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Author Topic: SSL 4000 behavior  (Read 9973 times)

gregdubuis

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SSL 4000 behavior
« on: November 17, 2010, 07:11:31 PM »

Hi all,

I just finished 2 days of maintenance on our SSL 4000.
But, I still have a defective compressor on channel 47.

When I switch the compressor in, the audio is muted.
So, to test the compressor card, I swapped the compressor card with another one and it works.
This experience shows "normally" that the compressor card of the channel 47 is defective.

I took out the compressor card and make measurements on it, the card seems to be good.
To be absolutely sure, I put the extensor inside the console and plug the channel 47 on it.
I make some new measurements (with alimentation) and everything is good.
Then I decided to listen audio inside the channel 47 and the comp works now...

I removed the extensor and put the channel back inside the console and then the compressor still mute the audio!
Morality, the compressor works with the extensor plugged and doesn't works without the extensor.
I moved the compressor card in another channel and it's the same behavior...
This, drive me nuts!!!

Any inputs are welcome (ssltech, Jim Williams)
Best regards.
Greg
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Greg Dubuis
Sound Engineer & Electrical Engineer
Route de Genève 17
CH-1003 Lausanne (VD) Suisse
Phone:   +41 21 323 08 80
Email:   greg@studioduflon.com

Visit Studio du Flon at http://www.studioduflon.com
And at http://www.myspace.com/studioduflon

Nick Sevilla

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Re: SSL 4000 behavior
« Reply #1 on: November 17, 2010, 10:17:17 PM »

So,

In it's normal channel 47, the compressor does not pass signal.

In another channel slot, it does work normally?

Now, with the card extender the compressor works in any channel. Correct?

To me this is a classic symptom of a bent pin, or a dirty connector somewhere.

I would clean all connectors on the card, and in the console.

Cheers
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David Kulka

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Re: SSL 4000 behavior
« Reply #2 on: November 17, 2010, 11:59:45 PM »

This may have nothing at all to do with your problem, but years ago I ran into a similar mystery, and finally found that for whatever reason, the + and - sides of a bucket switch were not switching exactly in tandem, which would cause some dynamics sections in that bucket (not all!) to latch up when the switch was turned on.

Again, your issue is probably something else, but thought it as worth mentioning.
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sodderboy

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Re: SSL 4000 behavior
« Reply #3 on: November 18, 2010, 06:44:44 AM »

It's also a potential cold-solder sitch.  Really seems contact related.  I would try putting it in the console with a couple of spaces open to the right and have a gentle poke around with a chopstick while the comp is in and muted.
And check the ends of the motherboard connector as well as for bent pins.  Perhaps it is a seating issue.

Did you measure the voltage rails at the IC's? very important.  That card has extra regulation n'stuff.

Mike
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gregdubuis

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Re: SSL 4000 behavior
« Reply #4 on: November 18, 2010, 06:06:32 PM »

Hi all,

Many thanks for all your answers!

Nick:

Yep, in the channel 47, the compressor stops the signal.
In another channel slot, same issue.
Yep, with the card extender, the compressor works in any channel.

At the beginning, I was thinking like you, so I decided to clean all the connection but at the end, no change...

David:

Really interesting! Hum, not for you (I'm sorry) but maybe for me.

Sodderboy:

But why the problem follows the compressor card?
It's not the channel board (99% sure).
No bent pins also.

The voltage measurement is good with the card extender.
Maybe the next step is to dump 8 channels out and plug only the 47 into the console.
So I can try (if there is enough space) to do the measurement without the card extender...


Like I told you, this drive me nuts!
Best regards.
Greg
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Greg Dubuis
Sound Engineer & Electrical Engineer
Route de Genève 17
CH-1003 Lausanne (VD) Suisse
Phone:   +41 21 323 08 80
Email:   greg@studioduflon.com

Visit Studio du Flon at http://www.studioduflon.com
And at http://www.myspace.com/studioduflon

Nick Sevilla

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Re: SSL 4000 behavior
« Reply #5 on: November 18, 2010, 06:09:41 PM »

"But why the problem follows the compressor card?"

Because... the problem HAS TO BE in that compressor card.

"When all else fails, the only thing left must be the truth."

Cheers
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ssltech

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Re: SSL 4000 behavior
« Reply #6 on: November 21, 2010, 03:36:17 PM »

This 'voodoo' problem happens a lot with the dynamics cards.

The voltage regulators on-board latch up when the little electrolytic capacitors RIGHT by the 10-ohm fusible resistors dry out. -Powering up the bucket (and cycling the power) a few times makes them work sometimes and not others; you may want to try that test to see if it matches your unit's behavior.

Replace the half-dozen or so electrolytic caps and repeat the bucket-power-cycle test. -Once you're assured about the problem being fixed, you might want to do the caps on the other dynamics cards, since these things tend to 'cluster-fail' with age.

Basically, the SPEED at which the rails come up causes one or other regulator to latch up (I forget which) and so one power rail doesn't come up, and the card passes no signal.

Sorry, been out of the country  for a few days, in complete "off-the-grid" mode, so I'm just catching up.

Keith
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MDM (maxdimario) wrote on Fri, 16 November 2007 21:36

I have the feeling that I have more experience in my little finger than you do in your whole body about audio electronics..

Brewery

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Re: SSL 4000 behavior
« Reply #7 on: November 22, 2010, 07:43:56 AM »

sorry to go off topic here, but i have a different problem that might have a similar cause:

one of the buckets doesn't send proper vca data to the computer on a few channels. in mix view those channels are all the way down, even though they work properly, and the meters show correct vca values.

powering the bucket off and on a few times makes them all work again. i always thought it might be an analog card problem, but could it have to do with the voltage regulators?

also, the fader status lights don't light up when booting the computer, like on the other buckets.
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ssltech

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Re: SSL 4000 behavior
« Reply #8 on: November 22, 2010, 10:02:36 AM »

How many channels does your console have? -If it has enough to require a second Analogue Input board, then the lights thing is not a worry. -Also, if the lights and switches test under "!TES" shows that they all operate correctly, don't sweat it.

As for the VCAs, you have to be aware of how the DC is being fed around. There's no bucket-wide voltage regulation, so there's no possibility that I can think of where the cause could be in any way related.

Also, the console meters and VCA levels sometimes don't loop through the computer, specially if your console has Total Recall.

How are you measuring the VCA signal to the computer? -It shoudl be observed under "!TES" also.

Keith
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MDM (maxdimario) wrote on Fri, 16 November 2007 21:36

I have the feeling that I have more experience in my little finger than you do in your whole body about audio electronics..

Brewery

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Re: SSL 4000 behavior
« Reply #9 on: November 22, 2010, 10:23:56 AM »

i have to admit i never measured anything, since toggling the bucket off & on a few times always solves the problem. still a bit of a pain.

the console is 56 channels, and once all channels show up fine in mix view, everything works like a charm.

i will look into it when i have a bit more downtime, not anytime soon though..

as always - thanks for the help keith!! and sorry to hijack greg's threat.

erik
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ssltech

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Re: SSL 4000 behavior
« Reply #10 on: November 22, 2010, 12:15:48 PM »

Hmmmm, I seem to recall that 56 is the maximum number with a single input board, so that's not likely.

Check the "!TES" menu and see what you can learn from that. -I'll scratch my head for a bit.

Keith
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MDM (maxdimario) wrote on Fri, 16 November 2007 21:36

I have the feeling that I have more experience in my little finger than you do in your whole body about audio electronics..

gregdubuis

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Re: SSL 4000 behavior
« Reply #11 on: November 22, 2010, 05:02:18 PM »

Hi ssltech,

Thank you for your answer, it sounds really interesting!
I will try it as soon as possible and let you know what's happen.

And please, don't be sorry, you just made my day!
Best regards.
Greg
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Greg Dubuis
Sound Engineer & Electrical Engineer
Route de Genève 17
CH-1003 Lausanne (VD) Suisse
Phone:   +41 21 323 08 80
Email:   greg@studioduflon.com

Visit Studio du Flon at http://www.studioduflon.com
And at http://www.myspace.com/studioduflon

Brewery

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Re: SSL 4000 behavior
« Reply #12 on: November 23, 2010, 06:48:08 AM »

ssltech wrote on Mon, 22 November 2010 18:15

Hmmmm, I seem to recall that 56 is the maximum number with a single input board, so that's not likely.

Check the "!TES" menu and see what you can learn from that. -I'll scratch my head for a bit.

Keith


i did all the !TES tests, and strangely they also seem to fix the probem somehow.
first on the vca ramp up test, the pattern was all over the place, and a few channels would always stay muted, but then, after starting the test over a few times, it ramped all odd channels, and then the even ones without a problem. i can't figure out the seperate channel test, when pressing a fader swith the absolute led lights up, but no vca action (on any channel)

the analogue input always works on all channels, and shows correct values.

lights test also works on all channels, but still - one bucket and a few other channels don't light up on boot up, ever. with just one analouge card installed.


this is really not a huge deal, but i can never rely on the computer working properly right from the start.
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ssltech

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Re: SSL 4000 behavior
« Reply #13 on: November 23, 2010, 06:59:32 AM »

Don't sweat the lights and switches. Power up is a semi-random affair and not indicative of a problem.

!TES 'fixing' a problem is a wierd one... -Check the 50-way ribbon seating at the console and computer ends.

Keith
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MDM (maxdimario) wrote on Fri, 16 November 2007 21:36

I have the feeling that I have more experience in my little finger than you do in your whole body about audio electronics..

guy_4

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Re: SSL 4000 behavior
« Reply #14 on: November 25, 2010, 04:14:58 PM »

To Keith,
Doesn't it remind you of a similar thread at another forum ?   Cool

To Greg,
You did not tell us what SSL you have ( E or G ), and the year of manufacture.
Anyway, I would suggest you to implement this mod to ALL of the Dynamics card of your console.
On the output of the 78L12 : solder a diode ( typ. 1N4148) with the Cathode on the output of the regulator, and the Anode to ground.
On the output of the 79L12 : also solder a diode, but wire it with the Anode on the output of the regulator, and the Cathode to ground.
Wire the diodes on the copper side of the card, between the pins of the regulators.
Afterwards, when you'll power on/off a channel, the Dynamics card will always power on, 100% reliable.
Without the diodes you need to be lucky if you have all the Dynamics cards of the channels working after a console powered on.....
Also, take this opportunity to replace the electrolytic cap ( 10
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