11v is out on a 4k. Any Clues where to start?

[Enginemark]

Our 11v LED indicator is out, and the console logic is not behaving normally (wont switch modes, etc).  Anyone have a clue where to start looking?

[kilmister]

Check PSUs then switches and fuses below console.

-Paavo

[Enginemark]

PSUs are showing all the voltages as being normal (based on the LEDs anyway).  I checked all the little push button breakers on the bucket power switches, but I guess I don't know where the Fuses are.....

[TheMixfactoryNYC]

The 11v is tapped off the +18v rail.

Check the regulator cards in power supply.
If you switch the cards around you should get an idea.

[sintech]

If all the rails are up at the power supply end,,. you could quickly check 11v is getting to the channel modules. If all is good you know the issue is after the power inlet to the 651

Turn the power off, lift the 651 and pull all the cards, if theres a 11v->18v short on one of the cards, then the indicator will be back on, if not.. you know it's a problem with the power distribution.

If it's the cards..You can then visually inspect the boards for any burning.

Replace the boards one at a time until the 11v indicator goes off!

Once you have the bad card in your hand.. you can measure the short, then pull each IC in turn checking the short has cleared.. and so on

[Artur D'Assumpção]

Hi Mark,

Like I told you before you should check the backplane on the back of the 651 center section for the presence of the 11v.

You can proceed like Andy suggested, take all center cards out and probe on the backplane if the 11v is present. That will allow you exclude a PSU problem if the 11v is presence, and the otherway around if it's not.

Installing one center card at a time will allow you to quickly pinpoint which card is bringing down the 11v rail.

Cheers,

Artur

[Enginemark]

Wow, this has turned into quite the mystery here at our end.  We've had a tech here for like eight hours and he can't find the issue either.  When we initially checked the 12v (or 13v or 11v or whatever you want to call it) on the backplane of the 651 it was reading close to 17v.  When we turn off the buckets one by one the 11v volt LED on the face of the 651 slowly comes on (a bit at a time as the buckets are switched off) until it looks almost normal when only the 651 is powered on, and at that point the voltage is around 13v on the backplane.  But, even so (with the buckets all off), the 11v LED on the top of the 651 is dimmer in Record mode than it is in Mix Mode.  The logic switches are still not acting totally normally even with the buckets all off.  The tech is saying he has seen "partially" blown fuses that act like resisters, which can cause this odd draw down on the 13v, but we can't find any fuses at all on this console (apart from the ones in the power supply) so we can't even find a fuse to check. We've tried removing cards from the 651, with no real success, although the oscillator card did make a slight improvement when it was pulled.

[Enginemark]

Also, just a quick question.  Can you swap the regulator cards around in the PSU with impunity?  They aren't calibrated to a particular voltage value?

[xmax]

Yes all cards work in any spot, make sure +18 and +11 (7v,13v whatever you want to call it), are connected together in the desk via biccs, I will get you pin i.d. in a minute. Also make sure none of the bicc pins pushed up into the connector. N

[xmax]

I don't have access to a manual at the moment but it sounds like you lost the -6.5 volts.

[TheMixfactoryNYC]

Wow, this has turned into quite the mystery here at our end. 

If the regulator cards are ok in power supply for the +18v rail and 13v I would next that the connector for the fuses on the power switches for buckets is totally in for the +18v for the 651.

This happened to me twice before and that was the issue.

The connector if you move the cables sometimes comes loose and looks ok but until you push it all the way in and reset the fuse it doesn't see the full +18v.

[Enginemark]

Finally figured it out.  The part that was bad was the bucket power switch that is next to the circuit breakers under the patch bay.  Part #RS 316-995.  Our tech eventually called a friend who is a tech in LA and he says he is seeing a lot of these switches go bad in recent years.  I guess they are all reaching end of life right around the same time all across LA.  There is a carbon build up inside the switch, and they start to act like resistors.  Ours eventually caught fire yesterday (!) after moving around some of the power supplies and reconnecting things, and switching those switches back and forth a number of times.  We eventually just bypassed all of them temporarily while we order new ones (and run this weekends sessions), and voila, the lamps across the entire console are a bit brighter and all our voltage issues disappeared as if by magic.  Logic behaving normally.  Thanks for all the suggestions.  Unusual problem with a unusual culprit....

[Artur D'Assumpção]

Mark,

Thankfully you found it! One another issue solved!

Thanks for sharing the solution, I am sure someone somewhere will need this!

Cheers,

Artur

[TheMixfactoryNYC]

Finally figured it out.  The part that was bad was the bucket power switch that is next to the circuit breakers under the patch bay.  Part #RS 316-995.  Our tech eventually called a friend who is a tech in LA and he says he is seeing a lot of these switches go bad in recent years.  I guess they are all reaching end of life right around the same time all across LA.  There is a carbon build up inside the switch, and they start to act like resistors.  Ours eventually caught fire yesterday (!) after moving around some of the power supplies and reconnecting things, and switching those switches back and forth a number of times.  We eventually just bypassed all of them temporarily while we order new ones (and run this weekends sessions), and voila, the lamps across the entire console are a bit brighter and all our voltage issues disappeared as if by magic.  Logic behaving normally.  Thanks for all the suggestions.  Unusual problem with a unusual culprit....

Yeah its one of the weak points of the consoles in my opinion, the switches to the buckets.

They are tough to suss out and difficult to replace. Plus the wiring is so tight. Not fun to tech out sometimes.