DIYers love and HATE dream...MCI 500

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roginator

Well-known member
Joined
Nov 7, 2005
Messages
467
Location
CROatia
Here in one half of modules...I got to do big job.....I love that desk....

I bought 2 complete desks.......

NOW I WILL:FIX IT....

MCI500DIY2.JPG


I feel good....pananannnannnaaa
 
Yeah, well get out your de-soldering iron. I see original orange electrolytics from 1979.

When you replace them, supersize them in value and you will get less bass tilt. I did.
 
I used Panasonics.

I made 220 uf's 470uf's I made 100uf's 220uf, and in some places I dared to use a jumper wire, and expected offset hell and noisy switches, but I guess I chose the right places for them.=) Only a few places, tho.

I think I had the only 500 desk with balls.

A 20hz square wave leveled out nicely on the top tilt after the recap=)
 
here is a recap list for an MCI 500 console I did several years ago. There are a few versions so make sure this makes sense for your modules. Either way it should be helpful. The part numbers are from digikey.com . They are Phillips/BC axial caps. You can raise the value on some of these caps if they will fit but I remember there being a space constraint.

You may also want to consider upgrading or removing the VCA. If you want to remove them altogether you would need to replace them with a set gain amplifier and an audio fader. If you are considering this or putting automation in, I have a full set of NEW metalwork which will accommodate a P&G fader. PM me if interested.

http://www.coralsound.com/MCIchannelRECAP542.pdf

Good Luck
 
Wow .. a lot od info on MCI HERE

I allready selected good looking modules from scratched...also I cleaned them all....my frame is 43 modules.....

I have ready set of 32 input modules, 4 Stereo groups, master, aux send and 5 other modules for comunications and stuff......

on input modules I found that it is REV B modul... what that means????

is that recap list for rev B?
should I change any other parts on modules?
also I dont need vca?!?!?!??!.....Im planing to use it with my Ensoniq Paris DAW....

.....
 
here is a recap list for an MCI 500 console I did several years ago. There are a few versions so make sure this makes sense for your modules. Either way it should be helpful. The part numbers are from digikey.com . They are Phillips/BC axial caps. You can raise the value on some of these caps if they will fit but I remember there being a space constraint.

Interesting you should mention the BC axials. I recently recapped a pair of channels in a friends MCI 400 series desk with BC axials & it completely changed the sound of those channels. They sounded very clear in a sterile way, but not as exiting & coloured as those original orange coloured caps. In fact the owner was disappointed with the sound.

If anyone out there can help I`m trying to find a diagram for the channels on this desk. People have sent me them before but this appears to be a rather unusual revision. The boards are marked PCA4300-0241. I`ve asked here before but maybe there`s some new members now ???
 
hi Rob,
The original caps in my 416b are light blue. Maybe your friends is a late version when they were also building the 500 series? I too used
BC axial in 12 channels and was not completely happy. I had enough to do 6 channels each in 25v and 40 v. The 25 volt had better tone in the
hi mid and low hi's. The 40 volt channels had the bigger bottom end.
The original caps sound like they have both tones covered but not as tight of a bottom. I bought a spare master channel from Buttachunk (thanks Butta!)and it sounds very good. It has nichicon. I'm thinking I'll try these in a couple channels when I get a hold of some.

Is your friend using the original power supply? I use a pair of 6 amp Lambda's and they make the recapped original sound sick.

Lance
 
Interesting you should mention the BC axials. I recently recapped a pair of channels in a friends MCI 400 series desk with BC axials & it completely changed the sound of those channels. They sounded very clear in a sterile way, but not as exiting & coloured as those original orange coloured caps. In fact the owner was disappointed with the sound.

I have had a good experience with BC axials in general. The last MCI 500 I recapped was actually with Panasonic HFS caps. I updated my cap list to the BC caps because the Panasonics are discontinued and the BC's are easy to get. I have used BC caps in lots of other stuff (Neve modules, ADR, etc) with great results. I have no doubt that they sound a lot different than the original orange caps. I find the orange caps are generally in pretty bad shape though. BTW, I am talking about AML138 series . Ususally I am looking for a cap that doesn't color the sound. I leave that part up to the circuit design, transformers, etc. Especially with an MCI 400 which is pretty darn colored!

Is your friend using the original power supply? I use a pair of 6 amp Lambda's and they make the recapped original sound sick.

We changed the PSU's on the MCI 500 to Acopians. Both Lambda and Acopian make fantastic supplies. I prefer Acopian. The original MCI supplies are pretty good (especially compared to what Trident would ship with their consoles!) but are noisy (fans) and difficult to service.
 
This 400 series is different from the diagrams I have because it gas a pair of driver transistors near each op amp. Nobody seesm to have the info for this apart from a dealer who wants a fortune for it.

The power supplies for this desk are original. From memory it has 3, with an extra one for phantom

I pretty sure the caps I took out were orange, but they might have been light blue, it was some time ago that I did the recap.

This desk sounds fantastic, with a really vibrant live sort of sound, the 2 channels with bc`s sounded lifeless in comparison. The trouble is the owner hasn`t done much in the way of servicing, & there are some flaky channels, which is why I need the diagram.
 
Hi Rob,

You did't happen to get the numbers off those driver transistors did you ?

Are the op amps LM394CH type , supermatch pairs ?

How do you indentify the interstage capacitors ? these are generally the ones that need updating to new higher values. ex. 100uf to 220uf etc etc .... ?
 
roginator requested a pic of the MCI 500 we rebuilt/modded so here it is. I don't have a pic of the whole console right now but here is a pic of a module. The mods included:

Uptown Automation
Set gain amplifier and Uptown interface electronics from Purple Audio
No VCA
Recap
New Power Supplies
Insert Defeat Relay activated from the old automation switch
Monitor hard mute activated from the old automation switch
Stereo Aux mute activated from the old automation switch
new metalwork
master section audio upgrades
reterminated to DL multipin connectors
oh yeah.....and it's BLUE

DSCN3207.JPG
 
MCI "2001" opmps were Harris HA-911 chips, perhaps hand selected. Harris exited the opamp biz a jillion years ago, so finding replacments will be tricky.

I just uploaded the 911 spec sheet here (not linked yet in my "library" page):

http://www.brianroth.com/library/ha911.pdf

Notice the 50 VDC max rating (ie, +/- 25V rails). Not too many newer opamps can meet that spec.


Bri
 
I reckon the MCI 2001 opamp is a Harris or Intersil HA-2645
i've acutally seen these in a MCI-500 channel strip.
These have a max voltage supply of +/- 40V. Given that the MCI-500 runs off +/- 38V, this would be about right.

I have some MCI 2001 ICs if anyone is stuck.

The MCI-500 is a damm rocking console, unfortunately by this stage in their life they are a lot of work to restore.

Check out all the modules i've racked on my website.

The owners of these racks totally love them.

The VCA is a weak point in the console. I ditch the VCA in my racks

http://www.proharmonic.com/mci.htm
 
Im at the stage to recap my console....I will go with your caping info and cap upgrade....also if there is any cap need to be changed in other modules please let me know.......
 
The VCA is a weak point in the console. I ditch the VCA in my racks

luckily you don't have to worry about a fader with your racked modules. For a console upgrade it gets a little expensive to ditch the VCA. You would need something along the lines of a P&G 3000 fader and a new daughterboard to make up the lost gain and add a mute circuit. IMO it is still worth it.


BTW we also replaced all of the DIP sockets in the console. The original ones are finicky to say the least.....
 
for sure ditching the VCA in a console is a expensive proposition. Although
there is nothing wrong with using Alps faders and the gain could be made up on the pan buffer.
One thing i'd check is what IC is used to do the current to voltage conversion on the output of the VCA. Some boards i've seen have 741's here. You could do much better!
Also check the motherboard underside for dry joints / cracks around the socket pins, this seems common
 
What is Acopian PSU upgrade...any web link to them or other source...Let me know....I would like to upgrade my MCI
 
ouups ...I found that PSU web site....wich model did you use on upgrade MCI coralsound?????

any specs...exact model???
 

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