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Wiring up my bantam patch - earths and encouragement needed!
Old 24th September 2006
  #1
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7 Hz's Avatar
Arrow Wiring up my bantam patch - earths and encouragement needed!

Hey,

I really need to get on with wiring up my small studio. I have everything planned, it's going to be a 1 u 96 way patchbay.

My main issue is earths. I have a secondhand unused patchbay. It is the standard non-switching earth design. I see there are a few ways to wire in the earths on these types of patchbays, but what distresses me is even the experts don't agree on the best way to do it!

Knowing that earths can cause untold problems, I am apprehensive about wiring this up, no matter what earthing scheme I use.

I have heard of switched earth patchbays. I find it funny that these aren't more common. Are they not a better solution? Then earth can follow signal quite happily.

My second hand patchbay is showing a little corrosion on one side of the chrome frame as well, which makes me less worried about throwing it away and just buying a proper nice new switched earth one.

Finally, I have seen these things get wired up. I know it takes ages. Am I right in thinking about a full 50 hours for one patchbay plus the connectors on the other sides of the cable? An I crazy trying to do this myself? (I have a reasonable amount of skill and experience with soldering, and have designed and built my own compressors etc).
Old 24th September 2006
  #2
Gear Head
 
gjuodenas's Avatar
 

Several Hints:

Make sure you have a mechanical support bar running the length of the patchbay to tie wrap the wires to. Do not let them hang straight down from the patch points.

Use a premium silver solder such as "wonder solder"

Make sure you understand proper soldering technique. Make sure the metal is hot enough to melt the solder. Also, use a good temperature controlled iron with an appropriate tip, a spade tip large enough to heat the metal.

Heat shrink the wires. Do not leave any earths exposed, they might short against other wires.

Take your time. You may be better served to unscrew each pair of "normaled" patchpoints (top and bottom) and solder them in a vice. Then screw it all back together.

On any used or older bay, it is a good idea to spray a high quality contact cleaner into the the patchpoint and insert a patch cable several times to get a good cleaning.

You are right, there are many earthing schemes in place (a very large topic for discussion) and you will find that people feel really strongly about their scheme being the best. Do not forget that the grounding scheme involves every piece of equipment and every electrical outlet. Whatever you do, make sure you have a master groundin scheme and wire your bay accordingly.

Good luck,
George J.
Old 24th September 2006
  #3
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If you are looking for specific grounding advice, it would help to have more info about you're basic setup. Analog, digital, or both? Balanced, unbalanced, or both? Normalled, not, or both?

(Mini rant: why is is that people so often ask technical questions here, but neglect to give details about their gear and their setup?)

Anyway, I generally recommend connecting all shields at the patchbay, including a "looping ground" with each set of normalling jumpers, and cutting shields at every balanced input (except mic ins, of course).

If you're combining balanced and unbalanced things get a bit hairier. The patchbay should be wired the same way, but the other connectors change, according to the specifics.

In 30 years of installing studios I've never seen a switched earth patchbay, though some of the more expensive connectorized bays have grounding that is programmed by jumpers, or by "set and forget" type switches on the inside. But I've never run into a bay with switched normalling contacts for the grounds. The mechanism would probably be complex and expensive.

In our shop, where we build cables and patchbays every day, we find that as a general rule of thumb, an experienced wiring person can finish 6-8 balanced "ends" per hour. That includes cable prep, dressing with cable ties, and testing, but not planning or labeling. The normals are "extra".

A fully populated TT patchbay has 96 balanced cables going to it, each with 2 ends, so it has 192 ends total. An experienced wiring person should be able to do that job in 24-32 hours. The normalling jumpers might add another 4 hours. So now we're up to 28-36 hours, plus some time for planning it beforehand, and labeling it afterwards. A studio owner who does ok work but does not have wiring expertise might take 50% to 100% longer, so your estimate of 50 hours is probably pretty close.

If possible, look at a patchbay that has been professionally wired and try your best to copy the details and make it look the same. The terminals on TT jacks are close together, you need to really do neat work. Avoid blobs of solder and wire "whiskers" that almost touch. Borderline problems can turn into real problems with a just little bit of handling and stress on the cables.
Old 24th September 2006
  #4
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7 Hz's Avatar
Thanks for the amazing replies!

I have been present during two studio wire ups, directing the wiring guys, so I have seen how it is done.

I am planning to make it as neat as possible, with all cables supported where needed.

My gear is mostly balanced, but several unbalanced things as well:

01v96
mpc 4000
keys - pro one, korg ms 10, roland mks 30
just a few bits of outboard at the mo - master room studio b reverb, effectron adm 1024 delay, urei 7110 compressor, home made Moog vca compressor, decks plus scratch mixer, few other bits and pieces
To be added - maybe a fatso or some other compressor, nice outboard eq, super jupiter, DI / mic pre etc

The patchbay will have at least half of the contacts semi-normalised. All analogue, maybe the odd digital patch, but none planned atm. Line level keyboard studio most of the time, occasional mic work.
Old 25th September 2006
  #5
Gear Maniac
 
Peter Morrison's Avatar
 

Quote:
Originally Posted by David Kulka View Post
Anyway, I generally recommend connecting all shields at the patchbay, including a "looping ground" with each set of normalling jumpers, and cutting shields at every balanced input (except mic ins, of course).
ok, I am trying to follow this.
Connect all shields at the patchbay- got this one
include a "looping ground" - so on normaled patches I should solder a ground from the ground on the upped jack to the ground on the lower?
cutting shields at every balanced input - so I should float the grounds at the inputs going in to outboard, mixers, converters, whatever (except mic ins for phantom reasons)

if you have a picture of one of your properly wired patchbay I would love you forever, in the gearsluttiest way

thanks
Peter
Old 26th September 2006
  #6
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7 Hz's Avatar
Yeh, I am still confused with the grounding soloutions for my setup.

Am I best getting balanced lines everywhere? Does that mean setting up transformers on the outputs of all my unbalanced stuff? The main thing that isn't balanced ATM is my home made compressor, so perhaps I should transformer balance that on the ins and outs?

Any other stuff is likely to be balanced TBH, apart from the synth outputs.

I would just hate the do it the wrong way and have to redo 96 earths once everything else had been wired up! That would NOT be neat!
Old 27th September 2006
  #7
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Tim Farrant's Avatar
 

Well I have the opposite theory, I connect sheilds at the equipment end, and leave it off at the patchbay. Treat all unbalanced circuits as balanced, ie, at the equipment end, tie the sheild/cold to sheild and hot to hot. At the patchbay, wire it as balanced. Makes it easier to wire up too without sheilds in the PF. The ground pins at the patch bay can be bussed together to form a global ground and tied to some convenient ground point, eg, the console chassis.

The only time this arrangement will come unstuck is if any equipment does not have a mains earth, ie, has a 2 wire power cord or has an external power supply adaptor (like some keyboards, domestic cd players etc....) In these cases, I would tie the sheild at the patch bay to the global ground mentioned above.

Which ever way you do it, plan it on paper (or in a spreadsheet) before you begin.

Good luck with it and happy soldering - I can smell the fumes from here!
Tim
Old 27th September 2006
  #8
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hi
With so much RF generating gear about these days I would suggest earthing both ends. If you then have any problems you can snip earths (on audio cables NOT MAINS) to sort out hums although I rarely find any with proper balanced gear with a decent grounding system.
Matt S
Old 28th September 2006
  #9
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Quote:
Originally Posted by Peter Morrison View Post
ok, I am trying to follow this.
Connect all shields at the patchbay- got this one
include a "looping ground" - so on normaled patches I should solder a ground from the ground on the upped jack to the ground on the lower?
cutting shields at every balanced input - so I should float the grounds at the inputs going in to outboard, mixers, converters, whatever (except mic ins for phantom reasons)

if you have a picture of one of your properly wired patchbay I would love you forever, in the gearsluttiest way

thanks
Peter

so on normaled patches I should solder a ground from the ground on the upper jack to the ground on the lower?
YES

cutting shields at every balanced input - so I should float the grounds at the inputs going in to outboard, mixers, converters, whatever (except mic ins for phantom reasons) YES

Reading this thread, it will be obvious that engineers have very different methods of wiring studios. I guess we have developed our own trusted systems and when an install comes up there is so much on the line that we're not very interested in experimenting with other ways.

Tim's system of lifting all grounds at the patchbay must be working fine for him. Two downsides come to mind. 1, one's options on the cable end are somewhat reduced. If you decide that you need the ground to be continuous through the bay and out to the gear, you'd have to go in and modify your work at the bay. 2, a console that has its own patchbay will probably not be wired this way, and one might would be forced to lift (some) shields on the gear end after all -- and now your installs are wired with two very different schemes, which would bother me. But hey, different strokes etc.

Attached are two photos of a bay we happen to be building this week. In the close up shot you can see the jumper wires for the half normal -- they're wired to T R S on the top, and TN RN S on the bottom.

OP, I wouldn't worry just yet about the unbalanced stuff in your system. My main concern would be the synths -- the unbalanced outs, in combination with sometimes questionable build quality, can cause ground noise. SOme mixers are more sensitive to this than others. Try it and see what happens. If the system is basically quiet with the exception of the synths, then you might consider balancing them.
Attached Thumbnails
Wiring up my bantam patch - earths and encouragement needed!-100_0127a.jpg  
Old 28th September 2006
  #10
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Photo #2:
Attached Thumbnails
Wiring up my bantam patch - earths and encouragement needed!-100_0129b.jpg  
Old 28th September 2006
  #11
Gear Head
 

I understand the reasons for alot of these practices, I think, but what is the reason to tie all grounds together with busswire at the patch bay and then run a wire to the console ground?? It would seem that if you simply lift on input, except on mic pre's, you would get rid of potential ground current paths and this kind of thing wouldn't be needed. Reasons anyone??? does this force some sort of star ground scheme even if your power isn't star ground? I have a patchbay that all grounds are common just by the construction and has connection to send a ground wire to your central ground, but others are made of a non-conductive material and jacks are isolated from eachother.

by the way a great thing to read is "solutions for hum, noise and interfefence" by Bill Whitlock of Jensen transformers.... a great lecture to see as well.

Thanks,

Jesse
Old 28th September 2006
  #12
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Quote:
Originally Posted by phalaris View Post
I understand the reasons for alot of these practices, I think, but what is the reason to tie all grounds together with busswire at the patch bay and then run a wire to the console ground?? It would seem that if you simply lift on input, except on mic pre's, you would get rid of potential ground current paths and this kind of thing wouldn't be needed. Reasons anyone??? does this force some sort of star ground scheme even if your power isn't star ground? I have a patchbay that all grounds are common just by the construction and has connection to send a ground wire to your central ground, but others are made of a non-conductive material and jacks are isolated from each other.

by the way a great thing to read is "solutions for hum, noise and interfefence" by Bill Whitlock of Jensen transformers.... a great lecture to see as well.

Thanks,

Jesse
Ugh, ground bussing methods are strongly discouraged. In audio we want to avoid instances of ground current passing through a shield or audio conductor. That's why I'm so bullish on telescoping shields with balanced gear. If you do this religiously, you eliminate 90% of possible ground noise issues right at the source, before they even start.

Bussing grounds has the exact opposite effect. Doing it results in a virtual spiderweb of ground interconnections -- the ground of every piece of gear is connected to the ground of every other piece.

Due to anomalies in power supplies and AC cabling, there will always be slight voltage differences between the grounds of different pieces of gear. Connect a ground wire between two pieces, ground noise current will flow through that wire. If the wire happens to be part of an audio connection, some amount of ground noise will likely be superimposed on the audio signal. Connect 100 grounds together and you have what -- almost 5000 possible combinations of grounding paths? It's a little like taking 100 people who all hate each other, and locking them inside one room. Chances are, there's going to be some noise!

In some problem situations, grounding everything in sight can reduce noise, but this is a band aid approach, and it rarely works perfectly. It's better to break the loop, and eliminate the unwanted ground currents. Isolate them, separate them.

Star grounding means that all grounds theoretically fan out from some central point, and don't connect to each other anywhere else. It's a neat concept but in the real world, very difficult to execute. Word clock cables, computer connections, AC strips, rack rails and other nasty details tend to undo the concept. In the old days of analog, balanced, audio only studios with big consoles it could be done faithfully, but if you have a studio with an Icon or a Procontrol and a batch of balanced, unbalanced, and computer gear, a true star system is nearly impossible to pull off. It doesn't matter -- good systems have been described on this thread and they can work well.
Old 28th September 2006
  #13
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7 Hz's Avatar
All the above complications and contrary ideas was the reason I started to consider that a PB with fully switched earths would be the way to go. At least then, all my earths could follow the signal, and I could then deal with lifting earths as needed at the equipment end.

It kinda struck me that the common / unswitched earth system on most PB's is a compromise, and may well be a throwback to the old telephone switchboards!

After saying this, I can't find a switched earth bantam patchbay in Mosses and Mitchell or ADC product lines :-(
Old 28th September 2006
  #14
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7 Hz's Avatar
Here is a cable layout diagram I did for my own benefit - it will be helpfull?
Attached Thumbnails
Wiring up my bantam patch - earths and encouragement needed!-studio-layout-cables-summ.gif  
Old 28th September 2006
  #15
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Hi
You could get M+M jacks with auxiliary contacts. You would wire the earth through this extra switch. Properly balance everything and have no earths except the mains? Life is a compromise.
Matt S
Old 29th September 2006
  #16
Gear Head
 
gjuodenas's Avatar
 

A studio's grounding scheme should start with a good electrical foundation. If possible, I would recommend the following.

First: Get your power company to make a survey of the power transformer on the pole that feeds your studio. Make sure the transformer is not overloaded. I have found many times that the power company keeps attaching service to the pole without upgrading the transformer resulting in some funky AC waveforms during peak usage times. They give themselves leeway by allowing say up to 120% capacity load.

Second: Get an isolation transformer that is large enough to supply all of your studio's equipment with some extra headroom for the future or for other gear to be brought in and out. A transformer with line conditiong capabilities like the SOLA product is ideal. It will keep the AC voltage at the proper level through most "brownouts" and will shape the waveform.

Third: Run a ground line from the secondary of the transformer to outside and drive in 3 ground rods in a triangle. Near a downdrain of your gutter system is a good location. The extra moisture helps create a good "connection" to ground. This ground becomes your safetry ground (3rd pin) and your neutral ground of your studio's outlets.

Fourth: Then home run your studio's outlets, do not string outlets in series. Your tech power outlets should be designated with a colored outlet. You could use orange outlets. Plug all equipment and instruments into tech power outlets only. This has to be strictly enforced.

Fifth: Run all ground lugs on equipment such as consoles separately to the exterior ground you established. You can have a buss point inside near the transformer if your cable to the ground rods is large enough.

At this point, you are ready to launch into a discussion of the shields and ground wires of your signal cables. I have a saying that I have been using for years POWER POWER POWER. All problems eventually lead back to this in some form. Usually if a chip or a transistor goes bad you have DC from the power supply showing up where it isn't supposed to be. Random noises can often be traced to "dirty power". I could go on and on. The moral is, set up as solid an electrical and ground system for your studio as you can. Do not skimp!
Old 29th September 2006
  #17
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Hi
The above sounds pretty reasonable but I don't think that the safety issue is quite fully covered. The SECONDARY of the transformer should have an earth leakage breaker fitted (this senses differences between 'live' and 'neutral' and assumes that if there is a difference of more than (30mA in the UK / Europe) then there is a fault so switch off fast. This needs the neutral to be grounded (as proposed above) or if possible a centre tap an the secondary of the transformer should be taken to the ground spikes (and the incoming earth). This would provide balanced power, which is claimed (and probably true) REALLY helps with preventing hums.
I am not sure however if you are allowed to do this with regard to legality as it is probably not a 'power company' approved installation. Assuming a RCCD will trip as intended there is no technical reason why this is unsafe. In a commercial studio you may need some form of approval or insurance notification.
Matt S
Old 29th September 2006
  #18
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7 Hz's Avatar
gjuodenas and Matt Syson - thanks for that info, but it is outside the scope of my question and also my physical space (I am in a 2nd floor flat in a city, so I can't start banging 6 foot copper poles into the ground and running thick earth straps to them).

Although I appreciate that solid mains earthing is very important, I am only interested in the patchbay wiring of earths ATM.

As it stands just now, the equipment is set up and hard wired straight to the desk. There is no issues of hum apart from my Sequential Pro-One, and I suspect this is an internal issue with PSU caps or just design.

What I am interested in doing is wiring up a Bantam patchbay in a way that I don't introduce any issues into this already working system.

Cheers!
Old 29th September 2006
  #19
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7 Hz's Avatar
Quote:
Originally Posted by Matt Syson View Post
Hi
You could get M+M jacks with auxiliary contacts. You would wire the earth through this extra switch. Properly balance everything and have no earths except the mains? Life is a compromise.
Matt S
Thats Moses and Mitchell? I don't see those listed on their site.

I can accept compromise, but only if it is the best compromise I can think of / afford!
Old 29th September 2006
  #20
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Hi
Yes Mosses and Mitchell. I am working from memory and they would have been PO jacks not bantams although these may be available. I would expect an arm and at least two legs each in terms of cost.
Actually the sleves are not commoned on M+M patches (or similar makes) so the grounds would follow the wiring anyway. It is the normalling that would mess it up.
Copper rods on 2nd floor, have you guys got no sense of adventure? Go for it.
Matt S
Old 29th September 2006
  #21
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Geoff_T's Avatar
 

Quote:
Originally Posted by 7 Hz View Post
gjuodenas and Matt Syson - thanks for that info, but it is outside the scope of my question and also my physical space (I am in a 2nd floor flat in a city, so I can't start banging 6 foot copper poles into the ground and running thick earth straps to them).

Cheers!
Hi

If you are on the top of a skyscraper, you can still probably get a good ground by bonding to the main cold water feed pipe.

Old 29th September 2006
  #22
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firby's Avatar
 

Quote:
Originally Posted by Geoff_T View Post
Hi

If you are on the top of a skyscraper, you can still probably get a good ground by bonding to the main cold water feed pipe.

If it is a commercial space this is illegal in some places.

Works good though !
Old 29th September 2006
  #23
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7 Hz's Avatar
Well I think my pipes are bonded to earth, but the central pipe is lead, so it's not gonna work as a ground.

I think my ground is OK here in any case, what I am worried about is the grounding on the signal side of my line level music gear when I go to rewire everything with a bantam patchbay in the middle.
Old 29th September 2006
  #24
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Hi
A conductor (waterpipe or cables) mounted vertically or any fancy angle constitutes an aerial.
Your studio is at the 'hot' end compared to ground.
There is no 'absolute best' way to do the grounding (patch) but most places get by.
Matt S
Old 29th September 2006
  #25
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Geoff_T's Avatar
 

Quote:
Originally Posted by 7 Hz View Post
Well I think my pipes are bonded to earth, but the central pipe is lead, so it's not gonna work as a ground.
Hi

Yikes, you're kidding?

Why is everyone fluffing around with ROHS when you are drinking lead polluted water?

Old 30th September 2006
  #26
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7 Hz's Avatar
Yup, real lead pipes! Makes the water nice and sweet, I don't see the problem
Old 30th September 2006
  #27
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Geoff_T's Avatar
 

Quote:
Originally Posted by 7 Hz View Post
Yup, real lead pipes! Makes the water nice and sweet, I don't see the problem
Hi

Many decades ago when I rewired my mother's home (to IEE specs and approved by the local electricity inspectors) the incoming supply cable from the street was lead encased and the ground to the house was taken from a clamp around this lead casing. It was also bonded to the incoming water pipework.

Lead can't be that bad a conductor... there has been around 60% lead in solder for aeons.

Old 30th September 2006
  #28
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Hi
I have a book that details various methods of wiring. One is to use bare conductors inside wooden chanelling. It also included DC mains supplies and the use of 'knife' switches for circuit isolation. One of the methods of connecting wires together was a 'married joint' now that could be taken many ways!!
All miles away from topic.
Matt S
Old 30th September 2006
  #29
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Geoff_T's Avatar
 

Quote:
Originally Posted by Matt Syson View Post
Hi
I have a book that details various methods of wiring. One is to use bare conductors inside wooden chanelling. It also included DC mains supplies and the use of 'knife' switches for circuit isolation. One of the methods of connecting wires together was a 'married joint' now that could be taken many ways!!
All miles away from topic.
Matt S
Hi Matt

Also miles away from topic....

One of the spin offs of "losing a war" is that new factories are built with new equipment, etc.

I started work in a company that still had pre war electrical test panels. I look back on it with amazement that I survived. We had motor generator sets to create 660 volts dc (as used for London Underground equipment) and also lethal mobile transformers that could crank out up to around 33KV. We also had a giant motor generator that could generate a 35MVA fault current.

It had a concrete floor and wall panels with exposed wiring and knife switches. If a test engineer was checking a reading on his AVO 7 and not looking where he put his hand... they sometimes touched the metal part of the 660v dc knife isolating switch.

In those circumstances, as the guy sunk gibbering towards the floor, was to get back a few yards for a good run and charge at him so that the impetus of the collision knocked him off the switch. Otherwise you'd get a shock off him, etc.

We also had a mechanical shock testing machine as we built switch gear for the Navy. It consisted of a two inch or so thick steel panel that was struck by a huge hammer like a giant pendulum. The rectangular weight at the end probably weighed 1/4 ton.

You put the switch gear on the plate, switched it on, then winched this damn great pendulum backwards around 45 degrees or more. The snag was that the release rope was under the arc of the pendulum so you had to stand between its path and the plate, yank the rope, then dive backwards.

If you didn't move quick enough, a high speed cine camera monitoring the effects of the shock would capture the messy conclusion!

Old 30th September 2006
  #30
Gear Head
 
gjuodenas's Avatar
 

Boy we have gotten off topic but:

The pendulum striking a steel plate brought back some memories. When I first started in audio, I worked for a company that got a contract to design an external (outside in the environment) loudspeaker for a Navy battleship. One of the requirements was that it had to survive the pressure wave from an explosion (I said say what?) and keep on working, it also had to survive impact tests and environmental tests. The impact test was conducted by clamping the loudspeaker to a large steel plate and then hitting the plate with a large steel ball on a pendulum from behind. I got to the point where I looked forward to the speaker launching off of the plate in many pieces. I was totally grossed out by seeing the loudspeaker after it had spent time in an environmental test chamber, it had all colors of mold growing on it. It actually performed the best in the pressure wave from an explosion test.
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