[BUILD] FET/500 Official Support Thread

[Echo North]

Email Question:

Hi,
I finally plugged in my two fet/500's rev D
One is working very well except for the metering. I can't seem to calibrate the VU or the peak.
The peak and vu are way to high when set to the output level specified.
The GR seems about right. It sounds great. Should the slam led turn on in slam mode? It doesn't at the moment
My other unit passes audio but doesn't compress at all, the is no difference with GR on or off even with the input cranked.

Slam works like the original.  The unit will peg hard right so the top red button will light and the meter will show GR erratically just like the original.

Often the trimmers can be set way off.  Turn the 0 adjust and GR trimmer till you hear a slight "click" that is the end of the trimmer.  They are 20 turn trimmers so rotate them each back the other way 10 turns and they will be centered.  Now try to calibrate starting with zero adjust.  As you make the adjustment go back and forth make small adjustments.  If that doesn't work, you need to check the metering sections for errors.

For the non compressing one, did the qbias adjustment go well?

Mike

Thanks for that, On my first unit the lowest I can go to get the peak to turn off is 1.2V , at 4.88v (16dbu) it never goes off
Likewise when I set the output at 0.388v I can only adjust between the 2dn and 3rd yellow led
I set the 20turn trimmers to halfway. The sound is good but the metering is way off

On the other Unit I get compression only with the 20:1 ratio and the GR OFF switch doesn't do anything. I am able to the Qbias and 0.388v output the first green led lights up but I can't adjust to the 2nd. The sound is quickly distorted when I turn up the input. Also the GR leds stay on in bypass/ GRoff .
Any ideas welcome

Have you tried swapping meter boards?  Did that fix the one that just has the metering issue?

Mike

 

[spaceboss]

So,  question:

Is the red led (which indicates gain reduction in/out necessary?

I literally had a cat jump up on my bench. In knocking the bugger off so that he wouldn't experience the warmth of my Hako iron, I pushed the circuit board away. There was no collateral damage except the red led snapped off and took the surface mount pads with it. 

I can live without a gain reduction LED, but if it is needed to complete a circuit, I'd wire one up to board at the proper connection points.

The good news is, if this is the one small issue I have per project, I've already got it out of the way.

Thanks!

 

[Echo North]

So,  question:

Is the red led (which indicates gain reduction in/out necessary?

I literally had a cat jump up on my bench. In knocking the bugger off so that he wouldn't experience the warmth of my Hako iron, I pushed the circuit board away. There was no collateral damage except the red led snapped off and took the surface mount pads with it. 

I can live without a gain reduction LED, but if it is needed to complete a circuit, I'd wire one up to board at the proper connection points.

The good news is, if this is the one small issue I have per project, I've already got it out of the way.

Thanks!

No not necessary.  You could hot wire one on by following the trace to the next connectable point.

Mike

 

[LHS]

accidentally posted this in the regular 1176 thread-

I accidentally switched the 100pf nichicon caps with the united chemi con caps on C2500 and C2600 (rev a 500 kit).

I don't have a desoldering gun and my experiences have not been great with removing previously soldered components. How critical is

 

[Echo North]

accidentally posted this in the regular 1176 thread-

I accidentally switched the 100pf nichicon caps with the united chemi con caps on C2500 and C2600 (rev a 500 kit).

I don't have a desoldering gun and my experiences have not been great with removing previously soldered components. How critical is

I think you mean 100uF.  The Chemi-Cons are fine if you have the polarity right but I would switch them.  We can send new ones if needed.

 

[gunner666]

Hi everyone,

  Thanks in advance for the help.  My Rev D was working great for a few months.  Today when I went to use it I had an issue.  Bypassed it's fine.  When it's not bypassed there is only a very faint signal at the output, mostly high end.  The gain reduction meter never moves regardless of input level or ratio.  The output meter gets as high as -10 with everything cranked but oddly enough the peak LED comes on.

  Here's where I am in troubleshooting.  I assume because audio comes through when it's bypassed I can rule out any external cable, rack, patch bay issues.  Because the problem remains when the GR off LED is on I assume the problem must be outside of the gain reduction circuit.  I've looked at the schematic but it's not as simple as my VP26's. 

  If anyone has any advice on where to start I'd greatly appreciate it! I have a scope, tone generator and a 500 extension cable.

Thanks!

-mike

 

[mnats]

As suggested in the Troubleshooting FAQ linked from the first post this is a good place to use a signal tracer. It's worth building a 500 jig if you don't have one already so the module is easily accessible from all sides (you'll mostly want the 'bottom' of the main PCB).

Work in blocks by feeding it a known signal, see if it gets through the input attenuator and transformer, then to the output pot, then through the line amp. Given that it was working and now isn't you may be chasing poor solder joints but keep your mind open and figure out where the signal gets messed up. Your problem will be before that point.

Hi everyone,

  Thanks in advance for the help.  My Rev D was working great for a few months.  Today when I went to use it I had an issue.  Bypassed it's fine.  When it's not bypassed there is only a very faint signal at the output, mostly high end.  The gain reduction meter never moves regardless of input level or ratio.  The output meter gets as high as -10 with everything cranked but oddly enough the peak LED comes on.

  Here's where I am in troubleshooting.  I assume because audio comes through when it's bypassed I can rule out any external cable, rack, patch bay issues.  Because the problem remains when the GR off LED is on I assume the problem must be outside of the gain reduction circuit.  I've looked at the schematic but it's not as simple as my VP26's. 

  If anyone has any advice on where to start I'd greatly appreciate it! I have a scope, tone generator and a 500 extension cable.

Thanks!

-mike

 

[LHS]

I was re-soldering the red bypass led and inadvertently lifted the solder pad. I can live with the light not working but will this affect the functionality of unit? Any suggestions for a fix?

 

[Echo North]

I was re-soldering the red bypass led and inadvertently lifted the solder pad. I can live with the light not working but will this affect the functionality of unit? Any suggestions for a fix?

No it's fine.

You can trace the lifted pad to the next solder pad and connect the LED there or try and scrape away some solder mask on the pad trace and solder there.

Mike

 

[Echo North]

Moving an e-mail discussion to the support thread.

Basic issue: QBias sets but user can't pass the GR meter calibration. Unit is not compressing.

Instructions to user: If you have little mini grabber leads you can attach them, insert the module and test. The black/common lead always is attached to ground.  You can get ground at D4 on the lead without the line. Check pad 21 voltages. To do that connect the red lead to the point where R52 and R53 connect. So you can clip your lead to one of those resistor leads on the side where they are connected. Check the traces to confirm or use your DMM in Ω.  Now plug it in and power up and test your DC V at that point at 4:1 and 20:1. Should be a negative DC voltage with 4 being small and 20 being big. Now check your AC V where R49 connects to the + side of C19..  Same thing 4 and 20. same thing 4 should be less than 20.

User report:

Pad 21 - R52/R53
20:1 -5.496 DC V
4:1 -1.669 DC

R49/C19
20:1 -  0.274 AC V
4:1 - 0.274 AC V

Pad 21 voltages look ok.  The second AC readings do not. 4:1 should be double that and 20:1 should be 3V AC ish. But I may have had the setting wrong....

--------------------------------------

No try this.  Set your input/output mid way, GR ON (fully CW) and release fully CW.  Connect your probe at pad 22. Best way to get this would be at a leg of R36 and R37 where they connect to each other. Measure your AC V at 20:1 and 4:1.

Under the same conditions, measure your AC V at R49/C19 at 20:1 and 4:1 again.

Mike

 

[Santos76]

I just completed my FET 500 REV A and without any input, the unit is outputing a staccato noise. Sort of like choppy white noise. Rhythmic though...it is in perfect time with itself.

When i sweep the attack knob it acts almost like a filter getting to its brightest when it's wide open. The upper portion of LED's continually light up from bottom to top in time with the noise.

Any idea as to where I could have gone wrong? I am overwhelmed as to where I should start the troubleshooting process.

FET/500 page, linked searchable documentation
Calibration video added!
General troubleshooting page
Sub-site for boards and kits

Please post support questions not covered in the documentation linked above to this thread.

As data is collected I will either update the page(s) linked above or link to the forum posts that cover common build issues or questions from the first or second posts of this thread.

Please keep any commercial discussion or general comments in the White Market thread. Thank you.

 

[Echo North]

I just completed my FET 500 REV A and without any input, the unit is outputing a staccato noise. Sort of like choppy white noise. Rhythmic though...it is in perfect time with itself.

When i sweep the attack knob it acts almost like a filter getting to its brightest when it's wide open. The upper portion of LED's continually light up from bottom to top in time with the noise.

Any idea as to where I could have gone wrong? I am overwhelmed as to where I should start the troubleshooting process.

FET/500 page, linked searchable documentation
Calibration video added!
General troubleshooting page
Sub-site for boards and kits

Please post support questions not covered in the documentation linked above to this thread.

As data is collected I will either update the page(s) linked above or link to the forum posts that cover common build issues or questions from the first or second posts of this thread.

Please keep any commercial discussion or general comments in the White Market thread. Thank you.

Unfortunately that could be anything. I'm really stuck as to even suggest where to start. Never heard of that issue and that is VERY general.

If I had to suggest something I'd suggest this in order:

1. Consider just paying the $100 and having us repair it if you're that overwhelmed and not sure where to start.
2. If you're looking for issues...does it work in bypass mode?
3. Keep it in GR OFF mode and look at the top half the schematic. Check all of the components on your PCB and make sure they are the correct value and soldered well.

Mike

 

[Santos76]

Thanks Mike,

I want to stubbornly get to the bottom of it myself esp. since I am in Canada and our dollar is so s**t that the repair would cost much more than it would in the states. In all likelihood it is something to do with an early step. Although I had built some CAPI stuff, the build was much simpler on those so my work really improved on this kit...like the resistors on the main board looked like they were done by someone else by the time I got to the meter board! I will go back to the earl stuff and let you know what I find.

Chris

 

[Echo North]

Thanks Mike,

I want to stubbornly get to the bottom of it myself esp. since I am in Canada and our dollar is so s**t that the repair would cost much more than it would in the states. In all likelihood it is something to do with an early step. Although I had built some CAPI stuff, the build was much simpler on those so my work really improved on this kit...like the resistors on the main board looked like they were done by someone else by the time I got to the meter board! I will go back to the earl stuff and let you know what I find.

Chris

Ya I would go through the whole build carefully. Clean it up and confirm values.

Mike

 

[junomat]

Hey!

First off, thanks so much for what you do.

I just finished building the FET/500 Rev D. I did the calibration and everything is sounding great, but I can't seem to get the orange LED to light up... If soldered and re-soldered...

Can an LED be bad? Any suggestions on fixing this??

 

[Echo North]

Hey!

First off, thanks so much for what you do.

I just finished building the FET/500 Rev D. I did the calibration and everything is sounding great, but I can't seem to get the orange LED to light up... If soldered and re-soldered...

Can an LED be bad? Any suggestions on fixing this??

You could test the LED with a DMM (check google for methods), see if it's dead.

LED's (and all semi-conduuctors) are sensitive to static electricity and heat when installing. Also, see if either pad is lifted.

Mike

 

[junkface]

hey mike, et al,
was having a problem with my fet 500 (rev F). built and calibrated it up and it was working fine for the few days I first used it. came back from a trip and now it's not passing signal anymore unless it's in bypass. decided to double check all the soldering and in the process mucked up a solder pad for the input xfo. according to the data sheet though, pin 2 (also 3,7) is not connected, which looks in line with the schematic. am I correct that I can just disreguard pin 2 or do I need to jumper it somewhere?
if that's not the issue then I'm waiting for a 500 jig to arrive so i can start signal tracing...

 

[Echo North]

hey mike, et al,
was having a problem with my fet 500 (rev F). built and calibrated it up and it was working fine for the few days I first used it. came back from a trip and now it's not passing signal anymore unless it's in bypass. decided to double check all the soldering and in the process mucked up a solder pad for the input xfo. according to the data sheet though, pin 2 (also 3,7) is not connected, which looks in line with the schematic. am I correct that I can just disreguard pin 2 or do I need to jumper it somewhere?
if that's not the issue then I'm waiting for a 500 jig to arrive so i can start signal tracing...

Bummer.

Ya pin 2 is not connected. Let us know what you find in the signal trace.

Mike

 

[junkface]

hey mike, et al,
was having a problem with my fet 500 (rev F). built and calibrated it up and it was working fine for the few days I first used it. came back from a trip and now it's not passing signal anymore unless it's in bypass. decided to double check all the soldering and in the process mucked up a solder pad for the input xfo. according to the data sheet though, pin 2 (also 3,7) is not connected, which looks in line with the schematic. am I correct that I can just disreguard pin 2 or do I need to jumper it somewhere?
if that's not the issue then I'm waiting for a 500 jig to arrive so i can start signal tracing...

Bummer.

Ya pin 2 is not connected. Let us know what you find in the signal trace.

Mike

thx. will do

 

[junomat]

Hey!

First off, thanks so much for what you do.

I just finished building the FET/500 Rev D. I did the calibration and everything is sounding great, but I can't seem to get the orange LED to light up... If soldered and re-soldered...

Can an LED be bad? Any suggestions on fixing this??

You could test the LED with a DMM (check google for methods), see if it's dead.

LED's (and all semi-conduuctors) are sensitive to static electricity and heat when installing. Also, see if either pad is lifted.

Mike

Thanks for responding. It seems like it is fried. How do I purchase a replacement?

And a follow up question.

The attack and release knobs feel much more lose compared to the other pots... Is there a better way to secure them better?