[BUILD] CAPI FC526~500 Series~FET Limiter Kit~Official Support Thread

[Thekahn]

Man I'm such a noob!  :-[
Thanks Jeff.

When I input a 24.4 mV  (as close as I could get to 24.3 mV) signal i'm getting:
TP 1: 5.7 mV AC
Tp 2: 108.4 mV AC
TP 3: .906 V AC
Output: 1.808 V AC

It does look a tiny bit lower than the numbers in your test guide, but do you think it's close enough?


You should have the following:
TP1 = -42.4dBu or appx 5.8mV AC
TP2 = -16.3dBu or appx 117.7mV AC
TP3 = +1.73dBu or appx 939mV AC
Module’s Output = +7.75dBu

Hi Jeff, not sure if you saw my post (quoted above), but could you please respond when you have a chance?
Much appreciated,
Chris

 

[jsteiger]

Hi Jeff, not sure if you saw my post (quoted above), but could you please respond when you have a chance?
Much appreciated,
Chris

These look pretty OK to me. Might just be a DMM accuracy thing.

 

[fnhscar17s]

Hello all,

I have completed a 526 build. I am using the collective cases psu.

Everything looks decent measurement wise I was just wondering about my output level.

Tp1 12.6mv rms
Tp2 246 mv rms
Tp2 1.97 v rms

All measurements taken with a rigol oscilloscope with a 50 ohm feed through termination Bnc (my signal generator is 50 ohm output).

Output 10dbu at 2.44 v rms

I feel like the output is not quite as high as it should be as stated in the test points document. Do you guys have any ideas or is this suitable to move forward?

 

[fnhscar17s]

Any insights?

Am I good to go level wise. Output is basically about 4dbu short

 

[jsteiger]

Any insights?

Am I good to go level wise. Output is basically about 4dbu short

Sorry I have been crazy busy. I assume the 2nd TP2 in your post is actually TP3? If so, that is just before the transformer. If that is what it should be and the output is truly low, I would dbl check the transformer wiring. Also, not sure how you are measuring the output but at that point remember the balanced lines are floating with no reference to ground. If using a meter, do not check each phase to ground. Only measure between the +/-.

 

[fnhscar17s]

Thanks for the response. I am measuring across the positive and negative leads on the output via a feed thru terminated oscilloscope. My signal generator is 50 ohm outputting to the positive and negative leads for the input. Yes my 2nd tp2 is tp3 my bad that was a typo.

I am using a litz transformer and it was wired according to your pinout specified on your site I figured it could be the tx which I double checked it I'll make sure again to be sure. I also reflowed all of my solder joints on the board and no change.

Thanks Jeff you are always very helpful

 

[Thekahn]

Hi Jeff,
I was checking the DC voltage at point 11, and it was reading around 2.5V, but then I accidentally bridged a connection or two by accident with my DMM probe and now my voltage is down to 0.136volts DC,
any idea how I can pinpoint what happened?

here is how it's reading:

11=0.136V
10=0.134V                                                                 
9=0.132V
8= 0.130V
7=0.129V
6=0.127V
5=0.126V
4=0.125V
3=0.124V
2=0.120V
1=0.094V

 

[fnhscar17s]

So checked the 2623 output tx. I am using the litz version tx

Wired as follows:
Red on board wired to black on tx
Orange on board wired to red on tx
Blue on board wired to gray on the tx
Green on board wired to pink on tx
Brown on board wired to violet on tx
Black on board wired to orange on tx


Pulled the tx out to measure resistance:
Tx primary measures 16 ohms between red and black on two dmm including a third I threw in the mix.

The secondaries:
Violet and orange- 352 ohms on one multimeter and 305 on another
Pink and gray- 300 on one dmm 348 on another

Note the primary at 16 ohms was across the board on 3 different dmm

All dmm have 1meg input impedance I am pretty sure. Two fluke 8060a and one sperry dm6400

A had a hunch about the tx since all my other levels are good. But not too sure what to make of the readings here. I guess that would mess with the ratio of the winding I imagine? Or am I completely off here?

 

[jsteiger]

Hi Jeff,
I was checking the DC voltage at point 11, and it was reading around 2.5V, but then I accidentally bridged a connection or two by accident with my DMM probe and now my voltage is down to 0.136volts DC,
any idea how I can pinpoint what happened?

here is how it's reading:

11=0.136V
10=0.134V                                                                 
9=0.132V
8= 0.130V
7=0.129V
6=0.127V
5=0.126V
4=0.125V
3=0.124V
2=0.120V
1=0.094V

Maybe you fried the 2.5V shunt reference? You should have around 15.5V at the top of R12 (closest to the meter board edge) and 2.5V at the other end of it. If you have the 15.5V and NOT the 2.5V, I would bet you smoked the 2.5V shunt reference.

 

[jsteiger]

So checked the 2623 output tx. I am using the litz version tx

Wired as follows:
Red on board wired to black on tx
Orange on board wired to red on tx
Blue on board wired to gray on the tx
Green on board wired to pink on tx
Brown on board wired to violet on tx
Black on board wired to orange on tx


Pulled the tx out to measure resistance:
Tx primary measures 16 ohms between red and black on two dmm including a third I threw in the mix.

The secondaries:
Violet and orange- 352 ohms on one multimeter and 305 on another
Pink and gray- 300 on one dmm 348 on another

Note the primary at 16 ohms was across the board on 3 different dmm

All dmm have 1meg input impedance I am pretty sure. Two fluke 8060a and one sperry dm6400

A had a hunch about the tx since all my other levels are good. But not too sure what to make of the readings here. I guess that would mess with the ratio of the winding I imagine? Or am I completely off here?

For the Litz 2623-1 you should have the following:
Black to Red, 15.7Ω
Pink to Gray, 31.5Ω
Violet to Orange 31.5Ω

Make sure your DMM range is set to below 200Ω. Make sure all leads are floating and not touching anything including each other.

There should be no measurable resistance between leads except for the ones shown above.

 

[Thekahn]

Maybe you fried the 2.5V shunt reference? You should have around 15.5V at the top of R12 (closest to the meter board edge) and 2.5V at the other end of it. If you have the 15.5V and NOT the 2.5V, I would bet you smoked the 2.5V shunt reference.

Hi Jeff
So I have 14.98V on the top side of R12, and 0.140V on the other side of R12,. Does this mean R12 is blown and I need to replace it?
Thanks,
Chris

 

[jsteiger]

Hi Jeff
So I have 14.98V on the top side of R12, and 0.140V on the other side of R12,. Does this mean R12 is blown and I need to replace it?
Thanks,
Chris

No it won't be R12 it will be the 2.5V precision shunt CR1.

 

[nanuflas]

Hello Everyone. I'm having some trouble with my build. Everything works perfect and it sound great except that I get a pop when I hit the bypass switch and even louder pops when I switch between ratios. When I switch ratios, in addition to the pop, I get a huge spike on the meter. Any idea of what could be wrong?

 

[jsteiger]

Hello Everyone. I'm having some trouble with my build. Everything works perfect and it sound great except that I get a pop when I hit the bypass switch and even louder pops when I switch between ratios. When I switch ratios, in addition to the pop, I get a huge spike on the meter. Any idea of what could be wrong?

The meter jumping when changing ratios is not unexpected.

A pop when bypassing would likely mean there is DC present on the relay contacts which means there is DC present on either the output of the device going into the comp or the input of the device the comp is going into. The FC526 is transformer isolated at the input and output so there should be no DC from the comp itself.

I'm not sure about the audible pop when switching ratios. This should not happen though as far as I recall.

 

[Jroq82]

Good day everyone,

I’m having trouble with the 526 xfmr build. Once I plugged it in to the 511 rack I built with XLR I get no response from the comp.  I can hear a click once the rack is powered on. But I don’t see any LED’s light up, and turning the dial doesn’t do anything either for the LED’s.  No sound will pass through it either.  Does anyone here have any suggestions? Or ideas of something. Thank you in advance.

James

 

[jsteiger]

Good day everyone,

I’m having trouble with the 526 xfmr build. Once I plugged it in to the 511 rack I built with XLR I get no response from the comp.  I can hear a click once the rack is powered on. But I don’t see any LED’s light up, and turning the dial doesn’t do anything either for the LED’s.  No sound will pass through it either.  Does anyone here have any suggestions? Or ideas of something. Thank you in advance.

James

James, you will likely need the extension test jig so you can work on the module flat on a bench in front of you. You will need to test the audio path. I highly suggest reading back thru this thread as it will give you helpful clues on what to do.

 

[toga]

Hi,

PR3 burning was attributed earlier in this thread to an error on the DTO5 board. However, PR3 is now burning up on power-up with opamps removed.

Any thoughts? All components' placement/orientation checked.

NB. DTO5 (I-)  terminal is jumped to R27 replacing destroyed tracking. Just noting this, though the PR3 issue existed prior to broken tracking.

 

[jsteiger]

Hi,

PR3 burning was attributed earlier in this thread to an error on the DTO5 board. However, PR3 is now burning up on power-up with opamps removed.

Any thoughts? All components' placement/orientation checked.

NB. DTO5 (I-)  terminal is jumped to R27 replacing destroyed tracking. Just noting this, though the PR3 issue existed prior to broken tracking.

Sorry, I am away until mid next week.

 

[Homestudio]

Finishing my build of the fc526 kit and I can't find info as to the rv7 jump. Is that a fisical jump I need to do? Thanks

 

[jsteiger]

Finishing my build of the fc526 kit and I can't find info as to the rv7 jump. Is that a fisical jump I need to do? Thanks

Yes it is required. It says JUMP on the PCB and it says jump on the BOM for RV7, IIRC.