CLX-VU Build Thread (DBX 160VU ) UPDATE: REV 3

[Curran]

ok Disaster! sparks on the one compressor board in the LED section I believe. i had some smoke out of that board. then the other boards ratio pot smoked!!!!! I could not get mV's to read on either board. from the 15v rail's on the smoking LED board I got 47.7 VOLTS DC ?!?!?!? and could not get it to drop into mV range?!?!?!?! the other rail with the smoked ratio pot I could not get a steady mV reading. it went from 129.98 down to 78,8 on the mV setting of my DMM. It would fluctuate between these no matter how I twisted the trimmers r100 and r101. so I am guessing I fucked my entire build at this point. pretty fucking bummed. The VU meter on the smoking ratio pot side was pulsing as well. this was all over the course of ten minutes of trying to set the power rails. when I put my DMM on the G with a + or - side on the 15v rails I would get a -23.2 and a 23.2 reading on them. the 24v rail always read 50.4 on both boards

 

[Winetree]

It must have been quite a show. I'm just finishing two stereo builds. 
After Reading the posts, did you check the voltages before installing the I.C.'s?
Not being able to adjust voltages is usually a blown regulator. Did you install the right ones, in the right way.
Check direction of electolitic caps.
If you didn't check voltages first, I'd remove all chips, Vca's and start with the power rails first, replacing blown regulators and get the voltages right.
Checking blown I'C's is another matter.

 

[Curran]

no this was the 1st power up, so no chips where in. all the elctrolytics are in properly, when you say regulators do you mean the R100 and R101?

 

[Winetree]

No. R100 & R101 are the trim adjustors. You turn these to adjust the voltage.
LM317 and LM337 are the regulators.
Are they in the right positions and direction. Are the diodes (IN4001) in the right directions?

 

[abechap024]

ok Disaster! sparks on the one compressor board in the LED section I believe. i had some smoke out of that board. then the other boards ratio pot smoked!!!!! I could not get mV's to read on either board. from the 15v rail's on the smoking LED board I got 47.7 VOLTS DC ?!?!?!? and could not get it to drop into mV range?!?!?!?! the other rail with the smoked ratio pot I could not get a steady mV reading. it went from 129.98 down to 78,8 on the mV setting of my DMM. It would fluctuate between these no matter how I twisted the trimmers r100 and r101. so I am guessing I f**ked my entire build at this point. pretty f**king bummed. The VU meter on the smoking ratio pot side was pulsing as well. this was all over the course of ten minutes of trying to set the power rails. when I put my DMM on the G with a + or - side on the 15v rails I would get a -23.2 and a 23.2 reading on them. the 24v rail always read 50.4 on both boards

Ok. First of all you're not measuring anything in mVs at this stage. I'm confused a little by what is going on, your supposed to be looking at the +/- 15v rails while turning your resistors. If things are smoking, check what components your smoked, lucky they are all super easy to get from any generic electronic parts store.
Also, the 24v rails are bi-polar also? I  sense some general fundamental misunderstanding at this point, you always should measure from ground to the different points.

Also if you get sparks and smoke that is a very good sign you did something incorrectly and I would immediately power down and check your connections. Good place to start to look is incorrect soldering, solder blobs/ solder bridges. Also diode orientation.

A side note, why would you want to have the pots and everything hooked up when you are adjusting your power rails? Just more things to go wrong. I would check your wiring and orientation.
Good luck, don't get discouraged your probably almost there.

 

[Curran]

I though I was supposed to have everything hooked up except the chips, and YES there is some very fundamental dumbness in my brain. Reading the build manual I took the +/- 50mV to be that i had to get the test points to read that!!! I am to much of ab "A" to "B" brain. I miss very important subtleties until I get hit over the head with a flaming compressor!! LOL. I will disconnect everything, rebuild the led harness(Channel #1) and ratio pot ( Channel #2) look at my soldering on the back(Everything looks correct as far as orientation)
and figure out if I truly destroyed my compressor's. my wife is awesome and cheered my up right away with some parks&rec though which is nice. oh well.................

So I want the 15v rails to actually read 15V's give or take a bit right?! WOW this is so sensible no wonder i missed it. and the 24V rails should fall into line on their own correct? and I do NOT want to read my ground from the "G" on the test points of the board? but from a chassis ground reference? and another thing I have the boards on plastic standoff's, is this bad? I use them for the pedals I build for Strictly 7 Guitars

 

[abechap024]

I though I was supposed to have everything hooked up except the chips, and YES there is some very fundamental dumbness in my brain. Reading the build manual I took the +/- 50mV to be that i had to get the test points to read that!!! I am to much of ab "A" to "B" brain. I miss very important subtleties until I get hit over the head with a flaming compressor!! LOL. I will disconnect everything, rebuild the led harness(Channel #1) and ratio pot ( Channel #2) look at my soldering on the back(Everything looks correct as far as orientation)
and figure out if I truly destroyed my compressor's. my wife is awesome and cheered my up right away with some parks&rec though which is nice. oh well.................

So I want the 15v rails to actually read 15V's give or take a bit right?! WOW this is so sensible no wonder i missed it. and the 24V rails should fall into line on their own correct? and I do NOT want to read my ground from the "G" on the test points of the board? but from a chassis ground reference? and another thing I have the boards on plastic standoff's, is this bad? I use them for the pedals I build for Strictly 7 Guitars

Cool, yes you got it. Yes each power rail should be +15 and -15 respectivley. +/-50mv (just get em as close as you can, not a big deal). And the +/-24 rails you don't have any real control over and will drift depending on what kind of transformer you use and your line voltage etc. etc. The voltage of the +/-24 rails is not too critical as it just powers the output stage. I've had it as high as +/-30V and as low as +/-20V.

When checking if things are fried, resistors will have to look visually burned to a crisp and diodes you can measure with a DMM. Also you can measure transistors with the DMM (they are just 2 diodes connected together) With your pot that started smoking, it either is totally shot or just doesn't work were the smoke was let out, you can measure that too, but ultimately you will probably want to replace it.

 

[Winetree]

Finishing 2 stereo builds Ver. 2 and Ver. 3 boards.
Just want to make sure I've made all the Componet changes.
Reading all the posts is a little confusing
Have the BOMs been updated with the final changes?  Different values, Omit, Don't use.
What happened to the VER 2 docs?
The Ver 3 build manual is a combo of both 2 and 3 ??????
Just want to make sure everything's right  before first power up.

 

[eparg]

On another note my compressor is not passing signal on both channels. I have triple checked everything and can't find anything wrong. I tracked the input with a scope and I'm getting signal into the rms circuit. After the rms circuit I'm unable to trace the signal. The above/below leds respond properly. Not sure about the meter, the resistor that needs calibrated is still out of circuit. Anyone have a guess as to what is wrong? I'm using the kit abe provided for the THAT chip build. I can post pictures later.

The signal flow goes into the VCA not the rms circuit, the rms circuit is the start of the sidechain and converts the audio into DC so thats why you cant trace it.

Follow your signal to the that 2180 chip. Search for the datasheet if you need to know the in/out pins. If audio is going in and out of your vca check the second Tl082 chip as that is the make-up/buffer for the output of the VCA. Then it goes to the output section LM301 and the output buffer stage (2 transistors)

Also since both your channels are not working that is suspect.

On a side note, I've had people putting in all their chips before calibrating their voltage rails!! If you do not calibrate your voltage rails to +15/-15 before inserting your chips, you will obviously and very likely BLOW your VCA and other chips.

Not saying this is what happened to you, but thought I would mention it.

Thanks for leading me in the right direction Abe! I fixed the issue in both channels and now are both passing signal! I had soldered c12 and c21 into the wrong pads on the PCB, aligning them to the right. So to anyone else working on this project, when looking at multiple pads for a capacitor footprint align to the left (when looking at the text on the PCB facing you).


A few questions about the calibration:

4:1 ratio calibration R43 does not effect the level (also is CCW a typo in the manual, isn't fully CW no compression?) Do I need to solder blob the left pin and wiper pin together as you mentioned earlier in this thread? It isn't a big deal as it is only off by .07db.

Meter emulation calibration: R124 will not adjust the meter in either direction very far. I'm using the 1ma hairball meter. Is the solution to turn the screw on the meter to get it close to 0? I'm not sure if that is okay to do.


A huge thank you for this project, I can't wait to use it on a record in 2 weeks! 

 

[abechap024]

Finishing 2 stereo builds Ver. 2 and Ver. 3 boards.
Just want to make sure I've made all the Componet changes.
Reading all the posts is a little confusing
Have the BOMs been updated with the final changes?  Different values, Omit, Don't use.
What happened to the VER 2 docs?
The Ver 3 build manual is a combo of both 2 and 3 ??????
Just want to make sure everything's right  before first power up.

Yes, there are a few changes from rev2 to rev3. Nothing that drastic though. The Rev2 manual is still available. the link is here :
http://store.acsoundstudio.com/project-support/clx-vu.html

Hope that helps.

 

[abechap024]

A few questions about the calibration:

4:1 ratio calibration R43 does not effect the level (also is CCW a typo in the manual, isn't fully CW no compression?) Do I need to solder blob the left pin and wiper pin together as you mentioned earlier in this thread? It isn't a big deal as it is only off by .07db.

The blob trick was only needed for rev2. Honestly the 4:1 calibration doesn't really make a huge difference in practice. Though you should be seeing a good amount of change. (your turning the pots more than just once right? these are 20 turn pots

Meter emulation calibration: R143 will not adjust the meter in either direction very far. I'm using the 1ma hairball meter. Is the solution to turn the screw on the meter to get it close to 0? I'm not sure if that is okay to do.

It should be able to peg the meter harder than its been pegged before! Again the only thing I can think of is that your not turing the trimpots enough times.

A huge thank you for this project, I can't wait to use it on a record in 2 weeks! 

You bet! Thanks for getting it and hope it works wonderfully for you. I love mine on kick and snare during tracking. Though you have to be SOO careful not to destroy your snare tracks (I speak from experience ) When the meter is twitching, and lights blinking its usually just right.

Also a killer on guitars, bass!!
Rock on good luck!

 

[eparg]

Meter emulation calibration: R143 will not adjust the meter in either direction very far. I'm using the 1ma hairball meter. Is the solution to turn the screw on the meter to get it close to 0? I'm not sure if that is okay to do.

It should be able to peg the meter harder than its been pegged before! Again the only thing I can think of is that your not turing the trimpots enough times.

I did 20 360 degree turns and continued till I heard a click and stopped. On channel 1 I'm measuring 2.6 vdc at the pcb pad on r124 (the empty pad next to the silk screen r124), and channel 2 is reading a proper 15vdc. The maximum voltage I'm able to get into r108 is 2.6 vdc for channel 1, and 15 vdc for channel 2. Ignoring channel 1 for the moment, channel 2 reads 7.67 vdc on the other end of r108 and then ends up with .046vdc at the VU. R124 allows the meter to move to the right by about 5db on the scale. All resistor values are correct, and there are no cold solder joints. I am baffled at the moment, not sure what is going on. Maybe both TL071's aren't functioning quite properly? As for channel 1, isn't that pad directly connected to the +15vdc power? 

Thanks for taking time to answer my silly questions!

 

[abechap024]

It should be able to peg the meter harder than its been pegged before! Again the only thing I can think of is that your not turing the trimpots enough times.



I did 20 360 degree turns and continued till I heard a click and stopped. On channel 1 I'm measuring 2.6 vdc at the pcb pad on r124 (the empty pad next to the silk screen r124), and channel 2 is reading a proper 15vdc. The maximum voltage I'm able to get into r108 is 2.6 vdc for channel 1, and 15 vdc for channel 2. Ignoring channel 1 for the moment, channel 2 reads 7.67 vdc on the other end of r108 and then ends up with .046vdc at the VU. R124 allows the meter to move to the right by about 5db on the scale. All resistor values are correct, and there are no cold solder joints. I am baffled at the moment, not sure what is going on. Maybe both TL071's aren't functioning quite properly? As for channel 1, isn't that pad directly connected to the +15vdc power? 

Thanks for taking time to answer my silly questions!

Hmm...are you using the 3k3 resistor instead of the 10k resistor for the meter? (you should use the 3k3 with 1ma meter)

 

[ishish]

Trying to wrap up a stereo build here and I feel I am very close. One channel is passing audio and compressing beautifully! Yay. The other channel is compressing as well, but sadly, there is a lot of distortion in the signal at all times (even with compression at minimum). Any helpful ideas about where to start hunting down the problem? I've been very meticulous, and with one channel working I must not be too far off. Power rails at +/-15v and +/-23.7v.

 

[abechap024]

Trying to wrap up a stereo build here and I feel I am very close. One channel is passing audio and compressing beautifully! Yay. The other channel is compressing as well, but sadly, there is a lot of distortion in the signal at all times (even with compression at minimum). Any helpful ideas about where to start hunting down the problem? I've been very meticulous, and with one channel working I must not be too far off. Power rails at +/-15v and +/-23.7v.

I would power down both and switch chips in both and see if the problem follows the chips or on the board. If its the board I would look at all the diodes first (make sure they are in the correct orientation. And then the RMS unit.

 

[nuclues]

Iv'e have 15 volt at the power rails, there's light in the LED's - but there is only comming noise(hum) out of my Maschine. Any idea what's wrong?
2 IC's went up in smoke and I replaced them and now I'm thinking if the other IC's is spoiled
If that could be the reason,is there a way to test the IC's if they are working?
Yes- I've already tested and beeeped my soldering and the other components and checked the in/outputs if They had been misplaced..Everything should be in the right place ha ha
Please help me
Best from Nick

 

[eparg]

It should be able to peg the meter harder than its been pegged before! Again the only thing I can think of is that your not turing the trimpots enough times.



I did 20 360 degree turns and continued till I heard a click and stopped. On channel 1 I'm measuring 2.6 vdc at the pcb pad on r124 (the empty pad next to the silk screen r124), and channel 2 is reading a proper 15vdc. The maximum voltage I'm able to get into r108 is 2.6 vdc for channel 1, and 15 vdc for channel 2. Ignoring channel 1 for the moment, channel 2 reads 7.67 vdc on the other end of r108 and then ends up with .046vdc at the VU. R124 allows the meter to move to the right by about 5db on the scale. All resistor values are correct, and there are no cold solder joints. I am baffled at the moment, not sure what is going on. Maybe both TL071's aren't functioning quite properly? As for channel 1, isn't that pad directly connected to the +15vdc power? 

Thanks for taking time to answer my silly questions!

Hmm...are you using the 3k3 resistor instead of the 10k resistor for the meter? (you should use the 3k3 with 1ma meter)

Unit is up and functioning 99% (stereo link was working but isn't anymore.. will eventually figure it out). I had the 3k3 resistor there, still couldn't get enough current to the VU, swapped for a 1k, no change, and then a jumper. Figured out the problem was TWO bad TL071's... what are the odds?! Back to 3k3 and the meter is working perfectly.

Thanks Abe! 

 

[eparg]

Iv'e have 15 volt at the power rails, there's light in the LED's - but there is only comming noise(hum) out of my Maschine. Any idea what's wrong?
2 IC's went up in smoke and I replaced them and now I'm thinking if the other IC's is spoiled
If that could be the reason,is there a way to test the IC's if they are working?
Yes- I've already tested and beeeped my soldering and the other components and checked the in/outputs if They had been misplaced..Everything should be in the right place ha ha
Please help me
Best from Nick

First triple check that every IC is in the correct place. If you have a scope trace the input signal per Abe's suggestion:

Follow your signal to the that 2180 chip. Search for the datasheet if you need to know the in/out pins. If audio is going in and out of your vca check the second Tl082 chip as that is the make-up/buffer for the output of the VCA. Then it goes to the output section LM301 and the output buffer stage (2 transistors)

Study the schematic and you'll eventually find it, good luck!

 

[nuclues]

Thanks for replying Eparg, I wiil try your advice and beep my Way trough the Ic's 
Best regards from Nick

 

[jplebre]

Hey guys

So completed mine. Time to polish the little things now
Anyone else followed the suggestion to change the cap? (0.33uF)?

I managed to pull the sound I wanted from some snares exactly like the 160's I remember, but for the life of me the kicks just loose all body and get clicky, as if it wasn't fast enough (but this beast is that fast).

Eg. I can match the example in the sound cloud to 99.99%

I did do a silly mistake and installed the BC550 on the RMS section the wrong way around. I'm assuming the "timing cap" is the 22uF tantlum, maybe I damaged the cap?

Ideas before I start hacking at the board?

J