While desoldering a resistor in R48, I unfortunately also removed the eyelet from the top (silkscreened) side of the pcb during removal.
The eyelet remains intact on the underside of the pcb.
I have checked for continuity between the intact eyelet on the underside and the next point on the pcb and it appears there is continuity.
What do you recommend for my next step? Can/should I just solder the resistor in, and then verify continuity again, or do I require a repair to the "top" side eyelet in R48 before I proceed?
Thanks.

 

[mnats]

Hi,
While desoldering a resistor in R48, I unfortunately also removed the eyelet from the top (silkscreened) side of the pcb during removal.
The eyelet remains intact on the underside of the pcb.
I have checked for continuity between the intact eyelet on the underside and the next point on the pcb and it appears there is continuity.
What do you recommend for my next step? Can/should I just solder the resistor in, and then verify continuity again, or do I require a repair to the "top" side eyelet in R48 before I proceed?
Thanks.

When you write "eyelet" I'll assume you mean "pad" meaning the annular ring of metal surrounding the hole that the component passes through. R48 is a different component for the A, D revs and the F, but in each case there is no top track that it connects to. So you should be OK.

 

[Houroftower]

Yes, I was referring to the annular metal ring/pad. It is a Rev D build.  Thanks for your assistance.

 

[sebperry]

Hi there,

I was about halfway through the calibration process for my FET 500 Rev D when I realized that I had a problem and would not be able to complete the process.

I noticed during the Q bias adjustment that I could not get up to 11DBU or 2.75 VAC. The highest I could really get was closer to 5 or 6 DBU. However, I completed the Q bias  adjustment anyway hoping the problem would sort itself out. Obviously, when it came time to calibrate the peak light I couldn't even get close to 16dbu. The problem seems to be in the output stage, though I suppose it could be anywhere?

I've double checked the soldiers and everything seems alright, any help would be much appreciated!!

seb

 

[mnats]

I was about halfway through the calibration process for my FET 500 Rev D when I realized that I had a problem and would not be able to complete the process.

I noticed during the Q bias adjustment that I could not get up to 11DBU or 2.75 VAC. The highest I could really get was closer to 5 or 6 DBU. However, I completed the Q bias  adjustment anyway hoping the problem would sort itself out. Obviously, when it came time to calibrate the peak light I couldn't even get close to 16dbu. The problem seems to be in the output stage, though I suppose it could be anywhere?

I've double checked the soldiers and everything seems alright, any help would be much appreciated!!

Of the things listed in the FAQ linked from the first post, what have you tried so far?

 

[sebperry]

mnats,

Good point, I will double check the resistor values and reflow questionable soldier points and see if that makes a difference.

Thanks

 

[Houroftower]

Hi,

I have completed my Rev D build and attempted to successfully calibrate a few times but I continue to run into the same problem.

I am using a DMM and a DAW to calibrate.

To date I have visually verified that all components are correct on both the meter board and the main pcb.
I have redone the solder joints that to my eye could have any issue.

But the problem continues at the same step of the calibration process everytime.
So I think I need some guidance on locating where I have either caused damage,  have a faulty component - or some other issue.

Here is my problem:

Calibration (in dot mode) goes well until the final step -- Gain Reduction Tracking.

I zero the meter, using the zero adjust trim pot to get the -1db light on. The red slam light is off at this point.

The problem essentially begins once I deactivate the GR Off switch.

Once I start raising the input level -- The lights, from top to bottom, including the red slam light become lit up, and stay lit (bar mode style I suppose) as I increase the input.  It is not behaving in dot mode anymore from this point on.
The unit passes audio but to my ear it sounds like attack, release and ratio knobs have little to no effect.
I will only add that all trim pots were zeroed prior to calibration, I have verified that I am calibrating in 20:1 mode and I do have a test jig.
Thanks in advance for your help. If I can describe the problem more clearly, or if a picture or video would help, let me know.

 

[mnats]

Once I start raising the input level -- The lights, from top to bottom, including the red slam light become lit up, and stay lit (bar mode style I suppose) as I increase the input.  It is not behaving in dot mode anymore from this point on.

Just so I understand correctly, both the top gain reduction meter and the lower audio level meters operate in dot mode exactly when? Because if GR Off is active then the top meter shouldn't change at all. You have no connections between the bar mode pins?

 

[Houroftower]

Hi,

Both meters should be in dot mode, there is nothing connecting the bar mode pins.
Until the final calibration step both do appear to be functioning properly in dot mode.

I'm good up until this point: https://youtu.be/xIbD-NCo-v4?t=812

Then when I get to this point: https://youtu.be/xIbD-NCo-v4?t=872

...I increase the input level -- and instead of seeing  individual led's lighting up one by one on the top meter they begin to light up in a bar from red to green to yellow. They stay lit as the input level increases. When I decrease the input level this bar recedes until there is just the "0" green led lit as it was in the first youtube link and the red slam light is off. The bottom meter stays in dot mode.

So if I were to continue on to the NEXT step where we do Tracking Adjust and get the yellow -9 led lit...I would have a bar of lights all the way up to the top red slam led instead of the single -9 led lit.

 

[Echo North]

Hi,

Both meters should be in dot mode, there is nothing connecting the bar mode pins.
Until the final calibration step both do appear to be functioning properly in dot mode.

I'm good up until this point: https://youtu.be/xIbD-NCo-v4?t=812

Then when I get to this point: https://youtu.be/xIbD-NCo-v4?t=872

...I increase the input level -- and instead of seeing  individual led's lighting up one by one on the top meter they begin to light up in a bar from red to green to yellow. They stay lit as the input level increases. When I decrease the input level this bar recedes until there is just the "0" green led lit as it was in the first youtube link and the red slam light is off. The bottom meter stays in dot mode.

So if I were to continue on to the NEXT step where we do Tracking Adjust and get the yellow -9 led lit...I would have a bar of lights all the way up to the top red slam led instead of the single -9 led lit.

Hmmmm.  You;ve gone through all of the meter parts for value, orientation, and solder? 

 

[Houroftower]

Yes I have.

 

[Echo North]

Can you post a video of the issue?  I just can't really visualize it.

 

[Houroftower]

No problem. I'll post something to Youtube and PM you the link.

 

[Echo North]

No problem. I'll post something to Youtube and PM you the link.

Email me the link "info (at) hairballaudio (dot) com"

 

[mnats]

...I increase the input level -- and instead of seeing  individual led's lighting up one by one on the top meter they begin to light up in a bar from red to green to yellow. They stay lit as the input level increases. When I decrease the input level this bar recedes until there is just the "0" green led lit as it was in the first youtube link and the red slam light is off. The bottom meter stays in dot mode.

The more accurate your fault descriptions are, the better advice you'll receive. Previously you wrote "Once I start raising the input level -- The lights, from top to bottom, including the red slam light become lit up, and stay lit..." Now you've written that the bottom meter stays in dot mode. My question is what happens to the red slam light? That is part of the output level metering on the bottom.

The Gain Reduction meter on the top simply measures the DC voltage coming from the main PCB. The GR Off switch allows a portion of the audio signal to reach the GR Control Amp when inactive. So it would be interesting to know what signal the meter board is receiving. Put an oscilloscope probe on pin one of CN200, the board to board connector. Show us what the signal looks like.