Author Topic: EEVblog #405 - Lecroy 9384C Oscilloscope Repair - Part 3  (Read 19826 times)

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Offline EEVblog

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EEVblog #405 - Lecroy 9384C Oscilloscope Repair - Part 3
« on: December 30, 2012, 07:52:44 am »


Dave.
 

Offline Pentium100

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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

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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

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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

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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

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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.
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Offline ftransform

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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

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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

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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

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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

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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

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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

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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

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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

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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

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« Last Edit: December 30, 2012, 07:11:23 pm by CarlG »
 

Offline jancumps

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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

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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

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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

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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
 

Offline IanJ

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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.
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Offline ZekeD

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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

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Re: EEVblog #405 - Lecroy 9384C Oscilloscope Repair - Part 3
« Reply #21 on: December 30, 2012, 11:57:02 pm »
+1 :-+

Offline krenzo

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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

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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

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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
 


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