Auditronics 110A revival

[Whoops]

last week i had about 4 channels in and the MC4 module and was able to turn it on and test a few mic pres. couldn't get the program sends to work. i just added a few more channels, turned it on and fried a resistor on the MC4.

does anyone have suggestions on best way to proceed? recap electrolytics and tantalums on every channel before testing further?

I would do that for sure.
Would recap all the channels first

would it be possible to bypass the MC4 and entire master section?

Second step, after the recap would be to standalone test each preamp one by one.
Have a simple external PSU, feed the voltages needed. Connect signal at the input and listen for the output.
Does the channel turns on? does it passes sound? Does it sound good?
Next channel and so on

If you could so some measurements it would be great, like Freq Response, noise, etc.
That way you could compare all the channels  and see if any channel is not on "Average" with the others.
If you can't  do the measurement tests, you have to do listening tests with the channels and see if any of them sounds funny or really different than the others.

If you have a Bench variable PSU with current meter, you can also check the power draw of each channel and see if they are consistent with each other. If you have a channel with an higher current draw than the others, troubleshoot it.

This way when you insert the channels in the console at least you know  they are all good.

You can also test the Master section without channels.

 

[Whoops]

I don't have the correct schematic for this.
I have schematics from a 24 channel, 8 bus, and the mc4 module from that looks different. On the one I have, when you press pgm 2 and 3, that becomes the master send.

You should also try to get the correct schematics.
As long as your desk doesn't have custom modifications from the last owner, there should be service documentation or schematics for you desk somewhere.

Who was the last owner?

Have you tried Auditronics experts? Who repaired these consoles?

Old dealers of Auditronics stuff?

What Studio equipment repair and Console repair Companies/Techs are in Tennesse (Nashville and Memphis)?
Those companies over there should know

 

[dukeofearl]

I'm putting in an order for caps now. Panasonic FM for the electrolytics.

What about the tantalums? I have read some threads here suggesting replacing tants with electrolytics or film caps.  There are a bunch of 10uf 25v tants, and a couple .22uf 50v. And then one .82uf 20v "tubular solid tantalum."

 

[Whoops]

In some circuits Tantaluns are used for a reason,  although polarized they have different technical characteristics than Electrolytic.
I've read they  have a bad freq responde for Audio signal and high distortion,  but sometimes they need to be used because of the particular job they are doing in a circuit (they are temperature stable), because they are small or because they have low ESR.

Tantalum capacitors don't dry out, so you don't need to replace them if they are not blown.
My advise is if the tantalum's are in the Audio path, replace them with something better, Panasonic series Lytic. For the .22uf 50v and the  .82uf 20v  you can use film caps, just be sure they fit the pcb as tantalums for the same value are much smaller.
As for the other non Audio path tantalums if you dont have any blown tantalum  in your modules I will just leave them, don't see any reason to change.
Check the schematics, mark where the Tantalum caps are, study what each of them is doing

check this video, it gives some nice explanations on why there are not better caps than othera,  they all have different technical characteristics and should be used in a circuit according to that:

https://www.youtube.com/watch?v=67M7fsbLUIU&t=64s

 

[dukeofearl]

thanks i'll check that out. looks like my modules are very slightly different than the ones i posted, being 110a rather than 110b.

on the 110a schematic,  c5, c17 and c18 are .5 rather than .1 -- i guess still 100v?

there is a .0082uf 80v in my modules that i can't seem to find on the schematic. also, i can't find c26, the .039uf 250v.

still sorting through the differences here...

if anyone has the component location diagram for the 110a, that would be awesome

 

[Whoops]

thanks i'll check that out. looks like my modules are very slightly different than the ones i posted, being 110a rather than 110b.

on the 110a schematic,  c5, c17 and c18 are .5 rather than .1 -- i guess still 100v?

there is a .0082uf 80v in my modules that i can't seem to find on the schematic. also, i can't find c26, the .039uf 250v.

still sorting through the differences here...

if anyone has the component location diagram for the 110a, that would be awesome

It's a simple module, get the closest schematic you have  to your circuit.
Trace your circuit, where do the .0082uf 80v connect on one side, where does it connect on the other side, mark that on the schematic. Follow the circuit from both side until it reaches and IC, transistor, transformer or inductor them you know where you are.
It should be easy.

 

[nielsk]

Actually it is the power tants that should all be replaced, as they can go dead short and there is no advantage to tants over modern electrolytics in that application.
I would get it up and running and audition the audio path tants before you start shotgunning it, they seldom go bad and often sound quite good. You may find you loose the "character" you like by replacing them with electrolytics...
You can certainly use a buss amp as a mix out, on some of their designs it is a better circuit. They did some really weird stuff in the master sections.
If it uses one of those cmos chips for the monitor path you will want to change all that to something sensible, it is usually not too difficult to replace the source switching with relays

 

[theninjacowboy]

Just letting you know I have a full original 110 manual covering all revisions and tons of extra documentation. I am working on scanning it and getting it uploaded somewhere but if you need anything specific let me know. I'm working on getting my 501 up and running and I have a clean 110 frame I am looking for modules for.  Cheers!

 

[clintrubber]

Just letting you know I have a full original 110 manual covering all revisions and tons of extra documentation. I am working on scanning it and getting it uploaded somewhere

Sounds good, thanks already!

Enjoy the 501/110 resurrection!

 

[dukeofearl]

Haven't had tons of time to work on this but did recap the power electrolytics and tantalums and got 16 of the 17 channels working. The mc4 module works now. It's basically a matter of spending a long time wiring the molex to a patchbay. And deciding if I want to restore the control room section. Oh yeah, and possibly balancing the individual outputs...

 

[jvancorduroy]

Just letting you know I have a full original 110 manual covering all revisions and tons of extra documentation. I am working on scanning it and getting it uploaded somewhere but if you need anything specific let me know. I'm working on getting my 501 up and running and I have a clean 110 frame I am looking for modules for.  Cheers!

Did you get the 501 up and running .I would be interested the hear about any modifications you did.
Cheers
Dave