Author Topic: EEVblog #405 - Lecroy 9384C Oscilloscope Repair - Part 3  (Read 27101 times)

0 Members and 1 Guest are viewing this topic.

Offline EEVblogTopic starter

  • Administrator
  • *****
  • Posts: 39277
  • Country: au
    • EEVblog
EEVblog #405 - Lecroy 9384C Oscilloscope Repair - Part 3
« on: December 30, 2012, 07:52:44 am »


Dave.
 

Offline Pentium100

  • Frequent Contributor
  • **
  • Posts: 258
  • Country: lt
Re: EEVblog #405 - Lecroy 9384C Oscilloscope Repair - Part 3
« Reply #1 on: December 30, 2012, 08:30:54 am »
Something being "worth" depends a lot on how much money one has. I for example repair broken ATX power supplies, because this lets me save a little bit of money (and since I replace the caps with good quality ones the repaired power supply will probably last longer than a new one).

Actually, I try to repair everything before giving up and buying a new device. If I can do it, I save some money (because the replacement parts do not cost as much as the new device).

That scope maybe has protection against bad power supply - without 4 rails the CPU might not have displayed anything at all. Or the power to the CRT may be provided by one of the dead rails.
 

Offline peter.mitchell

  • Super Contributor
  • ***
  • Posts: 1567
  • Country: au
Re: EEVblog #405 - Lecroy 9384C Oscilloscope Repair - Part 3
« Reply #2 on: December 30, 2012, 08:42:11 am »
This video makes me sad, it's odd, I had a pet dog (it was in a state of ill health, 17 years old) put down earlier this week and it didn't make me feel this sad :S Dammit weird electronics people :(
 

Offline justanothercanuck

  • Frequent Contributor
  • **
  • Posts: 391
  • Country: ca
  • Doing retro repairs...
Re: EEVblog #405 - Lecroy 9384C Oscilloscope Repair - Part 3
« Reply #3 on: December 30, 2012, 08:46:40 am »
It's kindof a downer that it's dead, but if it's dead, what can you do?  It's too bad pumping several amps into it doesn't set the thing on fire...  ;D
Maintain your old electronics!  If you don't preserve it, it could be lost forever!
 

Offline JoannaK

  • Frequent Contributor
  • **
  • Posts: 336
  • Country: fi
    • Diytao making blog
Re: EEVblog #405 - Lecroy 9384C Oscilloscope Repair - Part 3
« Reply #4 on: December 30, 2012, 08:47:27 am »
Ah well.. Sometimes it just happen.  :-BROKE
 

Offline firewalker

  • Super Contributor
  • ***
  • Posts: 2454
  • Country: gr
Re: EEVblog #405 - Lecroy 9384C Oscilloscope Repair - Part 3
« Reply #5 on: December 30, 2012, 09:08:09 am »
Just juice it up with 40 amps!  ;D ;D ;D

Alexander.
Become a realist, stay a dreamer.

 

Offline ftransform

  • Frequent Contributor
  • **
  • Posts: 728
  • Country: 00
Re: EEVblog #405 - Lecroy 9384C Oscilloscope Repair - Part 3
« Reply #6 on: December 30, 2012, 09:24:20 am »
send it to photonic induction
 

Offline Ketturi

  • Regular Contributor
  • *
  • Posts: 68
  • Country: fi
    • Ketturi Electronics
Re: EEVblog #405 - Lecroy 9384C Oscilloscope Repair - Part 3
« Reply #7 on: December 30, 2012, 10:12:33 am »
Even greatest people can't always succeed. Especially in electronics, where n+1 things can go wrong. Sad to see that scope is hopelessly dead, but there wasn't really high expectation after 1st or 2nd video. But hey, now Dave have time to something better, maybe it is just good that this thing is left rest in peace.

Btw, I would my self take that CRT display and it's circuitry and try to reverse-engineer it, I love those old amber/green mono displays, and actually I have one working unit under my nightstand xD
Ketturi electronics: http://ketturi.kapsi.fi
 

Offline SeanB

  • Super Contributor
  • ***
  • Posts: 16386
  • Country: za
Re: EEVblog #405 - Lecroy 9384C Oscilloscope Repair - Part 3
« Reply #8 on: December 30, 2012, 10:16:31 am »
Better to lift it with the Quadcopter and release it from a height, at least it will make for a nice bang...........
 

Offline obsoletemac

  • Newbie
  • Posts: 7
Re: EEVblog #405 - Lecroy 9384C Oscilloscope Repair - Part 3
« Reply #9 on: December 30, 2012, 11:45:27 am »
Hi (My first post  :D )
Would it be possible to get that little heatsink off to see what that ASIC-ish IC is?

//c
 

Offline RoelA

  • Contributor
  • Posts: 10
Re: EEVblog #405 - Lecroy 9384C Oscilloscope Repair - Part 3
« Reply #10 on: December 30, 2012, 11:57:21 am »
@obsoletemac , Dave said that it would be very hard and you need chemicals that he doesn't have to remove the glue / thermal stuff..

Probably easier just to look it up in the schematics in the other thread :)
 

Offline SeanB

  • Super Contributor
  • ***
  • Posts: 16386
  • Country: za
Re: EEVblog #405 - Lecroy 9384C Oscilloscope Repair - Part 3
« Reply #11 on: December 30, 2012, 12:07:10 pm »
Now it is off you just use a heat gun and cook till well done ( and a little smoky as well) then the chip will basically fall off the cooked epoxy.
 

Offline ftransform

  • Frequent Contributor
  • **
  • Posts: 728
  • Country: 00
Re: EEVblog #405 - Lecroy 9384C Oscilloscope Repair - Part 3
« Reply #12 on: December 30, 2012, 12:15:59 pm »
does anyone else think it might be the second asic? It did get 2 degrees hotter after all. :-+
 

Offline SeanB

  • Super Contributor
  • ***
  • Posts: 16386
  • Country: za
Re: EEVblog #405 - Lecroy 9384C Oscilloscope Repair - Part 3
« Reply #13 on: December 30, 2012, 12:22:17 pm »
Probably all 4 are CBB inside from the power supply failing and dumping the 5V rail onto the 3V3 rail before the internal fuse popped. I have seen many ATX supplied die this way, though generally the 5V line protection operates and kills the supply.
 

Offline CarlG

  • Regular Contributor
  • *
  • Posts: 155
  • Country: se
Re: EEVblog #405 - Lecroy 9384C Oscilloscope Repair - Part 3
« Reply #14 on: December 30, 2012, 12:43:24 pm »
@obsoletemac
@SeanB

As RoelA said: much easier to check the manual. At least for the one who does the job. Why ask Dave to do something that you might as well do yourself?

It's an MDX622 demultiplexer + peak detect monolithic IC

======================
Excuse me for being rude but please RTM
« Last Edit: December 30, 2012, 07:11:23 pm by CarlG »
 

Offline jancumps

  • Supporter
  • ****
  • Posts: 1273
  • Country: be
  • New Low
Re: EEVblog #405 - Lecroy 9384C Oscilloscope Repair - Part 3
« Reply #15 on: December 30, 2012, 12:49:29 pm »
Auction it for charity.
 

Offline Winston

  • Regular Contributor
  • *
  • Posts: 121
  • Country: us
    • IC Die Photography
Re: EEVblog #405 - Lecroy 9384C Oscilloscope Repair - Part 3
« Reply #16 on: December 30, 2012, 01:27:26 pm »
Yep, time to give up on this thing.  It is now officially a boat anchor.  If even one of the ASICs is bad, it is not economically worthwhile to repair.  The process of troubleshooting was very interesting though.
 

Offline tinhead

  • Super Contributor
  • ***
  • Posts: 1918
  • Country: 00
    • If you like my hacks, send me a donation
Re: EEVblog #405 - Lecroy 9384C Oscilloscope Repair - Part 3
« Reply #17 on: December 30, 2012, 01:42:24 pm »
Something being "worth" depends a lot on how much money one has.

hmm, i think you wrong. It depends on how much money you could get in the same time if you would
simply work during this time instead of "wasting for repair".

Each every "free" hour we have can be calculated back to money, each time you don't go to work
(because you wish to have your free time just because you wasted it before by doing your hobby)
you can count that money.

Of course not every have a job, or not everybody really care about the free time (e.g. while writing this
i wasted time anyway, so it could be sometimes to "use it" more useful instead of typing ugly long text)

Actually, I try to repair everything before giving up and buying a new device.

yeah, i still remember my Yokogawa Signal Gen repair. Due the moisture (actually i think it was cup of coffe and an idiot)
one of the PCBs was complettly broken and another one partially. I had to restore many digital and analog traces - and
parts as well. I got the Gen dirt cheap, so i spend only "time" and parts. Finally, after i counted only the parts i was
already over the "used gear" price, not funny eh. And of course, i spend a week!, to restore the PCB.
So finally i spend, with work hours and parts, about 3k USD. For that money i could nearly buy a new one.

But yeah, i does not means that i gived up and not repairing things anymore, sure i do it still. However
for most thigns - unless it's just really unique or really cool thing - i'm calculating the time and money i wish
to invest, and if i'm over the limit then i'm simply stopping (and selling such things for few bucks to compensate a bit).

In Dave's case, in ym opinion, he reached the limit already.

Auction it for charity.

yeah, good idea
I don't want to be human! I want to see gamma rays, I want to hear X-rays, and I want to smell dark matter ...
I want to reach out with something other than these prehensile paws and feel the solar wind of a supernova flowing over me.
 

Offline G7PSK

  • Super Contributor
  • ***
  • Posts: 3890
  • Country: gb
  • It is hot until proved not.
Re: EEVblog #405 - Lecroy 9384C Oscilloscope Repair - Part 3
« Reply #18 on: December 30, 2012, 01:53:18 pm »
Looks like the LeCroy is as dead as the Monty python parrot, time to take it out and give it a decent send off https://www.eevblog.com/forum/Smileys/default/smiliey_scope_broke.gif
 

Online IanJ

  • Supporter
  • ****
  • Posts: 1849
  • Country: scotland
  • Full time EE & Youtuber/Creator
    • IanJohnston.com
Re: EEVblog #405 - Lecroy 9384C Oscilloscope Repair - Part 3
« Reply #19 on: December 30, 2012, 06:01:31 pm »
Looks like the LeCroy is as dead as the Monty python parrot, time to take it out and give it a decent send off https://www.eevblog.com/forum/Smileys/default/smiliey_scope_broke.gif

Absolutely!..................Would love to see Dave set fire to the LeCroy.......it's job is done.

Ian.
Ian Johnston - Original designer of the PDVS2mini || Author of WinGPIB
Website: www.ianjohnston.com
YouTube: www.youtube.com/user/IanScottJohnston, Odysee: https://odysee.com/@IanScottJohnston, Twitter(X): https://twitter.com/IanSJohnston, Github: https://github.com/Ian-Johnston?tab=repositories
 

Offline ZekeD

  • Newbie
  • Posts: 3
Re: EEVblog #405 - Lecroy 9384C Oscilloscope Repair - Part 3
« Reply #20 on: December 30, 2012, 10:50:56 pm »
Thanks for the excellent troubleshooting, and proper evaluation on when to say enough is enough.

While the scope is beyond hope, the amount of knowledge passed on in the process made this a massive success. Happy new year.
 

Offline robrenz

  • Super Contributor
  • ***
  • Posts: 3035
  • Country: us
  • Real Machinist, Wannabe EE
Re: EEVblog #405 - Lecroy 9384C Oscilloscope Repair - Part 3
« Reply #21 on: December 30, 2012, 11:57:02 pm »
+1 :-+

Offline krenzo

  • Regular Contributor
  • *
  • Posts: 102
  • Country: us
Re: EEVblog #405 - Lecroy 9384C Oscilloscope Repair - Part 3
« Reply #22 on: December 31, 2012, 03:19:25 am »
I wish Dave would at least cut the 3 other chips off to show the short going away.
 

Offline McMonster

  • Frequent Contributor
  • **
  • Posts: 413
  • Country: pl
    • McMonster's blog
Re: EEVblog #405 - Lecroy 9384C Oscilloscope Repair - Part 3
« Reply #23 on: December 31, 2012, 03:30:30 am »
While I am curious about the real cause of the short and failure I also think we've had enough of this scope already. There's just nothing interesting more to do with it. Time for a different video.

Wel, actually there is something that could be interesting, but it would have to include destruction of the board, preferably photonicinduction style.
 

Offline gazza666

  • Newbie
  • Posts: 5
Re: EEVblog #405 - Lecroy 9384C Oscilloscope Repair - Part 3
« Reply #24 on: December 31, 2012, 09:30:47 am »
I would remove the other three ASIC-ish IC to see if the short was gone
the board would be nice and clean then in case somebody donated four new chips
you never know
 

Offline M. András

  • Super Contributor
  • ***
  • Posts: 1014
  • Country: hu
Re: EEVblog #405 - Lecroy 9384C Oscilloscope Repair - Part 3
« Reply #25 on: December 31, 2012, 10:42:30 am »
I wish Dave would at least cut the 3 other chips off to show the short going away.
and the short still exist and it was all along under the metal can :P
 

Offline cengland0

  • Contributor
  • Posts: 49
Re: EEVblog #405 - Lecroy 9384C Oscilloscope Repair - Part 3
« Reply #26 on: December 31, 2012, 03:30:03 pm »
Something being "worth" depends a lot on how much money one has.

...

Actually, I try to repair everything before giving up and buying a new device. If I can do it, I save some money (because the replacement parts do not cost as much as the new device).
I have a different opinion.  If it takes you 2 hours to fix a product that you could purchase for less than your hourly wage, it doesn't make much sense to fix it.  Just do some overtime or work a couple extra hours and buy a new one.

Edit:  Looks like tinhead already said the same thing.
« Last Edit: December 31, 2012, 03:32:28 pm by cengland0 »
 

Offline TheWelly888

  • Frequent Contributor
  • **
  • Posts: 344
  • Country: gb
Re: EEVblog #405 - Lecroy 9384C Oscilloscope Repair - Part 3
« Reply #27 on: December 31, 2012, 04:33:51 pm »
"One sick puppy" now put to sleep...

Still it was interesting to watch Dave investigate the fault and I learned one or two tips for faultfinding electronic gear so it wasn't a complete waste of time - Thanks Dave.  :-+

Some of the posts on this thread makes me regret the lack of a "Like This Post" button on this forum!
You can do anything with the right attitude and a hammer.
 

Offline SeanB

  • Super Contributor
  • ***
  • Posts: 16386
  • Country: za
Re: EEVblog #405 - Lecroy 9384C Oscilloscope Repair - Part 3
« Reply #28 on: December 31, 2012, 04:44:10 pm »
Yes, every time I try to rate a thread I get an error that I am not allowed to do so..........
 

Offline max-bit

  • Frequent Contributor
  • **
  • Posts: 685
  • Country: pl
Re: EEVblog #405 - Lecroy 9384C Oscilloscope Repair - Part 3
« Reply #29 on: December 31, 2012, 05:03:49 pm »
Now, it's (definitely) will not work :)
But I laughed, with the drill - grinder
  good job, Dave!
 

Offline Rick

  • Frequent Contributor
  • **
  • Posts: 315
  • Country: tr
Re: EEVblog #405 - Lecroy 9384C Oscilloscope Repair - Part 3
« Reply #30 on: December 31, 2012, 05:13:22 pm »
To make sure that it's the ASIC's that are faulty, aren't there specific signal levels that you can measure on their pins to pinpoint the fault, rather than to make assumptions. I am only asking the question.
« Last Edit: December 31, 2012, 05:59:43 pm by Rick »
 

Offline max-bit

  • Frequent Contributor
  • **
  • Posts: 685
  • Country: pl
Re: EEVblog #405 - Lecroy 9384C Oscilloscope Repair - Part 3
« Reply #31 on: December 31, 2012, 05:13:46 pm »
Which IC (diode or capacitor?) Is broken? not verifiable ....
The damage can be any item, and this multi-layer PCB
I do not know how to run a (paths) supply
In practice, the service, to replace the entire motherboard goes.
Dave good try ... but unfortunately the damage probably somewhere in a hybrid system .... and they probably be GaAsFet technology ....
 

Online AndyC_772

  • Super Contributor
  • ***
  • Posts: 4322
  • Country: gb
  • Professional design engineer
    • Cawte Engineering | Reliable Electronics
Re: EEVblog #405 - Lecroy 9384C Oscilloscope Repair - Part 3
« Reply #32 on: December 31, 2012, 06:32:12 pm »
Dave

Did you every try figuring out which are the 3.3V and GND pins on that ASIC, and probing the chip itself to see if you can measure the fault?

(How sickening would it be at this stage to measure the power pins and find evidence of a perfectly normal, working power supply structure in there?!)

Offline SeanB

  • Super Contributor
  • ***
  • Posts: 16386
  • Country: za
Re: EEVblog #405 - Lecroy 9384C Oscilloscope Repair - Part 3
« Reply #33 on: December 31, 2012, 06:46:58 pm »
Considering that probably 40 or more pins are supply and ground around that package it will be hard to check, they often are not all connected internally, or have a high resistance between them. Often you find digital, analogue and io supply and ground rails, and application of voltage between them with others not connected can cause the chip to latch up.
 

Offline EEVBFan

  • Newbie
  • Posts: 1
Re: EEVblog #405 - Lecroy 9384C Oscilloscope Repair - Part 3
« Reply #34 on: January 03, 2013, 09:53:36 pm »
I am still curious to beat up against this snag, and hope to get a Part4

To certain sure the Asic are not involved scratch off the other two due the power pins story at the reply above here,
yeah we must have seen a temperature rise by scratching off the first one which was not

Therefore i think it is a "short" between the copper planes 3V3 and GND
the copper (power) planes are very large and therefore all contribute to dissipate this huge power loss therefore the board still looks cool  8) under heat detection camera

I think in one of the via(s) like mounting hole or other one(s) a tiny is short exist between the copper planes 3V3 and GND, Maybe it is possible to pick up the flow current by some probe at an scope to see where current is flowing,
other wise 3V3 trace can be cut to see if the short disapears and if there are none 3V3 traces only a 3V3 copper plane cut the pcb into half with a hack saw to catch and trace location of this snag
if the short has gone we know the short has to be at the piece of a half pcb :)

regards
 

Offline Nermash

  • Frequent Contributor
  • **
  • Posts: 257
Re: EEVblog #405 - Lecroy 9384C Oscilloscope Repair - Part 3
« Reply #35 on: January 03, 2013, 10:28:24 pm »
Just a thought, Dave probably created more media coverage on Youtube for LeCroy than all their other videos.
If I were somebody really smart in LeCroy, I sure would send him 4 new Asics and a new psu :D
Followed by the new HD scope of course...
 

Offline tom66

  • Super Contributor
  • ***
  • Posts: 7393
  • Country: gb
  • Professional HW / FPGA / Embedded Engr. & Hobbyist
Re: EEVblog #405 - Lecroy 9384C Oscilloscope Repair - Part 3
« Reply #36 on: January 04, 2013, 10:28:03 pm »
I doubt they even have parts for these models any more.
 

Offline grumpydoc

  • Super Contributor
  • ***
  • Posts: 2951
  • Country: gb
Re: EEVblog #405 - Lecroy 9384C Oscilloscope Repair - Part 3
« Reply #37 on: January 04, 2013, 10:55:40 pm »
Quote
I doubt they even have parts for these models any more.
They do, in fact, have some spares available (though I very much doubt that includes a motherboard or ASICs) - I enquired about buying a new front panel for a 9354 I acquired which had some broken encoders and they did still have them.

Admittedly the reason that the still have them is probably that they wanted more than twice what I paid for the 'scope so I declined. But if I'd had deep enough pockets I could have bought one.
 

Offline bminish

  • Newbie
  • Posts: 1
Re: EEVblog #405 - Lecroy 9384C Oscilloscope Repair - Part 3
« Reply #38 on: January 05, 2013, 02:30:03 am »
It's a bit of bodge but I have in the past successfully unsolderd  chips like this by threading thin(ish) enamelled wire behind each row of pins in turn and pulling forwards as I reheat with a meaty soldering iron. As the wire slips out it lifts the pins.
You have a somewhat better chnace of having a chip you can reuse than if you use the Xacto Knife
Brendan   
 

Offline ejeffrey

  • Super Contributor
  • ***
  • Posts: 4062
  • Country: us
Re: EEVblog #405 - Lecroy 9384C Oscilloscope Repair - Part 3
« Reply #39 on: January 08, 2013, 01:09:54 am »
[quote author=EEVBFan link=topic=13083.msg177673#msg177673
Therefore i think it is a "short" between the copper planes 3V3 and GND
the copper (power) planes are very large and therefore all contribute to dissipate this huge power loss therefore the board still looks cool  8) under heat detection camera
[/quote]

No way.  You would easily see a plane-to-plane short under the thermal camera.  Once Dave looked with the IR camera and the only major hotspots were the ASIC heatsinks it was game over.  It was obvious that they were the culprit and all 4 were blown.  Other components may be damaged as well, but those asics are dead dead dead.
 

Offline electronics man

  • Frequent Contributor
  • **
  • Posts: 686
  • Country: gb
Re: EEVblog #405 - Lecroy 9384C Oscilloscope Repair - Part 3
« Reply #40 on: April 15, 2014, 02:38:57 pm »
I know this is an old thread, but i cant stop thinking it is something under that metel can, surely it would have been worth desoldering it to be sure?
follow me on twitter @get_your_byte
 


Share me

Digg  Facebook  SlashDot  Delicious  Technorati  Twitter  Google  Yahoo
Smf