Mackie 1202 VLZ PRO fixed!

[RDV]

I've got a 1202 VLZ Pro that my bass player found in a refuse heap outside an out-of-business audio repair shop. It was missing all screws, knobs, bottom half of chassis, and about half the little buss wires that hook the two boards together were snapped into.

So... I carefully soldered all the little buss wires back in place and bought a bunch of 4-40 screws and put the circuit boards back in place along with the power supply board as well.

With everything all back together, I found a mains cable and conducted the old 'smoke test', and no smoke happened and the power LED came on and I started to get hopeful.

So's I grabs a guitar(just knowing that there's really nothing wrong with this puppy and I've now got a free mixer), and plugs it in and plug up an amp, and... no sound. Nothing. No LEDs lighting, nothing.

I then started trying the other busses and got some sound from the headphone jack by hitting the solo button. I got hopeful again.

I decided to download the manual, and found in it that there is a second main output called ALT3/4. With this buss, you get everything except effects returns. So I find the appropriate jacks and hit the right button and VIOLA!! Sound!

I have my free mixer but I have no main output, thus no effects returns or XLR outs. Being out only $5.00 so far for the screws, I'm doing pretty damn good, but I would certainly like to find out why I have no main out. It's probably an opamp or two, but this thing is a forest of SMD opamps and such. I don't really know where to start.

So, do any of you techs know where I should start checking? I've got a couple of SMD dual opamps that I would love to fix this thing with.

Also, does anyone have any small knobs to fit a D shaft for sale or trade?

If you made it this far into this post, Then Thanks!

RDV

[vseriesamps]

This might be a little obvious but go through the whole face of the board and make sure nothing's muted or solo'd etc. that shouldn't be. And all your faders are up, your little gain knobs are correct and so forth.

Pretty easy on those things to miss some little solo switch on another channel - solo to mains or something - that's keeping all your other stuff from coming through. 'Specially when you're first getting to know them.

Good luck
K

[RDV]

This might be a little obvious but go through the whole face of the board and make sure nothing's muted or solo'd etc. that shouldn't be. And all your faders are up, your little gain knobs are correct and so forth.

Pretty easy on those things to miss some little solo switch on another channel - solo to mains or something - that's keeping all your other stuff from coming through. 'Specially when you're first getting to know them.

I know what you're saying, but this thing was laying out in the weather in pieces, and I had to put Humpty Dumpty back together again. What I'm trying to say is it only works from the alt3/4 outputs(which you get to by muting the channels) or if you assign the alt3/4 to the control room master. The Main master is dead as a doornail. Nothing at the LEDs or anything. I'll probably just leave it as is unless I can get my hands on a schematic cause I don't want to screw up what I've already got, which is considerable since I got it for free. It would work fine for a "live" mixer, or even for home recording(although not as convenient with only one working buss instead of two).

This thing had been in the shop for some reason and obviously they gave up and didn't get it fixed and scavenged the knobs and jack nuts.

RDV

[MartyMart]

http://www.mackie.com/support/downloads/manuals.html

The 1202VLZ "contractor" details have a block diagram which may help, its not a full schematic, but looks useful, or have you been here already ?

Good luck !
Marty. :wink:

[Paul Perry (Frostwave)]

RDV, what are the shafts for the knobs you want, 6mm or 6.3mm or what?

[black mariah]

You should really try the Tapeop forums. These guys could probably help you out since it's mostly recording engineers posting there.

[RDV]

RDV, what are the shafts for the knobs you want, 6mm or 6.3mm or what?

Gee, I don't really know. I just know I'll need a bunch of them. They're those plastic D shafted PCB mounted pots.

RDV

[bioroids]

There are some great lo-noise preamps on the VLZ series (supposedly).
I would use it for recording through the insert points if anything else wont work.

Luck

Miguel

[RDV]

http://www.mackie.com/support/downloads/manuals.html
The 1202VLZ "contractor" details have a block diagram which may help, its not a full schematic, but looks useful, or have you been here already ?

Yeah, I also emailed them cause I want to get the back half of the chassis from them. If they'll help me out with knobs reasonably cheap that would be cool also.

I just had a great experience with the Digitech customer support as they sent me a part for a pedal for 2 bucks plus shipping! I was shocked, but in a good way.

RDV

[RDV]

There are some great lo-noise preamps on the VLZ series (supposedly).
I would use it for recording through the insert points if anything else wont work.

Yeah the inserts work fine, it's just the Main Out that's bad. I could use the inserts to go to a recorder and return to the channels and monitor with the Control Room bus. It's far from dead. Really the only thing missing is the effects returns. I can't believe it was just abandoned like that, no wonder that place went out of business.

RDV

[RDV]

You should really try the Tapeop forums. These guys could probably help you out since it's mostly recording engineers posting there.

You're absolutely right, and I may try that, but this was a freebie and I don't really have any real sense of urgency about this, so I'm just taking it on as a learning experience and something to do while I'm off(from work) this week.

I'll tell you what, I'm running a distortion and a delay into one of the channels and EQing a bit and running the control room output to my Ruby amp. The Ruby has never been cleaner sounding ever, it really seems to match up impedance-wise.

RDV

[Johan]

does the headphone/C.R out work?..it sits after tha main out vol...
main out is both on top in the shape of phone jacks and on the back in the shape of xlr connectors. does either work?  does the meter show anything?...just trying to figure out where the chain is broken...
...also, the ground throughout the unit is through the chassis via the phonejack sleeve-connectors. if the pcb is out of the chassis it will behave very strangely...

...I have the schematic somewhere, if you "pm" me I could send it when I find it...

..dont be afraid of the SMD's...they are the same as regular components, only smaller...

Johan

[RDV]

does the headphone/C.R out work?..it sits after tha main out vol...
>>>Yes.<<<

main out is both on top in the shape of phone jacks and on the back in the shape of xlr connectors. does either work?
>>>No.<<<

does the meter show anything?
>>>No, not if you try to use the main out, but works fine for the alt3/4 bussed to control room.<<<

...just trying to figure out where the chain is broken...
...also, the ground throughout the unit is through the chassis via the phonejack sleeve-connectors. if the pcb is out of the chassis it will behave very strangely...
>>>I put the PCB back in the chassis.<<<

...I have the schematic somewhere, if you "pm" me I could send it when I find it...
>>>Done.<<<

..dont be afraid of the SMD's...they are the same as regular components, only smaller...
>>>They're so tiny but I've got a couple of SMD sized OP275 just ready to hop in if need be.<<<

Thanks Johan!

RDV

[Johan]

RDV...

refering to the schematic that you now have...
page 8, upper left corner. Main Mix level. you have two testpoints YL and YR. these are marked on the back side of the PCB. if you still have signal here, the next point to check would be the link over to the next pcb. its most likely one of those two IC's ( u48 and u49 ) or perhaps the pot itself...my guess would be U49 since U48 is only set up like an inverter for the balanced output.

good luck...its a great little mixer, so its definetly worth spending a few minutes on...ecpecialy at the price you got it for  :wink:

Johan

[RDV]

RDV...

refering to the schematic that you now have...
page 8, upper left corner. Main Mix level. you have two testpoints YL and YR. these are marked on the back side of the PCB. if you still have signal here, the next point to check would be the link over to the next pcb. its most likely one of those two IC's ( u48 and u49 ) or perhaps the pot itself...my guess would be U49 since U48 is only set up like an inverter for the balanced output.

I've got signal at YL & R.

RDV

[RDV]

I fixed the damn thing thanks to Johan! Here's a picture of the offending surface mounted JRC2068:
I replaced it with a OP275 I ordered by mistake one time.

This marks a couple of firsts for me, the first mixer repair of any kind and the first surface mount part soldering of any kind. I sharpened the tip of my soldering iron for about a half hour before I strarted!

Thanks again Johan! Need some caps?

RDV

[KORGULL]

Cool!! I was rootin' for ya. That's a good mixer. I almost bought one, but went with a Behringer instead 'cause Mackie stuff was a bit more$$$than I wanted to spend at the time(-later sprung for a pair of Mackie's HR 824 monitors with no regrets though)
It's great when you can turn trash into treasure - there's a nice thrift store dumpster I shop in all the time down the street. Somebody's gotta rescue all this poor abandoned "junk" :cry:  
-Most of it still works... which makes it that much more painful when I rip an IC or motor out of it. :twisted:

-Just installed my first 2 surface mount ICs a couple weeks ago in a video transmitter - finally got some use out of the magnifying glass attached to my "third hand" PC board holder.
See ya.

[RDV]

Man, I needed a magnifying glass! I'm not sure the other OA just wasn't soldered in good, as I was able to pry it up with no heat. I stuck the crap out of the new one. Now I've just got to order the sides, bottom and knobs.

RDV