Auditronics 110A revival

I'm getting started on bringing one of these back in action after sitting for a long time. So far I've recapped the power supply. I've been able to get signal from the preamp out on a few channels. And I got the echo send to work. It's a 17-channel, 4-bus, 110a.

I've read many threads on this and have ordered an acopian psu for the +/- 15v. I plan to use the stock psu for the 24 and order something else for the phantom since that is broken.

I am putting in an order of a few parts and wanted to ask suggestions. I plan to start by replacing the electrolytic caps.

IC chips - I know there are many suggestions of upgrades but at the moment I'd like to just get this working. Is there a point in replacing these even if they work? Do they get old like capacitors? Mine is full of LM301, LM318 and LM709.  I have located the 301s and 318s on mouser, but the 709s appear to be a special order.

tantalum caps - i've seen suggestions here to replace these

I can't seem to get any of the channels I've got working to send to the program or master bus or show anything on the meters. I wonder if there's an issue with my MC4 module. That's why I was thinking to replace the ics in these. There's not much else in there. 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.

here is the mc4 module that i have

i have a few channel strips in the console and this module. does the control room module need to be in there for the pgm and masters to work?

i'm getting ahead of mysef, but i'm going to have to wire up a patchbay. there are pre-amp outs in the back that are easy to connect to, but this is pre eq (and unbalanced). i was wondering if there is a better spot to get direct outs. could i just tap into the fader outs? is there a reason not to do this? then i can get the full channel strip with eq and attentuation. i'd have to figure out the balancing regardless...

The ICs are good forever, or until you blow them.

LM709 is a rather special case. Fully slugged it is a poor '741. However de-compensated it is faster than any op-amp for a decade after. And some elaborate tricks evolved around it when it was the only "good" opamp. I'd be reluctant to mess with that. I would however add a few spares to some furture order: '709 is exceptionally easy to blow-up. Despite the makers claim, I could do it with a momentary output short.

okay, i'll order some spares for each of the ic's rather than replace them all. i did have a smoky start when i first fired this thing up so some things could have been toasted. the only thing visibly toasted is a resistor and a cap on the CRM module. working more slowly and carefully now!

i located this signal flow diagram for the 18-channel version. so it looks as though this should work if i just have some channel strips in, the mc4 and the pgm output cards. i can leave out the mbm, crm, fm4, sm, hpc. i don't plan on using the monitoring section.

Do you have the schematics for the Channel modules and for the master section?

it would be easier for members to help you by seeing that

Does this Auditronics console has still circuit sections from the Spectrasonics company?

I remember seeing similar consoles to that one when I visited Memphis. There was one on display at the Rock N Soul Museum and another one at the Stax Museum.

I have pictures somewhere

Whoops said:

Does this Audiotronics console has still circuit sections from the Spectrasonics company?

I remember seeing similar consoles to that one when I visited Memphis. There was one on display at the Rock N Soul Museum and another one at the Stax Museum.

I have pictures somewhere

Click to expand...

The 110 wasn't a Spectrasonics desk....

I've seen a number of cases of "smoke" in 110 modules due to shorted tantalums on the PSU rails.

Bri

Brian Roth said:

The 110 wasn't a Spectrasonics desk....

I've seen a number of cases of "smoke" in 110 modules due to shorted tantalums on the PSU rails.

Bri

Click to expand...

Hi Brian, do you know which Auditronics consoles had Spectrasonics circuits?

thank you

Whoops said:

Hi Brian, do you know which Audiotronics consoles had Spectrasonics circuits?

thank you

Click to expand...

I'm also curious about the BEGINNING of Auditronics.


Bri

I have some sales literature for the Auditronics "Grandson" console.  I'm not sure there is any schematics (but it does include the block diagram earlier posted in this thread).  I'll scan and download. 

Downloaded the brochure to the Technical Documents section under Auditronics...

In case you need full schematics, long while ago I got in touch with someone who had scanned the whole lot, wanting some $20 for it. If you happen to need that set, I can dig up who it was (I myself was just looking for a few modules which were already available, so didn't obtain the full set then)

I found my photos of the Auditronics desks I saw while visiting Memphis Museum's, you can check them in this thread.
There's also some info on the consoles:

https://www.gearslutz.com/board/high-end/101227-muscle-shoals-desk-2.html

that stax console is cool.

i should probably do those tantalums as well then...

i do have some schematics, but they are for the 24 channel version. very similar but a few differences. apparently with the smaller one like mine, when you switch the MC4 module to "2-channel," the pgm-2 and pgm-3 act as the main stereo outs. i think i will mostly use mine in this mode. i wonder if i should even think about somehow altering the master section.

here's the output card...

mc4 but for the 24 channel version

input module schematic

mc4 schematic

Nice that you posted the schematics,
this way I think it's easier for member to follow you.

Also, just to be sure, have you seen the Auditronics schematics on the tech docs section?

https://groupdiy.com/index.php?topic=51783.0

thanks for the link. i hadn't seen that.

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?

would it be possible to bypass the MC4 and entire master section? hook into the pgm 2 and 3 lines and feed it to a different line amp so it bypasses the mc4, faders and line amps? put in a different summing amp or even feed this into an external line amp?

input module