MixBuzz1 Build/Support thread

[gec]

Forever

 

[ilfungo]

Sorry I have a really strange problem
when I insert the MIX
On XLR (between pins 1 and 2) I read 18Vdc
Any ideas?

 

[Igor]

I haven't done this in a while, so just for my sake of sanity, I would appreciate a quick reply on this: say you have a power transformer with two 18V secondaries, the idea is to connect both 0V to CT and each of the 18V taps goes to its own ~18V hole. The PS PCB has a ground hole in the center which I should distribute to the star ground along with the grounds from XLRs and ground from center of main PCB?

Does that sound right?

EDIT: transformer wiring is OK. I get the correct volts and I'm using the 12V to light my on/off EAO switch (spec'd 24V, 12V gives nice even glow).

Now I'm confused with the ribbon cables, this is my first time using IDCs, so yeah re-reading the thread and inspecting pictures of working builds is helping a lot. Thanks guys

For 18-0-18V transformer:

18 to ~18.1
18 to ~18.2
0 to CT at power supply PCB.

For 18-0, 18-0 transformer (two secondary's):
Connect 18 of one secondary to 0 of other secondary and to CT at power supply PCB
(this is the central point of 18-0-18); than, 18 goes to ~18.1; 0 goes to ~18.2. Hope it is clear.

 

[Igor]

I have a weird problem
at this point instead of-12v I have 0 volts ...
when I turn on the compressor I have all the led (Meter) on....
could you help me?
thanks

-12V is actually 0V. Was answered some posts ago.

 

[Igor]

I turned the whole thing on its head and touched up / reflowed some unhappy solder pads. I did mixbuzz with new solder that I bought at a local store because I took a home leave to finish my projects and I couldn't wait for new shipment from iSolder. Anyway, have to get a hang of this one, the previous one flowed better on the other side of the PCB, this one doesn't want to.

Anyways, now I get signal on one channel that is properly received and compressed. Attack, release, sidechain models, threshold and makeup all work.

Issues:

-- Mix works like a LPF (not on sidechain, on audio) - I have to check wiring. The more "wet" I go, the lower the lowpass frq or maybe it's blending with a severely LPF'd signal and so it "sounds like" it's changing frq.
-- turbo doesn't light up the LED
-- LED meter doesn't work (no LEDs light up, ever, at any mode). Is my LED meter 12V hooked up properly? It should go to the header on top right of the PCB with 12V on the left and "-12V" (actually 0V) to the right?

LED meter's power supply should be connected to 0-12V (connector X1 at meter PCB).

The rest looks like check again with some patience, and you'll find some simple mistakes.

 

[Igor]

The other channel is still doing the triangular noisy small signal thing as referenced in previous posts. I removed the receiver chip and linked +In to Out but this signal degradation persists. The solder pads look OK now, but I'll have a go through all component orientation to see if that's the problem. Maybe some lytic is wrongly oriented?

EDIT: lytic C35R was oriented wrong, reoriented but nothing changed.

EDIT: VCA on not working channel needed one of the pins reflowed on its sub-PCB. Now it works!

Now to get some meter action.. any ideas on how I should approach debugging it??

EDIT: meter LEDs inserted wrong. Now all are on regardless of selected mode or signal level.

Yep. All we're people, not robots

 

[Igor]

Hello
I need your help
I finished the mix Buzz
and everything works
only problem is with LED METER
all remain always on, Q1 and Q2 both are hot
I double checked all connections but nothing wrong
What can it be?
Thanks

Please go some posts back, 2N4403 were supplied instead of 2N2222/2N3904 with some kits.
I checked this issue replacing the PN2222 on my MixBuzz1 to 2N4403; nothing was blown out, however, the meter was working wrong.
Just replace these transistors with PN2222/ 2N3904.

 

[Igor]

Thank you all for the help
Now the meter starts running ....
"Connect the wiper (central pin) with the bottom pin" is only for calibration or forever?
thanks

I needed some mv of offset to get right reading of meter at initial range (-22 db).

 

[baadc0de]

Thanks Igor!

Yeah I got everything working now except for the wet/dry and the turbo led.

The wet/dry seems to combine the signal with a weird severely LPF'd signal. The wires seem to be connected alright.. any ideas?

 

[Igor]

Mmmmm LPF'd signal..... I.e. no highs....
Checked the cap's in opamp's feedback?
Check all wiring, parts, solder joints, you almost here to make final calibration, listen and say WOA!

 

[ilfungo]

Sorry I have a really strange problem
when I insert the compressor
On XLR (between pins 1 and 2) I read 18Vdc
Yesterday everything worked
not today
commands no longer work
make-up makes a strange noise when the volume increases but does not change
Any ideas?
Thanks

 

[Igor]

Sorry I have a really strange problem
when I insert the compressor
On XLR (between pins 1 and 2) I read 18Vdc
Yesterday everything worked
not today
commands no longer work
make-up makes a strange noise when the volume increases but does not change
Any ideas?
Thanks

Dunno) Can be everything.
Check with ohmmeter 0 OHM between compressor's starground and XLR pin1.
Simplest troubleshooting algorithm:
Start from checking the power supply, than, do test procedure again.

 

[ilfungo]

I double checked PSU and everything looks good (all voltages are correct)
0 ohms between star ground and pin 1
I checked all the electrolytic and are in place
I do not know what to do ....
appear when I insert the compressor 18VDC between pins 1 and 2 of XLR IN
Suggestions?
Thanks

 

[Harpo]

appear when I insert the compressor 18VDC between pins 1 and 2 of XLR IN
Suggestions?

Don't feed your compressor with 18VDC from a broken sending device ?
Same 18VDC between pins 1 and 2 of XLR IN when not inserted into whatever (lonely island operating mode, nothing connected but AC mains) ?

So you have your compressors XLR input hooked up for an unbalanced connection (XLR-pins 1+3/2 connected), or why do you measure between XLR-pins 1/2 (shield/hot)? The balanced line receiver only operates the signal difference between XLR-pins 2/3.

 

[ilfungo]

Harpo, thanks !!!!!
My problem was an unbalanced Signal Generator
Following your advice I have found that it works!!
Thanks!!!

 

[Igor]

Harpo, thanks !!!!!
My problem was an unbalanced Signal Generator
Following your advice I have found that it works!!
Thanks!!!

WOA))))
This was funny.

Harpo, all thumbs up!

ilfungo: you had to specify at least that you feeding the compressor
from an unbalanced oscillator which has enormous amount of DC offset (I guess?)
Really, I was thinking about your issue some times today without finding any solution.
Anyway, happy it works.

 

[ilfungo]

sorry but still have problems ....
I connected to my sound card MIXBUZZ
when it is turned on, passing little signal and dark
changing meter by GR / OUT to IN I burned the 10ohm resistor
Suggestions?
Thanks

 

[zayance]

10R Resistors are acting like fuses on the +/- 15V PSU, so if it blows it means you have a problem, maybe a wire connection problem, or short somewhere?

 

[ilfungo]

some voltages in comparison with Igor:

"Some DC offset within +/-2 mV at the outs of THAT1646 etc is acceptable,
Please check the DC voltages between AGND (starground at PCB) and pins of input balanced line receivers (INA137 or THAT1246):

INA137/THAT1246
PIN VOLTAGE

1  0v
2  0v
3  0v
4  -15v
5  0v
6  0v 
7  +15v
8 not connected
As well, try to pull out balanced line receiver chip and check the voltages without it, on socket
(maybe a contamination? 1% from 100, but, everything can be)

That 1246 L no IC:

1  0v
2  0v
3  0v
4  -17.88v
5  +2.73v
6  +2.73v 
7  +17.90v
8  0v

That 1246 R no IC:
1  0v
2  0v
3  0v
4  -17.88v
5  +4.23v
6  +4.23v 
7  +17.88v
8 0
??? ??? ???



Compressor IN = Low and distorted sound....

 

[baadc0de]

Compressor IN = Low and distorted sound....

check for continuity on the VCA. Solder bridges, bad solder joints etc..

In my case, an ant (yes, the animal) was electrocuted under the VCA. It f** took all afternoon to find out and resolder.. now I have VCA higher in the air so I can plainly see what's going on!