EEVblog #405 - Lecroy 9384C Oscilloscope Repair - Part 3

[EEVblog]

Dave.

[Pentium100]

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.

[peter.mitchell]

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

[justanothercanuck]

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... 

[JoannaK]

Ah well.. Sometimes it just happen. 

[firewalker]

Just juice it up with 40 amps! 

Alexander.

[ftransform]

send it to photonic induction

[Ketturi]

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

[SeanB]

Better to lift it with the Quadcopter and release it from a height, at least it will make for a nice bang...........

[obsoletemac]

Hi (My first post  )
Would it be possible to get that little heatsink off to see what that ASIC-ish IC is?

//c

[RoelA]

@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

[SeanB]

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.

[ftransform]

does anyone else think it might be the second asic? It did get 2 degrees hotter after all.

[SeanB]

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.

[CarlG]

@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

[jancumps]

Auction it for charity.

[Winston]

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.

[tinhead]

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

[G7PSK]

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

[IanJ]

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.

[ZekeD]

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.

[robrenz]

+1

[krenzo]

I wish Dave would at least cut the 3 other chips off to show the short going away.

[McMonster]

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.

[gazza666]

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