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

[jsteiger]

Everything checks out with the 2622. After your tests  I also put a sine wave thru pins 1&2 together as + and  3&4 as - and it amplified and put the signal out on pins 5&8 fine

What about a picture of a working unit? Or I can send you more of mine besides the one in Reply #301

Not to name drop but I dropped my last 2 built units off to Ryan Hewitt yesterday so I don't have any here currently to take more pics of.

There is not much at all between the 2622 and TP1. Just the BC550/560 transistors, their R's (R36, R37, R41, R42) and C15. Maybe you should try replacing the transistors? If so I would do it one at a time, although the voltages looked normal.

 

[toga]

Hi,

just getting back to this build. Finding it difficult to get hold of the 2n5087 and 2n5088 transistors without paying the mouser postage premium. Any suitable transistor alternatives? Thanks.

 

[jsteiger]

Hi,

just getting back to this build. Finding it difficult to get hold of the 2n5087 and 2n5088 transistors without paying the mouser postage premium. Any suitable transistor alternatives? Thanks.

BC550C and BC560C will work fine but the pinouts are turned 180˚.

 

[420troll]

Not to name drop but I dropped my last 2 built units off to Ryan Hewitt yesterday so I don't have any here currently to take more pics of.

There is not much at all between the 2622 and TP1. Just the BC550/560 transistors, their R's (R36, R37, R41, R42) and C15. Maybe you should try replacing the transistors? If so I would do it one at a time, although the voltages looked normal.

Pulled and replaced transistors they were fine in parts tester, but put new ones in anyway.  Looked at all the R's you mentioned they all look right then pulled and tested C15 its fine and still nothing at TP1 at the calibration level.
:'(

-30 dBu is 0.024volts ac right?

So stumped after about 30 hours of troubleshooting this, Pissing me right off! Having  finished two other projects in the meantime with no problem at all.  JLM opto  comp kit is next, I wonder if it will be working before this? Or what will become of this CAPI kit? I wish it would just work. I love the sound of good compressor and have no doubt  this one sounds amazing when its working properly.

 

[jsteiger]

Did you check DCR from the outside of the 2622 mu-can to the winding leads when you had it out last time?

 

[420troll]

Did you check DCR from the outside of the 2622 mu-can to the winding leads when you had it out last time?

Yes. Checked that like you asked three days ago.

 

[420troll]

So I pulled up R42 and and the signal does not get to that spot, when I take it out of bypass then it kills my sign-wave going into the unit and turns it in to noise at the balanced input jack. The two dials control the level of the noise at the top of R42,  I find that strange maybe c17? anyhow thats what i got today

 

[jsteiger]

So I pulled up R42 and and the signal does not get to that spot, when I take it out of bypass then it kills my sign-wave going into the unit and turns it in to noise at the balanced input jack. The two dials control the level of the noise at the top of R42,  I find that strange maybe c17? anyhow thats what i got today

C17 and R40 form the Zobel network for the 2622 so its likely not that. Pulling one end of R40 will effectively remove the Zobel from the circuit so taking it out of play if you care to check.

Were you able to look up the spec of your DMM? Most importantly the input Z? If the Z is high like I mentioned in the email, I would be convinced its the 2622. Oddly enough, this will be the first bad 2622 from the new winder and we are well over 2k units shipped but sh*t happens. In fact, at this point I'm happy to send you one just so we know 100%.

 

[420troll]

OK well its hard to tell if both are flipping or not. At least you know something is happening. You will have to check the relay pins for continuity.

The pic attached shows what should have continuity in ACT mode. It will be the other contacts when in BYP. Make sure both poles of the relay are functioning correctly. K1 is the input relay and K2 is for the output.

So i have been going back in to the circuit surprised by what was happening with  the test signal at the input and decided to pull K2 out to see if I could hear K1 switching since it was not passing the continuity tests, and I can hear only silence so i will try the BYP switch, but hear it click on power up.  I must have been getting bad readings at R71 and R73?

 

[jsteiger]

So i have been going back in to the circuit surprised by what was happening with  the test signal at the input and decided to pull K2 out to see if I could hear K1 switching since it was not passing the continuity tests, and I can hear only silence so i will try the BYP switch, but hear it click on power up.  I must have been getting bad readings at R71 and R73?

So the relays are not changing over when flipping the BYP switch? If that's the case then maybe the 4V3 zener is not in its right place? Could have been switched with a 914?

You should be able to test both relays for continuity in both states from the back of the PCB.

 

[420troll]

So the relays are not changing over when flipping the BYP switch? If that's the case then maybe the 4V3 zener is not in its right place? Could have been switched with a 914?

You should be able to test both relays for continuity in both states from the back of the PCB.

I tested both relays for continuity in both states from the back of the PCB and K1 failed thats what was trying to say in the previous  post


K1 was bad  when I put K2 in its spot i can hear it switching with the BYP switch

 

[jsteiger]

I tested both relays for continuity in both states from the back of the PCB and K1 failed thats what was trying to say in the previous  post


K1 was bad  when I put K2 in its spot i can hear it switching with the BYP switch

Wow very odd. I can send you a replacement.

In the meantime, I would jumper over the pads on the missing relay just for testing the audio path etc. The thick green lines in the attached screenshot would be for the module to be in ACT mode. Jumpers are shown for both  relays.

 

[Thekahn]

Hi guys, new to the forum. I've built one successful VP28, but I am hitting a pretty big hiccup when i'm testing my newly built 526-Litz.

I am reading 10.02 V DC at TP 9. I am reading 2.503 V DC at MTR point #11.
I've sent a 1k test tone thru my DAW and i'm getting  243.3 mV AC into the unit, as well as  243.3 mV AC on the output of the unit while bypassed.
I have turned RV2 clockwise probably 20-30 turns clockwise.
input gain, output gain, attack, and release are all fully CW, and 20:1 Ratio is confirmed selected.


Once I turn it to active, GR OFF, and SC HPF disengaged, I am getting the following readings, with my DMM set to AC voltage, one lead on the ground lug, and the other lead to the following:

TP 1: 56.6 mV AC
TP 2: 1.14 V AC
TP 3: 9.17 V AC
At the output, i'm reading 18.29 V AC


With the unit active, and GR on, i'm getting the following readings:
TP 1: 56.6 mV AC
TP 2: 0.951 V AC
TP 3: 7.0 V AC
At the output, i'm reading  15.25 V AC

With the unit active, GR on, and SC HPF In, i'm getting the following readings:
TP 1: 56.6 mV AC
TP 2: 0.928 V AC
TP 3: 7.46 V AC
At the output, i'm reading  14.87V AC

I have confirmed that none of my capacitors , diodes, or transistors are in backwards (I triple checked but who knows).  And I did as Chunger suggested,  I put all the resistors in before soldering anything that way everything is copasetic.  I also spent about 4 hours yesterday double checking every single resistor with color code method, I checked every single capacitor, transistor, switch, IC.. I literally went through the build with a fine tooth comb.  I cannot see where this went wrong.
I’ve also used 3 OP amps and get the same test values +/- a couple of mV.  I’ve also tried a couple of different slots in my Lindell 506 power supply with very similar results too.  At this point the only thing I can think of is maybe a bad solder joint. I have confirmed there are no solder bridges as far as I can tell (and I’ve stared at the thing at least 4 hours lol).  Any help would be awesome, thanks in advance.

Kahn


Oh and by the way this is an awesome community that I'm proud to be a part of, and Jeff has been extremely helpful thus far.

 

[jsteiger]

-30dBu is 24.3mV AC not 243mV. Not sure what is up with the measurement system but something is not right in that regard.

 

[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

 

[Tschem]

Hi Jeff, sorry to bother you again.
Same old problem, also after installing a fresh DTO5:
@0.025V Input:
0.006V @ TP1
0V @ TP2

Input of DTO5 == 0.006V
Output of DTO5 == anode of D4 == ~0.140V
cathode of D4 == 0V

Do you think it might be D4? any suggestions how to go on from here?

 

[jsteiger]

Hi Jeff, sorry to bother you again.
Same old problem, also after installing a fresh DTO5:
@0.025V Input:
0.006V @ TP1
0V @ TP2

Input of DTO5 == 0.006V
Output of DTO5 == anode of D4 == ~0.140V
cathode of D4 == 0V

Do you think it might be D4? any suggestions how to go on from here?

D4 is part of the peak circuit. The anode of D4 should equal the output of the DTO5 since there is a PCB trace directly between them. The ONLY thing between the output of the DTO5 and TP2 is C8. If you have signal at the output of the DTO5 then you will have signal at the negative end of C8. You should also have the same signal at the positive end of C8. C8 and TP2 are directly connected by PCB tracks.

 

[Tschem]

It's definitively C8. 0.140V on cathode, 0 on anode. direction is correct, i also re-soldered the solder joints without any effect.
guess i have to find a replacment.
thx a lot for support!

 

[420troll]

All the new parts have been put in relays, transistors, but in the audio path still have the same problems and test point problems. Audio sounds thin and the test points all fail. I am getting 1.48vAC at output with all knobs CW with 0.024vAC going in.
Guessing this week is going to be be going over the test points and calibration procedures a few more times.
I notice that when monitoring the input at the edge connector when active mode is engaged the input voltage of 0.024vAC changes and drops to 0 volts and when in bypass it is normal 0.024vAC same thing happens at the relay on the side that heads to the input transformer, it drops to zero.
I was really hoping you would have sent a new transformer like you said you would to be safe.

 

[jsteiger]

All the new parts have been put in relays, transistors, but in the audio path still have the same problems and test point problems. Audio sounds thin and the test points all fail. I am getting 1.48vAC at output with all knobs CW with 0.024vAC going in.
Guessing this week is going to be be going over the test points and calibration procedures a few more times.
I notice that when monitoring the input at the edge connector when active mode is engaged the input voltage of 0.024vAC changes and drops to 0 volts and when in bypass it is normal 0.024vAC same thing happens at the relay on the side that heads to the input transformer, it drops to zero.
I was really hoping you would have sent a new transformer like you said you would to be safe.

Last I remember hearing you found a problem with a relay. After that, sending the 2622 didn't cross my mind when I sent you the pot. I will make a note to send one now.

Are you 100% sure both of your relays are switching over completely?