#1
So, I got this old self powered mixer board from my church, that didn't quite work right. So I salvaged what I could from it and I now have all this crap to use to make something cool, but I don't know what I should make. I guess whatever I end up making out of this I'll give credit to ya'll, so get them noodles working and tell me what to do!

A crap tone of PCB style 1/4th jacks and XLRs, some with individual connectors.


Close up on the XLR's with the individual connectors


Close up on the PCB style 1/4th jacks


Lots O jack holes


Really old volume readout rail


I'm assuming this is the power amp of the board, the caps look kinda bad, and feel really..how should I say it...hollow? Almost like wood or something, I'm thinking this is what was wrong with the whole board.


Overview of the board


This is what the board actually is.
#2
Hook one volume readout to a volume pedal and another to something else, like a wah or somethin'.

Do eet.
Obviously Fassa.
#4
The fifth photo. I just realized there's more than 2 readout rails but it'd be cool to somehow hook it up to a volume pedal.
Obviously Fassa.
#6
Quote by timbit2006
You could get it working and make money on it.


I really don't think it's ever gona work like it should ever again. Not unless I replace several parts, which I highly doubt they still make for this board, given it's like 20 years old.
#7
Quote by ethan_hanus
I really don't think it's ever gona work like it should ever again. Not unless I replace several parts, which I highly doubt they still make for this board, given it's like 20 years old.


The parts for a mixer are somewhat common. The only thing I can see being hard to find locally is the VU Meters. You can find those on any vintage radio component sites.

It just seems like a waste to me, taking out a few parts and leaving the rest.

You could make some Mic Preamps from it.
Or a three band EQ.
There's quite a bit you can make with parts found in a mixer. Pots, faders, resistors, you could take the voltage regulators out as well. Heatsinks can be re-used.
PCB mount components don't necessarily need to be mounted on a PCB. It just means it's a tiny bit harder to solder onto.

You mentioned it's self powered? I'm assuming you mean it's a powered mixer. You could take the amp out and give it back to the church to use for a monitor amp. This would require a new transformer though, unless you want to use that gigantic one currently in there.
The mixer must weigh a shit-ton, am I right?

There's just too many possible things to do with the mixer to list them all.
..I was watching my death.
#8
Quote by timbit2006
The parts for a mixer are somewhat common. The only thing I can see being hard to find locally is the VU Meters. You can find those on any vintage radio component sites.

It just seems like a waste to me, taking out a few parts and leaving the rest.

You could make some Mic Preamps from it.
Or a three band EQ.
There's quite a bit you can make with parts found in a mixer. Pots, faders, resistors, you could take the voltage regulators out as well. Heatsinks can be re-used.
PCB mount components don't necessarily need to be mounted on a PCB. It just means it's a tiny bit harder to solder onto.

You mentioned it's self powered? I'm assuming you mean it's a powered mixer. You could take the amp out and give it back to the church to use for a monitor amp. This would require a new transformer though, unless you want to use that gigantic one currently in there.
The mixer must weigh a shit-ton, am I right?

There's just too many possible things to do with the mixer to list them all.


Well, the thing the board was doing before I tore it apart was when everything was plugged in, and it was hooked up to the PA, you would turn it on and it would screech until your ears bleed or the PA system exploded. And this is not using the internal power amp, it wouldn't even work with the internal power amp.

The VU meters still work just fine, I just don't know what the heck to use them for, or how to read them, before my time.

Yeah, this mixer weighs about 60-80 lbs would be my best guess, it's no fun trying to move it.
#9
if I could get my hands on that many jacks and knobs, I'd build a maaaassive tubescreamer project thing.

I'd build several different versions of each section (different input filters, different clipping sections, blah blah, all that), but have them all disconnected from one another. then connect all the sections though the jacks with short patch cables.
so it's like one of those big old timey switchboards used for telephones, but allowing you to get any combination of tubescreamer sections and mods

if that makes sense
#10
Quote by james4
if I could get my hands on that many jacks and knobs, I'd build a maaaassive tubescreamer project thing.

I'd build several different versions of each section (different input filters, different clipping sections, blah blah, all that), but have them all disconnected from one another. then connect all the sections though the jacks with short patch cables.
so it's like one of those big old timey switchboards used for telephones, but allowing you to get any combination of tubescreamer sections and mods

if that makes sense


I was thinking of making like a junction box or something like that. Wouldn't I need like...a bunch of TS chips to do that?
#11
Quote by ethan_hanus
Well, the thing the board was doing before I tore it apart was when everything was plugged in, and it was hooked up to the PA, you would turn it on and it would screech until your ears bleed or the PA system exploded. And this is not using the internal power amp, it wouldn't even work with the internal power amp.

The VU meters still work just fine, I just don't know what the heck to use them for, or how to read them, before my time.

Yeah, this mixer weighs about 60-80 lbs would be my best guess, it's no fun trying to move it.


Did it explode?
You should've explained this from the start. I don't know what could be causing that and I think this is a salvage project now...
You could probe the power section only and see if your getting the correct voltage at each ribbon cable connector.

EDIT:
I'm four years younger than you and I know how to read a VU meter. Young adults these days...
..I was watching my death.
Last edited by timbit2006 at May 18, 2011,
#12
Quote by ethan_hanus
I was thinking of making like a junction box or something like that. Wouldn't I need like...a bunch of TS chips to do that?

yeah, you'd probably be able to recycle some caps and resistors from the mixer, but you'd probably also need to buy quite a few extra parts for something like that

just something I've always wanted to work on bu never had the parts around for
#13
Quote by timbit2006
Did it explode?
You should've explained this from the start. I don't know what could be causing that and I think this is a salvage project now...
You could probe the power section only and see if your getting the correct voltage at each ribbon cable connector.

EDIT:
I'm four years younger than you and I know how to read a VU meter. Young adults these days...


No, but it really sounded like something was gona explode. The thing has been sitting in the dust in a gym for God knows how many years, and it never got used.

They really didn't design this thing to come apart in one piece, so I kinda had to cut some wires and stuff to get the thing out. I could put it all back together, but I'd rather not. I'm thinking the VU meter acts just like a decibel read out, except through a needle style, it's just when I had it plugged in, all the needles were jumping back and fourth like crazy so I couldn't make sense of what they were meant for.

I'm thinking the caps in the power amp section are toast, cause they feel really dry, almost like redwood feels, you know, hollowish and hard.
#14
It sounds like you are missing a voltage there. Same problem happened with a mixer I was working on. Turns out one of the diodes was fried, so I was missing the 5V from the Power Supply.
I'd imagine if there were any LED's on this board they would be on when the mixer was turned on.

When you say Power Amp Section, are you referring to the one pictured beside the transformer?

One thing you could make with all those 1/4" jacks:
A pedal switcher. Look up the Carl Martin Octaswitch. I was working on a schematic of it a while ago, never quite finished due to lack of funding. I think I came out with around 100 to 200 dollars for parts. I'm going to hopefully make it this summer providing I get the time with work and college at the same time.
..I was watching my death.
#15
Quote by timbit2006
It sounds like you are missing a voltage there. Same problem happened with a mixer I was working on. Turns out one of the diodes was fried, so I was missing the 5V from the Power Supply.
I'd imagine if there were any LED's on this board they would be on when the mixer was turned on.

When you say Power Amp Section, are you referring to the one pictured beside the transformer?

One thing you could make with all those 1/4" jacks:
A pedal switcher. Look up the Carl Martin Octaswitch. I was working on a schematic of it a while ago, never quite finished due to lack of funding. I think I came out with around 100 to 200 dollars for parts. I'm going to hopefully make it this summer providing I get the time with work and college at the same time.


I think the only LED's on this board are for the peak on the VU meters. Yeah, the two boards next to the transformer is part of the power amp section, they have a bunch of large caps on them, I'll take it apart and show you what it looks like on the inside, I really think the caps are toast.

That octaswitch looks kinda cool, but wouldn't I need a bunch of DPDT switches to make it work?

Here's the pics of the Power amp




Last edited by ethan_hanus at May 18, 2011,
#16
Lots of those components are worth saving. You could probably build some DI's. And then also the pre amps and eq's are salvageable like TimBit said. Though on a console like that it may not be worth the trouble of keeping the preamps anyway.
If you're planning to completely gut it you do have a crap load of wire there which would be useful. And depending on what kind of trannies/jfets are in there you might be able to make some boosts or buffers.
#17
Quote by inkandlead
Lots of those components are worth saving. You could probably build some DI's. And then also the pre amps and eq's are salvageable like TimBit said. Though on a console like that it may not be worth the trouble of keeping the preamps anyway.


I'm curious, was the "TimBit" intentional?

Those caps, you said they felt hollow... You didn't even mention the goo coming out of the capacitor?
I've never actually gazed upon an exploded capacitor. Those caps have drained so much that the contents inside(I'm not sure what's in a capacitor exactly.) could not find anywhere to go and have exploded out.
It's a relatively easy fix for this mixer providing that's the only problem, which I'm going to say it would seem so. I'm not sure if the goo from the caps is corrosive, if it is I'd imagine there's damage to the PCB. Judging from the pics, there isn't any visible damage.

For the Ocaswitch you would need a bunch of switches. You'd only need to buy eight DIP switches and eight 3PDT switches.
I'm currently trying to work out a way to select the pedal order for each channel of the switcher. I haven't actually written anything down, it's all a general idea in my head. I can visualize the schematic in my head, just have to transfer it to paper.
..I was watching my death.
#18
Quote by timbit2006
I'm curious, was the "TimBit" intentional?



I think it was intentional. I was probably assuming that "tim bits" are a proper noun. Man, I am definitely going to Tim Horton's tomorrow...
#19
Quote by timbit2006
I'm curious, was the "TimBit" intentional?

Those caps, you said they felt hollow... You didn't even mention the goo coming out of the capacitor?
I've never actually gazed upon an exploded capacitor. Those caps have drained so much that the contents inside(I'm not sure what's in a capacitor exactly.) could not find anywhere to go and have exploded out.
It's a relatively easy fix for this mixer providing that's the only problem, which I'm going to say it would seem so. I'm not sure if the goo from the caps is corrosive, if it is I'd imagine there's damage to the PCB. Judging from the pics, there isn't any visible damage.

For the Ocaswitch you would need a bunch of switches. You'd only need to buy eight DIP switches and eight 3PDT switches.
I'm currently trying to work out a way to select the pedal order for each channel of the switcher. I haven't actually written anything down, it's all a general idea in my head. I can visualize the schematic in my head, just have to transfer it to paper.


I didn't know that was normal, I've stared at other large capacitors on power amps before and they usually have some kind of goo or glue or some crap around the caps. Guess that thing is toast.

Yeah, I don't have any money, so I gota use what I got. I was thinking about cutting out a bunch of channels and making it like a 2 or 3 channel mixer, simplify it, just straight up mixer board. I wouldn't have to cut any thing or solder any wires or crap like that, most of it is just plug stuff back in, where I plug stuff in is something to be debated, but that's not the point.