[BUILD] FET/500 Official Support Thread

[Echo North]

Sounds tricky!!!! ;-)
Yes!!! I can test the unit outside the rack and check the top PCB... I've got an extension connector for my lunchbox.
It's the one proposed by "soundskulptor" a french company that make preamps like you.

I can check everything going IN and OUT the FET500 Rev A.

Once again, Thanks a lot for your help!!!
Have a nice Sunday

Antoine

For this testing, you need to use the ANODE (no line) of D4 as your ground reference (common).

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 - or PIN 8 and 10)

What is your ACV and each of the 3 output pot terminals?

Mike

 

[antoine00]

For this testing, you need to use the ANODE (no line) of D4 as your ground reference (common).

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 - or PIN 8 and 10)

What is your ACV and each of the 3 output pot terminals?

Mike

Thanks Mike!!!
I'll try that next week...

I'm just not sure about your settings :

Input: 12 O’Clock                      OK
Output: 12 O’Clock                OK
Attack: GR OFF                        ???? Attack Full CW???? like in the procedure for calibration
Release: Full CW                      OK
Ratio: 20:1                                  OK
Meter: GR                                    OK
Signal: Sine 1kHz @ 0dBu (0.775 VAC across input + and - or PIN 8 and 10)

Thanks a lot Mike!!!!!
Antoine

 

[Echo North]

Thanks Mike!!!
I'll try that next week...

I'm just not sure about your settings :

Input: 12 O’Clock                      OK
Output: 12 O’Clock                OK
Attack: GR OFF                        ???? Attack Full CW???? like in the procedure for calibration
Release: Full CW                      OK
Ratio: 20:1                                  OK
Meter: GR                                    OK
Signal: Sine 1kHz @ 0dBu (0.775 VAC across input + and - or PIN 8 and 10)

Thanks a lot Mike!!!!!
Antoine

Of sorry. That knob doesn't matter. Engage the GR OFF switch.

 

[antoine00]

Of sorry. That knob doesn't matter. Engage the GR OFF switch.

Hello Mike,

I've put 1khz @ 0Dbu (0,778 VAC direct from my Input XLR before connecting my FET 500 Rev A .

Here's what I got with the FET 500 connected :
- I've re-checked my Input with the FET 500 and found 0,626 VAC

- Between the anode of D4 and PIN 2 (OUT+) decreasing from 0,85 (when only  the com is at D4) to almost nothing
- Between the anode of D4 and PIN 3 (OUT- Lo)  0,850 VAC
- Between the anode of D4 and PIN 2 (OUT+) decreasing from 0,85 (when only  the com is at D4) to almost nothing

I've Re-Checked the Qbias like in the calibration procedure :
- nothing change with the Output between pin 2 and 4
- the LED are moving so I think nothings wrong with the meter PCB

Again... Thanks for your help Mike!!!!

 

[Echo North]

What is your DC V at the gate of Q1 as you rotate the Qbias? Use that D4 anode as your common.

https://www.soundtronics.co.uk/images/detailed/23/Ext-2300-298.jpg?t=1482942320

Mike

 

[antoine00]

What is your DC V at the gate of Q1 as you rotate the Qbias? Use that D4 anode as your common.

https://www.soundtronics.co.uk/images/detailed/23/Ext-2300-298.jpg?t=1482942320

Mike

I send 0,797VAC in the FET 500 with the 1kHz@0 Dbu (can't found 0,778 like yesterday...)

And found :

from 0 to 2,11 VDC between the gate of Q1 and the anode of D4 when I rotate the Qbias...

 

[Echo North]

I send 0,797VAC in the FET 500 with the 1kHz@0 Dbu (can't found 0,778 like yesterday...)

And found :

from 0 to 2,11 VDC between the gate of Q1 and the anode of D4 when I rotate the Qbias...

Do you mean -2.11 V DC?

 

[antoine00]

Do you mean -2.11 V DC?

Sorry!!!!

I found -2,11 V DC exactly

 

[Echo North]

Sorry!!!!

I found -2,11 V DC exactly

If you set it to -2.11 VDC does your unit pass signal?

Mike

 

[antoine00]

If you set it to -2.11 VDC does your unit pass signal?

Mike

Signal pass yes!!!!

and I'm so sorry It's not -2,11VDC but 2,11VDC...

I'll send you a good bottle of wine for being so helping!!!!

 

[Echo North]

Signal pass yes!!!!

and I'm so sorry It's not -2,11VDC but 2,11VDC...

Sorry, try measuring that using the ground pin on the edge card.

 

[antoine00]

Sorry, try measuring that using the ground pin on the edge card.

Between Pin 5 (com) and the gate of Q1 I found :

14,33 VDC  (not minus!!! I just double checked this time ) ;-)

 

[Echo North]

Between Pin 5 (com) and the gate of Q1 I found :

14,33 VDC  (not minus!!! I just double checked this time ) ;-)

Sorry, I had to go look at mine to confirm the grounding scheme again. 

What is your DC V at the meter PCB connector pin 3 (labeled -V out) using the Anode of D4 as your common point?

Mike

 

[antoine00]

Sorry, I had to go look at mine to confirm the grounding scheme again. 

What is your DC V at the meter PCB connector pin 3 (labeled -V out) using the Anode of D4 as your common point?

Mike

I found  between pin 3 (-V out) and D4
- 8,91 VDC

 

[Echo North]

I found  between pin 3 (-V out) and D4
- 8,91 VDC

Excellent. That's perfect.

Now try again at the gate of Q1.  What is your DC V between the gate and D4 as you rotate the QBias pot?

 

[antoine00]

Excellent. That's perfect.

Now try again at the gate of Q1.  What is your DC V between the gate and D4 as you rotate the QBias pot?

Same Value :

from 0 DC V  to -2,11 DC V

 

[Echo North]

Same Value :

from 0 DC V  to -2,11 DC V

Perfect. So that is correct.

Your output level should drop as you rotate from -2.11 to 0.  If it's not dropping, but you see your meter drop. My guess is that you don't have a wire link soldered into that OPTR-1 spot....OR Q1 is fried.

Mike

 

[antoine00]

Perfect. So that is correct.

Your output level should drop as you rotate from -2.11 to 0.  If it's not dropping, but you see your meter drop. My guess is that you don't have a wire link soldered into that OPTR-1 spot....OR Q1 is fried.

Mike

Thanks Mike,

My guess is that Q1 is fried... I'm sure about my wire link...

Is there something special about the 2N5457 ?!!!!

There is two of them at Mouser'shop... which one do I have to buy?!!!! the TO-92 or the TO-92-3...?!

I'll keep you in touch about It.

 

[antoine00]

Thanks Mike,

My guess is that Q1 is fried... I'm sure about my wire link...

Is there something special about the 2N5457 ?!!!!

There is two of them at Mouser'shop... which one do I have to buy?!!!! the TO-92 or the TO-92-3...?!

I'll keep you in touch about It.

Farnell have 3 references....
Which one is the good one?!!!!

Thanks Mike!!!! Have a good week end!!!!

 

[Echo North]

Farnell have 3 references....
Which one is the good one?!!!!

Thanks Mike!!!! Have a good week end!!!!

We can send you a new matched set if you like. Send us an email.

Mike