Agilent 1670G - I Killed it - Opinions

[CoalCreekPlastics]

Hi all,  I hate that this is my first post (I need to be in the beginner section) but I had scored a reasonably priced Agilent 1670g logic analyzer, intending to get into FPGA's and microcontrollers.  I was running through some self-tests last night and everything was passing and "worked a treat," when I noticed the fans were dusty.  Well me being me, I decided a shot of compressed air couldn't hurt, so while the unit was powered on I shot a a short blast into the power supply fan.  I saw a spark, heard a loud pop and smelled burning and got a little bit of the magic smoke and the unit powered off. 

Did my shooting compressed air in that fan really kill the PS? 

I could return the unit, it has a "90 day warranty" but if I am responsible and it has a possibility of being repairable I don't necessarily want to do that, it was a great price.

Should I try to repair that power supply?  How difficult is that for a beginner that has an aversion to electrocution, is reasonable well equipped and can solder?  The power supply is Agilent part number 0950-3403 which is a Celestica 5011-eaac00-111 500 watt power supply.  Have not yet found any schematics for it.  The only replacement I have found was one for $299 asking price on eBay.  That's more than I paid for the analyzer.

I'm hoping it's just a fuse and a burned up fan but Murphy looms large here.  I planned to take it apart tonight to get the supply out.  I appreciate any input you folks might offer.  Thanks in advance for your time an input.

[helius]

I can see several possible consequences.
1. By forcing air into the fan, you turned the fan motor into a generator and caused a surge on the power rail.
2. The "compressed air" was actually fluoroethylene and it ignited.
3. It cooled the electronics suddenly, which either fractured a component through freezing, or else caused a step change in electrical resistance leading to rapid power consumption.

Clearly more went wrong than just a fuse, but the smoke could have come from a fusible resistor, and repair may be straightforward.

[abraxa]

My gut feeling tells me that the magic smoke wasn't merely the fluoroethylene burning some dust but some electronics dying instead. If you like it so much and bought it for cheap then I'd keep it around instead of returning it. Either you can fix it now after looking at the power supply or you can fix it later, when you gained more experience and don't feel shy around line voltage anymore.

What you did falls into the "lesson learned, will never ever do again" category of mistakes. We all have some of those on our belts

[alm]

Most people here will know the sinking feeling of having destroyed something expensive due to a brief moment of stupidity. I certainly do.

A loud pop does not really sound like just a fuse to me. A warranty claim does not seem fair to me (since this is 95% likely your fault, like making a warranty claim after dropping something and smashing it). How is the availability of service documentation? It may have basic troubleshooting steps like measuring power supply voltages to determine if the power supply is faulty, for example the recommended load resistors to apply if running the power supply unplugged from the logic analyzer. Probably no component-level information like schematics. If you power it up again, watch for more smoke or strange noises, and in that case power if off immediately and switch to a visual inspection.

As a beginner, I would not do any measurements on the off-line switch mode power supply with the mains power applied. Wear safety glasses when powering it up without its case (or close the case before powering up). Make sure it is unplugged from mains and all caps are discharged before you touch it (especially the primary ~320 VDC filter capacitor can be nasty). I would look for obviously burnt components, burnt traces or semiconductors with a hole blown into them (blow hole). If you are lucky, it may work again after replacing damaged part(s) and or repairing damaged traces. If you are not so lucky, it might blow up the parts again after you power it up .

Since you live in the US where shipping may cost less than the price of the unit, you could keep your eyes peeled for a cheap parts unit with a likely working power supply (e.g. powers up, but self test reports errors).

[CoalCreekPlastics]

So I did a quickie lookup of the MSDS on the Ultraduster that I used:

SECTION I - CHEMICAL INFORMATION
Trade Name: HFC-152a
Chemical Name: Difluoroethane, R152a
Product Supplied By: AW Distributing, Inc.
Address & Phone #: 2024 Middlefield Rd., Redwood City, CA 94063

These are sold in Wal-Mart stores so not sure if that's flammable.  It didn't feel like a detonation, just a nice crisp spark/pop and yeah some component burned up, I could smell it.  I didn't get any of the "freeze" effect you get from those kind of dusters.  Can't speak in absolutes of course.

I hope the power supply will give up it's secrets and not the ghost when I pull it later.  I'll post pics this could be a good case for other newbies like me.  I guess you could say I screwed up proper.

Yeah definitely will never do it again, I feel like an idiot.  That's what happens when you let line-of-business software guys around the electronics. 

[CoalCreekPlastics]

Most people here will know the sinking feeling of having destroyed something expensive due to a brief moment of stupidity. I certainly do.

A loud pop does not really sound like just a fuse to me. A warranty claim does not seem fair to me (since this is 95% likely your fault, like making a warranty claim after dropping something and smashing it). How is the availability of service documentation? It may have basic troubleshooting steps like measuring power supply voltages to determine if the power supply is faulty, for example the recommended load resistors to apply if running the power supply unplugged from the logic analyzer. Probably no component-level information like schematics. If you power it up again, watch for more smoke or strange noises, and in that case power if off immediately and switch to a visual inspection.

As a beginner, I would not do any measurements on the off-line switch mode power supply with the mains power applied. Wear safety glasses when powering it up without its case (or close the case before powering up). Make sure it is unplugged from mains and all caps are discharged before you touch it (especially the primary ~320 VDC filter capacitor can be nasty). I would look for obviously burnt components, burnt traces or semiconductors with a hole blown into them (blow hole). If you are lucky, it may work again after replacing damaged part(s) and or repairing damaged traces. If you are not so lucky, it might blow up the parts again after you power it up .

Since you live in the US where shipping may cost less than the price of the unit, you could keep your eyes peeled for a cheap parts unit with a likely working power supply (e.g. powers up, but self test reports errors).

I agree wholeheartedly with you alm on the ethical issue of returning.  I just put that out there in case what I did was harmless and there was another issue that this just facilitated.  It appears that is not the case and this is in fact due to my stupidity.  So let's take the return idea off the table.  I want this unit working again.

There is a service manual with instructions on how to test the power supply, and I will follow your common sense guidance.

[abraxa]

I hope the power supply will give up it's secrets and not the ghost when I pull it later.  I'll post pics this could be a good case for other newbies like me.

Please do upload pictures of the power supply after you give it enough time to discharge after pulling the plug (30 minutes should be enough but you never know, so best to treat it as if it were live). Maybe it's something that's obvious to one of us, like a cracked diode.

[WastelandTek]

Well, OP, we learned a lesson today didn't we?

I wasn't going to wade into this thread, but you won me over with your, increasingly uncommon it seems, sense of honor regarding returning the unit.

Do open it up and "have a squizz"  Some well lit macro shots of the circuit boards would help us a lot.

[CoalCreekPlastics]

Well, OP, we learned a lesson today didn't we?

I wasn't going to wade into this thread, but you won me over with your, increasingly uncommon it seems, sense of honor regarding returning the unit.

Do open it up and "have a squizz"  Some well lit macro shots of the circuit boards would help us a lot.

That's kind of you to jump in.  Thanks.  Boy howdy did I learn a lesson.  In retrospect I don't know what I was thinking.  Good thing it wasn't a much more expensive piece of equipment and it didn't belong to an employer or someone else!

I did "have a squizz" and it's a pretty dense arrangement so I'm going to need to de-solder a daughterboard that's at right angle to the main board (see on the left in the photo.)  I'll re-shoot some good photos with the Andostar, the ones I got with the iPhone were too big to post and didn't show enough.

I did smell something singed.

More to come.

ETA: Any advice on which side to de-solder that connection from, the bottom of the main board or at the daughterboard connection?

[Specmaster]

What is that brown gooey mess in the top left corner of the photo? Looks like a cap may have blown and shot its electrolyte out.

On the topic of returning it, I believe that you could have done and feel justified in doing so. I find it really hard to believe that giving it a shot of compressed air from a can would do that, especially given that the fan was running, unless you held the can upside down it is extremely unlikely that any liquid "freeze spray" shot into the fan and even then the blades would be chopping this up into a fine mist anyway.

I think it was a coincidence that it happened while you were spraying it. Its a strong possibility that either a smoothing electrolytic cap has decided to let go or a mains filter / suppression cap has blown and in so doing the arc has blown the fuse.

[cncjerry]

I think the air blowing was coincidence unless you blew some conducting material in there.  I have to be careful around my metal working machines with compressed air for that reason.  I think a cap or something in the power supply let go coincidental to the air.

You need to find the part that blew and we can tell you the odds of repair.

Jerry

[tablatronix]

Does your spray say non conductive?

[amyk]

So I did a quickie lookup of the MSDS on the Ultraduster that I used:

SECTION I - CHEMICAL INFORMATION
Trade Name: HFC-152a
Chemical Name: Difluoroethane, R152a
Product Supplied By: AW Distributing, Inc.
Address & Phone #: 2024 Middlefield Rd., Redwood City, CA 94063

These are sold in Wal-Mart stores so not sure if that's flammable.  It didn't feel like a detonation, just a nice crisp spark/pop and yeah some component burned up, I could smell it.  I didn't get any of the "freeze" effect you get from those kind of dusters.  Can't speak in absolutes of course.

I hope the power supply will give up it's secrets and not the ghost when I pull it later.  I'll post pics this could be a good case for other newbies like me.  I guess you could say I screwed up proper.

Yeah definitely will never do it again, I feel like an idiot.  That's what happens when you let line-of-business software guys around the electronics. 

That's a hydrofluorocarbon. Yes, it's flammable. (The old fluoro/chlorocarbons were not, but the environmentalists didn't like the effects they had on the environment...)

[cncjerry]

I blew 'dustbuster' into a cooktop once to clear out a clogged gas igniter hole.  Big mistake as it exploded and I inhaled the flames.  I often wondered if God knew that causing us to inhale when surprised was a good idea?  Flames?  Cold water?  Ha!

But I learned my lesson with the stuff. 

We need to see what blew.  Take more pictures.

[CoalCreekPlastics]

What is that brown gooey mess in the top left corner of the photo? Looks like a cap may have blown and shot its electrolyte out.

On the topic of returning it, I believe that you could have done and feel justified in doing so. I find it really hard to believe that giving it a shot of compressed air from a can would do that, especially given that the fan was running, unless you held the can upside down it is extremely unlikely that any liquid "freeze spray" shot into the fan and even then the blades would be chopping this up into a fine mist anyway.

I think it was a coincidence that it happened while you were spraying it. Its a strong possibility that either a smoothing electrolytic cap has decided to let go or a mains filter / suppression cap has blown and in so doing the arc has blown the fuse.

I thought that was some adhesive/buffer material used in-between components.  There are several deposits of it around the board.

I can't find an obvious fuse...

[CoalCreekPlastics]

I blew 'dustbuster' into a cooktop once to clear out a clogged gas igniter hole.  Big mistake as it exploded and I inhaled the flames.  I often wondered if God knew that causing us to inhale when surprised was a good idea?  Flames?  Cold water?  Ha!

But I learned my lesson with the stuff. 

We need to see what blew.  Take more pictures.

Wow!  Good to know.  More pictures are the plan tomorrow!

[abraxa]

I did "have a squizz" and it's a pretty dense arrangement so I'm going to need to de-solder a daughterboard that's at right angle to the main board (see on the left in the photo.)  I'll re-shoot some good photos with the Andostar, the ones I got with the iPhone were too big to post and didn't show
ETA: Any advice on which side to de-solder that connection from, the bottom of the main board or at the daughterboard connection?

Removing the daughterboard from the PSU for maintenance of the unit seems a really time-consuming (and not straightforward) thing to do, so my guess is that there's something you must be overlooking to get the entire assembly out, including the daughterboard.

[CJay]

What is that brown gooey mess in the top left corner of the photo? Looks like a cap may have blown and shot its electrolyte out.

On the topic of returning it, I believe that you could have done and feel justified in doing so. I find it really hard to believe that giving it a shot of compressed air from a can would do that, especially given that the fan was running, unless you held the can upside down it is extremely unlikely that any liquid "freeze spray" shot into the fan and even then the blades would be chopping this up into a fine mist anyway.

I think it was a coincidence that it happened while you were spraying it. Its a strong possibility that either a smoothing electrolytic cap has decided to let go or a mains filter / suppression cap has blown and in so doing the arc has blown the fuse.

I thought that was some adhesive/buffer material used in-between components.  There are several deposits of it around the board.

I can't find an obvious fuse...

Yes, that brown stuff is some sort of adhesive, not the guts of a cap.

No, spinning the fan with freeze spray would not cause 'a surge on a power rail' that's just nonsense.

it's possible you've cooled some component enough to throw the PWM out of toleracne and made an expensive bang, it's also possible you've got it cold enough to cause condensation then it could be absolutely anything in there.

There will be a fuse, it may be wire ended and covered in heatshrink.

You need to check for shorts on the power devices and input filter as a first point of action, that will give you a rough idea of how much damage you're looking at.

We need more pics of the board, both sides, several angles on the component sides.

[Towger]

Bottom right of the photo appears to show my least favourite mains suppression capacitor.  Check it for cracks in the clear epoxy case.

[oldway]

I would like to take advantage of the subject to tell you what happened to me when I was doing the maintenance of industrial no breaks.

I was blowing the dust from the radiators of the power semiconductors with a jet of compressed air coming from a Nilfisk blower motor.
I was doing this with No-break in operation.

One day I was doing this operation on a no-break of 10KVA and 120V battery voltage.
I saw something flying in the no-break.
I immediately stopped the dusting and looked at what it was : It was an aluminum chocolate packaging  ....

How has it been  there, I don't know...

I had a little retrospective fear because if this aluminum packaging had touched a power circuit, it could have caused a serious accident.

Since then, I desenergize the No-break completely before blowing the radiators. 

[IanMacdonald]

I think the most likely scenario, as mentioned, is that there was a foreign object in there already and your air blast moved it into contact with a live part.

As to repair, depends what damage it's done. You might be lucky and find it's just blown the internal fuse. Bear in mind that If it's taken out the switching transistor(s) it may also have taken out any current sensing resistors in series with these.  Or. driver ICs.

Testing a SMPS generally involves having an (earth-free) isolating transformer and some form of current limiting device. A household bulb will do at a pinch though a variac is better. One thing is certain though, if you replace blown components and test at full voltage but have missed one.. BANG and you start all over again. Thus, a current limiter of some kind is more or less a must for testing.

[CoalCreekPlastics]

I think the most likely scenario, as mentioned, is that there was a foreign object in there already and your air blast moved it into contact with a live part.

As to repair, depends what damage it's done. You might be lucky and find it's just blown the internal fuse. Bear in mind that If it's taken out the switching transistor(s) it may also have taken out any current sensing resistors in series with these.  Or. driver ICs.

Testing a SMPS generally involves having an (earth-free) isolating transformer and some form of current limiting device. A household bulb will do at a pinch though a variac is better. One thing is certain though, if you replace blown components and test at full voltage but have missed one.. BANG and you start all over again. Thus, a current limiter of some kind is more or less a must for testing.

You know I'm really thinking you and the others that suggest a foreign object may be right.  The spark was directly at the terminal connection on the fan side, and it was a short puff of air.  No "freeze juice" came out (you know with the canned air sometimes you get the propellant or whatever that freezes the thing you're dusting"  frozen components just didn't happen here.  I'm questioning if the fan was manipulated enough to cause a charge like that.

After sleeping on this another night, I really just don't think I have the experience to troubleshoot this.  I am still working on the fundamentals.  Power supply with mains voltage just isn't something I am comfortable doing yet.

[WastelandTek]

Are you, by chance, located in King County?

[Specmaster]

I think the most likely scenario, as mentioned, is that there was a foreign object in there already and your air blast moved it into contact with a live part.

As to repair, depends what damage it's done. You might be lucky and find it's just blown the internal fuse. Bear in mind that If it's taken out the switching transistor(s) it may also have taken out any current sensing resistors in series with these.  Or. driver ICs.

Testing a SMPS generally involves having an (earth-free) isolating transformer and some form of current limiting device. A household bulb will do at a pinch though a variac is better. One thing is certain though, if you replace blown components and test at full voltage but have missed one.. BANG and you start all over again. Thus, a current limiter of some kind is more or less a must for testing.

You know I'm really thinking you and the others that suggest a foreign object may be right.  The spark was directly at the terminal connection on the fan side, and it was a short puff of air.  No "freeze juice" came out (you know with the canned air sometimes you get the propellant or whatever that freezes the thing you're dusting"  frozen components just didn't happen here.  I'm questioning if the fan was manipulated enough to cause a charge like that.

After sleeping on this another night, I really just don't think I have the experience to troubleshoot this.  I am still working on the fundamentals.  Power supply with mains voltage just isn't something I am comfortable doing yet.

Then on that basis I would look at returning it for a refund as I really find it too mind boggling to think that you may have blown some foreign object into it, it would still have to get past the spinning fan blades which would be even greater odds than having the winning ticket for the lottery. Personally I'd say it was a fluke that whatever happened, happened at the same time as you spraying compressed air into the fan. I'd be inclined to tell the seller that it just went bang on powering it up and  say nothing else.

[rsjsouza]

I also imagine it was a foreign object violently blown into the equipment. In the past I have seen many fan assemblies with tiny specs of metallic material ingrained into the heavily thick dust - especially on its protection grid. The fan itself did not have enough air pressure to blow them, but a spray could easily do that.

Given there was smoke and the "Ampère smell", I would carefully inspect the circuit that could be in the path of the fan assembly airflow. Pay special attention to tiny cracked transistors (especially the large ones mounted on the heatsink) and diodes - short circuits would have a tendency to blow these first.

As others have said regarding the spray can itself, just keep in mind what kids use to make blowtorches...