EEVblog #217 - Lecroy 9384C Oscilloscope Teardown

[Imryan19]

my grandpa works for lecroy

[billynightmare]

Hi Dave, I have been looking into getting a Oscilloscope but the prices are way way above my budget atm, is there any Digital Oscilloscope I could use with my PC or even my arduino? could you recommend any software that will use my PC?

[datahelg]

Dave, there is a built-in diagnostics/development menu that will list all of the calibration data and will tell you which areas are out of spec and what their values are.

To access it (may or may not work for your scope, works on my 9310L scope and some others) press and hold the third soft-button (buttons next to the CRT) and while keeping it pressed, press the fourth then fifth buttons in rapid succession. This should bring up the development menu. It may take a few tries to get it.

[mikedelectric]

Dave, when will you finish troubleshooting this Unit?

[aljaz55]

I would start diagnostics and troubleshooting at the connectors. Most erratic behavior comes from bad connectors or old electrolytic caps.

As you found out some of the multi-pin connectors are not even soldered and copper has some dark oxide on it. This could be the first part I would try to fix. As well as disconnecting, cleaning and reconnecting all other connectors I can find. Problem seems to be somewhere in the digital side. I couldn't find the calibration NVRAM (backed up by battery).

[wongstein]

Great video. Very useful comments. I think the extra power supply output and a lot of that space might be for an optional on-board thermal printer which some have.

[XActSafeX]

Can you let your cat out of the closet ?

[ubuntututorials]

I would think the crystal is damaged. Sometimes they can crack and give erratic behaviour. The vibration from the fan might be causing the jittering and the jump in the middle of the waveform.

[joshstube]

Dave, another though on possible "repair videos", you could also let us take our cracks at it from the comment section!

How about it!?!

[joshstube]

Hey Dave!

Can this be a regular part of your Blog?

What if you were to buy some "parts only" items from eBay and attempt to fix them or at least finger the problem with them ???

I would think that your engineering background would suit you well for this sort of task, what do you say?

[rasz]

Loved the video, cant wait for troubleshooting part.

I would suspect logic behind ADC and before Motorola CPU. Maybe one of the SRAM chips is fried. It looks like the scope uses all of them even in one channel mode.

Maybe you can find more test/diagnostic modes under rs232 terminal?

[NoIsrahell]

Yokowaga is number one in my book.

[pidgeoninthecoop]

So Dave, just as a guess, how many man-hours would it take to design this scope, from the ground up, excluding custom chips and software? Give or take a factor of two.

[EEVblog]

@pidgeoninthecoop That answer has too many variables... Depends entirely on how much ground work you had already done and experience gained on previous designs, partitioning of design teams, project management etc. It could be as little as a year, or as long as several years.

[brianhoskins1979]

Forget the fan noise, I could have sworn I heard it crying like a baby part way through the video!!!

[ashsama2]

That's just simply beautiful design of the motherboard....

[gmaildotcom]

What caused the mains trip at the begining?

[EEVblog]

@gmaildotcom Obviously leakage from all the dust in the power supply. After it was cleaned out it now longer trips.

[jorgeandrade20]

Please do post a video on the troubleshooting and fixing part, I just bought a Tek 2465A that needs some work and your video will help immensely!!

[TheXGamer969]

Yay, fixed the aspect ratio of the video! Good job Dave!

[excavatoree]

I think this is the first CRT shown on the EEVBLOG.

[excavatoree]

@excavatoree I forgot about the Tek scope. So, that makes this the second CRT. (but first raster-scan)

[kiyotewolf]

Do another video on Project Sagen! Sagan?

[EEVblog]

@kiyotewolf Sagan, as in Carl Sagan.

[tubefella]

You're a bit harsh on the use of TO220 standup devices Dave. No problems after 12 years and they'll still be fine after another 20! With three leadouts the weight to lead compliance ratio is very low unlike say an untethered 10W power resistor which you often see and is definitely unacceptable!

[EEVblog]

@tubefella Put it on a trolley out in a production environment where it is wheeled around all the time, and then report back in a few months :->

[MrDubje]

Cool scope, a very compact (crowded) power supply...

to bad about the damage... I hope you can fix it.

Those old memory sticks (EDO RAM?) don't have gold plated contacts, do they? I don't know if it is in relation with the problem (or part of it), but I would clean them anyway.

[0LoneTech]

Those Darlington arrays are probably for actuating the relays.

[jpelczar]

I wonder if this floppy disk turd uses the same interface as PC (to create floppy simulator using SD card)

[Zadster]

Given the damage to the case, the first thing I would suspect would be a bad connection. Either on the ribbon cables or the socketed ICs/modules. *taptaptap* around with an insulated screwdriver handle and see what happens. I suspect I am teaching my grandma how to blow eggs there. The Bt (Brooktree) chip is a video DAC.

[DanFrederiksen]

cats are adorable little selfish bastards : )

[chris1seto]

Is that a quadcopter in the background? Aeroquad if I'm not mistaken? ;)

[TheEPROM9]

Did cleaning it get it fully operational, or is there something more sinister lurking in the electronics.

[EEVblog]

@TheEPROM9 The cleaning didn't work I'm afraid, more troubleshoting will be required.

[CampKohler]

Do you suppose there is another 9384C somewhere in Sydney? If you could get together with another owner and you could swap modules until you find the problem. I wonder if there is a group (ham radio, etc.) in Aus that could find you another owner.

[CampKohler]

Looks like a second scope will come in handy for fixing this one.

Note that the Ch1 & Ch2 ADC heat sinks aren't just shorter (to clear the PS), but also have a different footprint and metal thickness. That's odd.

The loopy coax looks like it's longer to achieve a timing objective.

If the RAM stick is std., you could change that out just because you can.

Do you have JB-Weld in Aus? That would be good for case repair. You could drill fine holes into the thickness of the case and force in glue.

[fettfettmerafett]

When will someone make an oscilloscope for left handed people?

[thewii552]

@fettfettmerafett now there is an idea...

[CampKohler]

@fettfettmerafett Since left-hander's brains obviously work backwards from the rest of us, there shouldn't be too much problem adapting to things being upsidedown. Just turn the scope over!

[fettfettmerafett]

@CampKohler

That's how we roll!



[turbochargedbrick]

the ULN driver is obviously for software control of the relays on the front end.

[pret83]

Hi Dave. Do you plan som sort of tutorial, like your DC-DC converter tutorial? Teardown old devices is ok, but I think, the audience appreciate more some valuable content. Can you do some list of jelly-bean components (like voltage regulators, opamps etc.) and short description of them... ? I would appreciate it a lot. I'm a big van of you anyway. 

[zaprodk]

Dave, How much did you pay for it ? Regarding the screen burn-in - i'd rotate the CRT 180 degrees, that would lessen the annoyance a bit!

[BeJ95]

@zaprodk Good idea, but I don't think the HT lead would be long enough though...

[zaprodk]

@BeJ95 I'd done that before, use some HT cable from another CRT monitor, solder it up and insulate with two layers of heatshrink with glue. Works a treat!

[zaprodk]

Dave, How much did you pay for it ?

[jakent11]

One of the messages that shows up for a brief moment.. "Delay cal signal railed! ch 2"

[tagno25]

many of the .1 inch headers look like test points

[epatto]

I saw a few 0.1" headers labeled TP, so those are probably the test points.

[Photonface]

The coaxs are maybe delay lines?

[KiloSierraAlpha]

Awesome!!! PLEASE do the troubleshooting vid and show how you fix it. Thanks!

[jerzmacow]

I'm not a fan of the fly overs...it's weird to not hear you talking for more than 10 seconds

[CampKohler]

@jerzmacow I like the flyovers. I can actually feel my brain analyzing everything like some kind of scanner shooting out laser beams. You can always skip over them. (Maybe Dave will sell a "flyover passifier;" when you suck on it, it outputs, "I LOVE it!" in his voice. :-) )

[teemune]

@jerzmacow Yeah. I thought I had my audio muted and had to rewind to check. >:(

[fingerboy18]

Are those board interconnects by Amphenol? I used to work there and those connectors looks quite familiar. I know there are dozens of manufacterers. They used similar connectors for jet's backplanes.

[heroineworshipper]

Need to get some bodge.

[broccabronson]

There is another bodgy resistor in IC A15 at 26:33 :)

[GTXAbunada]

We want more tutorials dave! Transistor tutorial or something

[mckaymatts]

Is that a cat in the background? For your next review, cover your cat! (No teardown, please)

[EEVblog]

@mckaymatts No, I don't have a cat, I hate cats!

[LegionForTheLulz]

@EEVblog Oh, careful! Don't say anything bad about cats on the internets. ;)

[CampKohler]

@mckaymatts I wonder if that cat is named Sagan?

[hoppes9]

At least it isn't running Windows NT like some Tektronix scopes of that era did!

[samgab]

@EEVblog Ouch! You're probably going to lose that thumbnail!

[EEVblog]

@samgab Possibly! That's what you get when you close a door and your thumb is still in the door jam...

[randomgarfield]

HA that BT481 is a true colour RAMDAC I recognise. I wonder if they made a colour version.

[PhattyMo]

Those connectors on the SRAM boards and stuff aren't soldered? I'd probably start there,it's bound to be a minefield of bad connections!

[Vlakpage]

@PhattyMo Yeah, I don't get how can all these pins get good connection without soldering.

[CampKohler]

@Vlakpage There are two ways the pins can make contact as good as soldering. One way is the have split springy pins that are forced into the vias. Another is to just push solid pins into slightly small holes such that there are four gas-tight joints made at the corners. Either has the advantage of easy assembly without the chance of solder bridges and it gives the possibility of connector replacement without having to get all those pins perfectly desoldered.

[MercenaryNL]

Nice video; I was wondering if you were going to try to troubleshoot the problems. Will be waiting for that video.

[ivaneduardo747]

Oh wait, it's the same video! >: |

[ivaneduardo747]

I was a bit disappointed in the previous video because you didn't find the problem, but I am happy now. :)

[thewii552]

ooh, nice. How did you manage to get this scope?

[Cabose1fn]

my dad has been talking about how if he had an oscilloscope for every. what is a good brand/model to look for?

[dubbbear]

But can you play tetris on it ?

[the79jinx]

I would have loved to have my hands on one of those in 1996 or some!