SSL 4000 E/G Mix Bus Level Issues

[nycsudio1]

Hi there,

My SSL 4000 E/G series has a problem in the mix bus. The left channel signal is about 3db lower than the right channel. If I turn on the oscillator and send 1k tone to the quad bus, all 4 meters work fine, however when signal is sent from any of the 40 channel strips to the mix bus the right channel meter shows 3db gain and when recording from the console output to to a stereo track in pro tools also shows the same difference in level. I don't have the cards installed on the back bus so I can't see if the problem is happening on back bus as well.

I personally don't notice any difference in level in the monitor speakers.

I wonder if this is a calibration issue.

I also noticed that occasionally the levels will get as close to a match as possible but for the most part the 3db difference is constant.

I appreciate any help or suggestions.

Thanks.

Louis

[marcmozart]

See if this helps:

http://forum.sslmixed.com/index.php?topic=301.msg1368#msg1368

However, a defective ribbon would only affect channels on either the left or right hand side (relative to the Centre Section).

[nycsudio1]

Hello,

Thanks for your reply.

I checked the link and as I read this "Problem: Level for LEFT BUS from Channels in Bucket 1-8 dropped by a few dB" it makes me believe that if this was the case in my console the problem would be happening on one or two buckets. The problem I have here is consistent and identical on all buckets (40 channels).

I will definitely check the ribbon cables today as soon as I get to the studio, meantime if there's any other suggestions, please don't hesitate to share.

Regards.

[sintech]

Hi, with the oscillator to quad, the tone is injected into the 025 card, hence why you don't see an issue when metering.

This is an 026 card issue. I would prove this by swapping RF and RB cards, and see the problem moves.

[sintech]

If the problem moves with the 026 card:

Using the patch bay and a bantam lead, you can decipher if the issue is Pre or Post VCA. Either by cross patching Left to right.. or with a scope.

[nycsudio1]

I am on my way to the studio to try your suggestions now.

Thanks again for the help.

[Showcase]

I also suspect a 026 card, and probably that bipolar capacitor

[nycsudio1]

I spent all day working on the board today and followed all the advices suggested here.

Here's what I found:

As soon as I lifted the Center Section the problem went away for the most part and both channels were almost a  match. Left channel level was a hair lower than the right channel. I then made sure that both 026 cards were seated properly in their slots.

Upon touching both 026 cards I realized that the Left Channel card would make noise every time I touched it while nothing happened when I touched the other card, so my guess is that the pins on the back of the connector need to be re-soldered. (If I am wrong, please let me know)

When I lowered the center section the problem returned and the left channel was again about 3db lower than the right channel.

At this point I went under the console and touched all the cables underneath the center section and the problem went away.

At one point both channels were a dead match but then the left channel return to a hair lower level than the right channel. I recorded a mono signal from one of the channels to pro tools and in fact the left channel was a bit lower as the VU indicated.

Bottom line, it appears that I have two problems affecting the same function. I will re-solder the connector tomorrow and will again look underneath the center section in order to find out if there is still a cable that is not properly connected or damaged.

I appreciate all the suggestions so far, and if I am missing something or should consider doing something else, please feel free to share your thoughts.

You guys rock.

Thanks again.

[marcmozart]

Before you start soldering, find the exact source of the problem. Clean the edge connector contacts of the 026 cards, and also the connector on the Centre Section PCB.
Use a Q-tip and Isopropyl-Alcohol, test again. Optionally - apply some Caig ProGold to the contacts.

If you have the extender cards of the centre section you can also find out with a multimeter where the problem lies. It doesn't have to be the edge-connector, it could also be the cable or connector that goes to the patch.

[nycsudio1]

I tried cleaning the connector and the card but it didn't work. The difference in level is minimal at this point but still existent. I am going to see if there's anything else that could be wrong on that section. The board is fully recapped and all caps on the center section cards are new so at this point my guess is that it is probably an intermittent connection somewhere.

Thanks.