Author Topic: LeCroy Waverunner 6200 Repair  (Read 7484 times)

0 Members and 1 Guest are viewing this topic.

Offline chubbymonkTopic starter

  • Contributor
  • Posts: 26
  • Country: au
LeCroy Waverunner 6200 Repair
« on: December 19, 2023, 04:21:54 am »
I recently acquired a Lecroy Waverunner 6200 in non-working condition and have been working on it on and off for a couple months with no luck. I've included screenshots of relevant areas of the service manual and schematics in the post but full service manual and schematics can be found on KO4BB. Any help would be greatly appreciated!

Initial Symptoms:
When I first got it, it still had Windows 2000 which started but refused to boot. My initial thoughts was that it was probably just a corrupt windows installation so I saved an image of the original hard drive (including all the calibration data) and upgraded it to Windows XP with an SSD. When it came to installing all the scope software it would crash near the end of the software installation (entire PC would freeze and become unresponsive, requiring a hard power restart). After some software trouble-shooting I found that it crashed specifically when it went to install drivers for the LeCroy S65 PCI device, which is the PCI card that links the PC portion of the scope to the acquisition portion. I could reliably replicate the crash by trying to install the drivers manually using either LeCroy's provided driver installation in the software directories or Windows automatic driver detection and installation that now appears on startup.

The X-Stream software starts but raises the error of "No hardware detected, not authorised to run on this system" (exact wording might be different, writing this from the top of my head). I suspect that this is primarily just caused by the lack of the PCI card driver meaning that the software has no way to communicate to the acquisition board.

Troubleshooting:
Initial troubleshooting of checking all the voltages (were done at either output of regulators or main power supply connectors) and various clocks were done (except the 10Ghz clock as I have no equipment to test that).

The debugging guide in the service manual point towards replacing the PCI card and the entire acquisition system but I think we can do a bit better than that. The theory operation in the service manual points out that on startup there should be two beeps which indicate a good "connection" between the PCI card and the acquisition system (denoted by MB, not the computer MB), I don't get any beeps with my scope so indeed there is a problem with the LVDS connection between the PCI card and the MB. I confirmed that there is indeed a problem with the LVDS communication by probing the LVDS lines and there is indeed no communication between PCI and the MB, on startup all the data lines and the reset error line (almost) immediately go high, with only the sync and clock lines actually having any signal. More on probing and JTAG later.

The entire architecture of the PCI card and the MB is composed of 3 Xilinx XC2S200E's, a PQ208 quad flat pack on the PCI card and 2 BGA FG456's on the MB. From the service manual, the one on the PCI card acts as a transaction repeater for the PCI interface. On the MB there is one FPGA which acts as the main control FPGA and the other FPGA doing something to do with the timebase. The FPGA on the PCI card communicates with the control FPGA via LVDS which is connected using 2 forty pin special ribbon cables. (Note: these can be easily probed at from the PCI card connector which is TH). See various block diagrams below:
System block diagram:

MB block Diagram:


Given these were FPGA's I chased a red herring checking if they were configured correctly with proper bitstreams. From the schematic and probing they all operate in Slave Serial mode and are configured externally by an Infineon C161PI microcontroller on the MB. The FGPA on the PCI card is configured first using a separate CCLK line with a shared DIN line, then the two on the MB are configures in a serial chain. From what I can tell by directly probing the DIN and various CCLK lines as well as looking at the DONE signals by the FPGA's, they are all configured correctly. This is also indicated by a red LED on the MB which goes off after the FPGA's have been configured (released DONE from a low state).

I managed to get JTAG access to all the PCI card FPGA and the control FPGA, the other devices on the MB had some weird JTAG configuration with certain populated and unpopulated zero ohm jumper resistors which I couldn't figure out. From the JTAG access I performed boundary scans on both FPGA's and indeed there is no LVDS communication at all as confirmed by directly probing the LVDS lines from the PCI Card connector. From probing directly I can see that the FPGA's initialise the LVDS data pins in that they drop down from the main supply voltage to a low LVDS level for 400ns before going to a high LVDS level with no further activity or data at all. This is the part which confuses me a bit, I would have expected that they try to do some sort of handshake or something like that but from what I can see, they don't "attempt" to transfer any data at all, just immediately going high. The LVDS clock and sync signals are always present though. See the schematics below.

PCI card Troubleshooting:
From the boundary scan of the PCI FPGA, I can see all the relevant PCI activity when windows communicates during startup and driver installation (when it crashes). So in the below schematic, the left hand side with the PCI interface looks to be working, but there is no activity on the right hand side with the LVDS interface.
As a note I thought RX_TXSTABLE, RX_RXSTABLE, TX_TXSTABLE, TX_RXSTABLE (pins 38,40) on J1, J2 of the LVDS interface, might have something to do with a handshake of some sort but I couldn't figure anything out. They all have pullup resistors to 3V3 (some on PCI card and some on MB) and RX_RXSTABLE and TX_RXSTABLE are high while the other two are low. But I couldn't figure anything further than that out.
PCI Card Schematic:


Control FPGA Troubleshooting:
Also, from the boundary scan of the control FPGA, I can see the relevant activity on the MAM_IN and MAM_OUT buses (8B/10B Gigabit Ethernet) which goes to and from the actual acquisition devices (ADC and acquisition memory readout) as well as the UC_D and UC_A (Parallel interface) which is communication to and from the C161PI microcontroller. However, there is also a number of devices for which there is seemingly no activity to and from the control FPGA. There is no activity for all of the following items.
- As mentioned previously, there is no activity on the LVDS lines, LVDS_IN and LVDS_OUT. Apart from the LVDS clock and sync lines.
- There is also no activity in the SDRAM interface. According to the theory of operation the SDRAM is used for timestamp in sequence mode. Which given that the scope hasn't triggered might be correct that there is no activity??
- JTAG interface to timebase FPGA and acquisition system, according to theory of operation, the control FPGA uses JTAG as a "serial interface to communicate" with the devices. Might not be an issue as we aren't receiving any commands to relay on to the timebase or acquisition system??
- SPI interface for control of DAC's and Front End. Again might not be an issue that there is no activity as we aren't changing any of the FE settings??
- some interface to the timebase FPGA, no clue what type of interface this is but also not present. Could this be the issue??
See schematic below for control FPGA section:
Control FPGA Schematic:




Anybody have any pointers on what might be wrong or where to look next? Or if anybody with a working scope can probe the start of the LVDS lines or the RX/TX_STABLE lines that would be great. Any commentary or help at all would be greatly appreciated!
 

Offline Teichhermelin

  • Regular Contributor
  • *
  • Posts: 96
  • Country: de
Re: LeCroy Waverunner 6200 Repair
« Reply #1 on: December 19, 2023, 08:04:32 am »
Hello, if I can help you with an image of a working XP device, I would create it for you.
 

Offline chubbymonkTopic starter

  • Contributor
  • Posts: 26
  • Country: au
Re: LeCroy Waverunner 6200 Repair
« Reply #2 on: December 19, 2023, 08:30:09 am »
Thank you for the offer! But I don’t think it’s a software issue unfortunately. I think I’ve already got the correct drivers and software from the LeCroy website.
 

Offline shakalnokturn

  • Super Contributor
  • ***
  • Posts: 2124
  • Country: fr
Re: LeCroy Waverunner 6200 Repair
« Reply #3 on: December 21, 2023, 12:02:03 am »
On PCI card 1.8V supply is spot-on ?
What does the FPGA fetch from U11 - DS2433 ?
I once had a DSO dead to windows because the PCI board couldn't load configuration from a defective I²C EEPROM. It wasn't a LeCroy.
 

Offline chubbymonkTopic starter

  • Contributor
  • Posts: 26
  • Country: au
Re: LeCroy Waverunner 6200 Repair
« Reply #4 on: December 21, 2023, 01:35:52 am »
PCI Card 1.8V rail is spot on.
Forgot to mention in the initial post but one of my initial suspects was the EEPROM as well. I ended up pulling it from the board and was able to read the Scope ID and options so I assume it's fine as well. Additionally, I read from the LeCroy "options" thread on the forum that others who had messed with the EEPROM to enable certain options just cause the scope to enter some sort of demo mode and not the no hardware authorised error.

Also, I hooked up a UART adapter to the RS232 port of the C161PI microcontroller (according to service manual it's used to program flash storage) and got the following output:

Seems like the microcontroller can't get the various ID's of the FPGA's? But could this just be related to the lack of communication with certain things on the control FPGA?
 

Offline smaultre

  • Regular Contributor
  • *
  • Posts: 141
  • Country: us
Re: LeCroy Waverunner 6200 Repair
« Reply #5 on: December 27, 2023, 08:58:15 am »
Hello i have some experience with repairing restoring and modding of these series.
And xi, mxi versions they have same architecture.
I can try to help with yours troubles.
First you need to check all power rails of acquisition board. It's need to be powered ~50-100ms after PC board
Then you need to check quartz generators on PCI and ACQ board. I have one scope now, and can remove ribbon cables try to simulate yours situation, and make any measurements up to 10 GHz.
Start a new life here!!!
 

Offline chubbymonkTopic starter

  • Contributor
  • Posts: 26
  • Country: au
Re: LeCroy Waverunner 6200 Repair
« Reply #6 on: January 03, 2024, 07:20:11 am »
Hi smaultre,
The power rails all seem to be fine, both in terms of voltage level and ripple.
I've confirmed the two quartz oscillators I could find on the PCI and ACQ boards (125MHz and 60MHz for the FPGA and microcontroller respectively). I was also able to somewhat measure the 500MHz clock (couldn't measure at final destination but instead at some ECL converter, it's a bit confusing to measure with the changes from TTL to ECL and vice versa) for the timebase ASIC.

If you could measure any activity on the RX/TX_STABLE lines (or any activity on the LVDS which resembles a handshake) from the PCI card that would be really helpful.

I'm starting to suspect that it might just be some unusual failure of the main glue FPGA that causes either only a few banks to be faulty or some internal logic gone bad.
 

Offline ollopa

  • Regular Contributor
  • *
  • Posts: 121
  • Country: 00
Re: LeCroy Waverunner 6200 Repair
« Reply #7 on: January 18, 2024, 01:29:19 pm »
You are correct that the "No hardware detected" popup is caused by the lack of the S65 driver.  I'm not sure if the driver crashing is a hardware or a software problem, though, I have never had the scope crash when loading the driver before.  I believe the driver should load and not crash even with the ribbon cables to the acq board disconnected, so you may wish to try that and / or try different PCI slots or putting the card into another motherboard and trying to attach the driver under XP.  Just try to narrow down the scope of the troubleshooting and find the pattern -- does the problem follow the card or the motherboard, does it involve the acq board at all, etc.
 

Offline Kosmic

  • Super Contributor
  • ***
  • Posts: 2540
  • Country: ca
Re: LeCroy Waverunner 6200 Repair
« Reply #8 on: January 18, 2024, 02:25:17 pm »
Did you check all the capacitors on the PC motherboard ?

I had a Tek scope where the capture card driver was crashing in windows and the problem was simply some bad capacitors on the motherboard interfering with PCI communication.

I'm also currently working on a Waverunner 6100 and need to recap the whole motherboard (same for the powersupply  :phew:). In this case, some caps actually vented and the problem was clear. For the Tek scope it wasn't that clear since the caps visually looked OK.
« Last Edit: January 18, 2024, 07:37:03 pm by Kosmic »
 

Offline chubbymonkTopic starter

  • Contributor
  • Posts: 26
  • Country: au
Re: LeCroy Waverunner 6200 Repair
« Reply #9 on: January 19, 2024, 06:01:47 am »
@ollopa
If I recall correctly, at the very beginning I think I did try installing the driver with everything disconnected and I believe it still crashed. My reasoning to believing that it was a hardware error is the lack of the double beep at startup which indicated the link between the PCI card and the acquisition board was bad which is irrespective of software (based purely on the interaction between the FPGA's)? I'll give disconnecting everything then installing the driver another go though, to double check.

Edit: Tried disconnecting the PCI card and the acquisition board before installing the drivers, the driver install no longer crashes but now gives the error that no LeCroy hardware is connected and exits itself. This cements the idea in my mind that it's probably some sort of hardware error that borks the communication between the PCI card and the acquisition board (also would explain the lack of the two beeps as well as what was measured on the LVDS lines).

@Kosmic
Interesting, my PC motherboard did indeed have leaking caps! I removed the severe ones and didn't get to replacing any of them yet as the motherboard seemed to work fine for testing. I'll give it a closer look, and might just recap the whole motherboard then.
« Last Edit: January 19, 2024, 06:23:47 am by chubbymonk »
 

Offline smaultre

  • Regular Contributor
  • *
  • Posts: 141
  • Country: us
Re: LeCroy Waverunner 6200 Repair
« Reply #10 on: January 20, 2024, 11:48:36 pm »
Try first to recap motherboard and check Windows stability.
Start a new life here!!!
 

Offline Alex_twn

  • Contributor
  • Posts: 10
  • Country: tw
Re: LeCroy Waverunner 6200 Repair
« Reply #11 on: January 22, 2024, 03:58:19 pm »
I just bought a broken WR6050 that was instable and not able to start the DSO application.
A quick visual inspection showed that the 3300uF/6.3V cap on the Intel motherboard were all dry and opening up at the top.
I changed the capacitors and the scope is working now perfectly.
Easy fix.
 

Offline chubbymonkTopic starter

  • Contributor
  • Posts: 26
  • Country: au
Re: LeCroy Waverunner 6200 Repair
« Reply #12 on: January 25, 2024, 08:44:51 am »
Unfortunately, no luck with replacing the leaking caps (which I had previously removed), they were the same 3300uF/6.3V ones as Alex's but I'm still getting the same error, with windows completely freezing when trying to install the drivers.

@Alex_twn did you also get the "No hardware authorised" message or was the X-Stream software just stuck on like a loading screen or something?
 

Offline Alex_twn

  • Contributor
  • Posts: 10
  • Country: tw
Re: LeCroy Waverunner 6200 Repair
« Reply #13 on: January 25, 2024, 02:43:23 pm »
No I never had this "No hardware authorized" message, just the X-Stream software was hanging upon loading.
Did you try another motherboard to see if it makes any difference?
 

Offline chubbymonkTopic starter

  • Contributor
  • Posts: 26
  • Country: au
Re: LeCroy Waverunner 6200 Repair
« Reply #14 on: January 25, 2024, 09:53:18 pm »
I don’t have any suitable replacement motherboards on hand but, I did find a suitable replacement for sale locally for a decent price, will try the replacement when I get it later.

On a different note, Alex do you remember if before you replaced the capacitors, if you had gotten a double beep on startup?
 

Offline smaultre

  • Regular Contributor
  • *
  • Posts: 141
  • Country: us
Re: LeCroy Waverunner 6200 Repair
« Reply #15 on: January 25, 2024, 10:21:48 pm »
You need to replace ALL power caps, not only leaked.
Or you need to measure the ESR.
ESR maybe bad, but cap looks and holds capacity like new.
But it not works on high frequency dc-dc converter.
Start a new life here!!!
 

Offline chubbymonkTopic starter

  • Contributor
  • Posts: 26
  • Country: au
Re: LeCroy Waverunner 6200 Repair
« Reply #16 on: January 26, 2024, 12:57:37 am »
Yeah you’re right, I was just being lazy. Upon closer inspection, the 1.5V rail on the motherboard (which I presume is Vcore) has 400mV of ripple @ about 300KHz! I suspect this probably originates from the 12V rail which has 900mV ripple also at 300KHz which comes from the power supply.
Looks like it’s time to give the power supply a closer inspection, initially I had just checked the DC voltages and they were all spot on so I ignored to make the ripple measurements :palm:.

Edit: Here are (some of) the ripple measurements (tested both under load with the scope and also with a DC electronic load) measured at the connectors onto the acq board,

There's definitely something wrong with the power supply.


Opening it up there is a prior repair/service, with a peculiar service date which I can't seem to decipher.

With a number of components in the +5VSB (5V standby circuit) having been replaced. (A couple resistors and a mosfet, a couple control boards were also seemingly desoldered)...


I can't seem to find the cause of the noise yet, it's interesting how it's present on all the power rails though...
« Last Edit: January 26, 2024, 07:59:29 am by chubbymonk »
 

Offline Alex_twn

  • Contributor
  • Posts: 10
  • Country: tw
Re: LeCroy Waverunner 6200 Repair
« Reply #17 on: January 26, 2024, 11:56:52 am »
I don’t have any suitable replacement motherboards on hand but, I did find a suitable replacement for sale locally for a decent price, will try the replacement when I get it later.

On a different note, Alex do you remember if before you replaced the capacitors, if you had gotten a double beep on startup?

No there was no double beep at startup.
 

Offline Alex_twn

  • Contributor
  • Posts: 10
  • Country: tw
Re: LeCroy Waverunner 6200 Repair
« Reply #18 on: January 26, 2024, 11:58:35 am »
You need to replace ALL power caps, not only leaked.
Or you need to measure the ESR.
ESR maybe bad, but cap looks and holds capacity like new.
But it not works on high frequency dc-dc converter.

Indeed better. I have an ESR tester to check the caps.
 

Offline Alex_twn

  • Contributor
  • Posts: 10
  • Country: tw
Re: LeCroy Waverunner 6200 Repair
« Reply #19 on: January 26, 2024, 12:13:06 pm »
Yeah you’re right, I was just being lazy. Upon closer inspection, the 1.5V rail on the motherboard (which I presume is Vcore) has 400mV of ripple @ about 300KHz! I suspect this probably originates from the 12V rail which has 900mV ripple also at 300KHz which comes from the power supply.
Looks like it’s time to give the power supply a closer inspection, initially I had just checked the DC voltages and they were all spot on so I ignored to make the ripple measurements :palm:.

Edit: Here are (some of) the ripple measurements (tested both under load with the scope and also with a DC electronic load) measured at the connectors onto the acq board,

There's definitely something wrong with the power supply.


Opening it up there is a prior repair/service, with a peculiar service date which I can't seem to decipher.

With a number of components in the +5VSB (5V standby circuit) having been replaced. (A couple resistors and a mosfet, a couple control boards were also seemingly desoldered)...


I can't seem to find the cause of the noise yet, it's interesting how it's present on all the power rails though...

Ah yes this does not looks good…
I would say that the 1.5V will be more likely generated from the 3.3V rail for a lower dropout and this is as well the rail with the most current to supply the CPU.

If the ripple is everywhere I wouldn’t suspect the individual rails but the main switching stage at the primary after the bridge rectifier.
You can check C90 (100uF/25V) and C101 (22uF/50).
I have the schematics of the PSU if you don’t have them already.
« Last Edit: January 26, 2024, 02:26:44 pm by Alex_twn »
 

Offline chubbymonkTopic starter

  • Contributor
  • Posts: 26
  • Country: au
Re: LeCroy Waverunner 6200 Repair
« Reply #20 on: January 28, 2024, 04:27:33 am »
Thanks Alex! I've already got the schematics. I had to mock up a crude ESR tester to test the caps and I've replaced a number of caps in the 5V standby section which tested either completely bad or somewhat bad with my ESR tester (including C90 and C101 which you mentioned!). This definitely made an improvement, with the ripple basically halving from 1V p-p to 500mV p-p (under some load). I didn't get time to test in the actual scope yet but I'll probably take another look inside before doing a test reinstalling it in the scope. In total I had replaced, (C82, C100, C106, C90, C101).
 

Offline Alex_twn

  • Contributor
  • Posts: 10
  • Country: tw
Re: LeCroy Waverunner 6200 Repair
« Reply #21 on: January 29, 2024, 05:25:02 pm »
I just checked today the ripple on another WR6050 that I am deeply cleaning to make it as new and I was very surprised to see a large ripple on the motherboard power connector 3.3V while nothing on the acquisition board.
All the other rails are perfects.

Very strange as those are the same 3.3V rails. I checked the caps, like new, (this psu is so clean that it looks brand new or this WR6050 has very few running hours) anyhow I believe that there is a design flaws.

The 3.3V to the motherboard connector is a long wire that unlike the one for the acquisition board goes through inside all the PSU before going out at the other end and like a big antenna capture all the ripple of the big coils nearby.
Such a bad design.
Then this ripple I believe largely put under stress the 6.3V capacitors of the motherboard and they die prematurely.
I am quite sure this is the issue.
I already moved a bit this 3.3V cable far from the coils but the psu is compact so I don’t expect much difference.

I have the simple idea to make this cable going out of the psu from the same location as the 3.3V of the acquisition board and route it out outside of the psu simply.

Like this it should avoid picking some noise.
Probably a helpful tweak.
 

Offline shakalnokturn

  • Super Contributor
  • ***
  • Posts: 2124
  • Country: fr
Re: LeCroy Waverunner 6200 Repair
« Reply #22 on: January 30, 2024, 02:55:09 am »
@chubbymonk:
Some of the solders in your first PSU photo don't look great.
The 3 top right in the hot-spot near the 1k SMD resistor look awful
 What component(s) are they supporting?
 

Offline chubbymonkTopic starter

  • Contributor
  • Posts: 26
  • Country: au
Re: LeCroy Waverunner 6200 Repair
« Reply #23 on: January 30, 2024, 08:56:22 am »
I just checked today the ripple on another WR6050 that I am deeply cleaning to make it as new and I was very surprised to see a large ripple on the motherboard power connector 3.3V while nothing on the acquisition board.
All the other rails are perfects.

I have the simple idea to make this cable going out of the psu from the same location as the 3.3V of the acquisition board and route it out outside of the psu simply.

Interesting, I'll see how it's like on my PSU after I hunt down the source of the remaining 500mV p-p of switching noise on the outputs of mine. Don't have much spare time until the weekend to poke around again unfortunately.

@chubbymonk:
Some of the solders in your first PSU photo don't look great.
The 3 top right in the hot-spot near the 1k SMD resistor look awful
 What component(s) are they supporting?

I remember seeing this earlier as well, they support two large back to back power resistors, I just presumed that they get a bit hot in the nature of the design (or when the previous fault had happened). I had checked their values which were spot on and for the soldering, while it looked a bit dodgy it was definitely solid but yeah I should probably reflow them the next chance I get to poke around.
 

Offline chubbymonkTopic starter

  • Contributor
  • Posts: 26
  • Country: au
Re: LeCroy Waverunner 6200 Repair
« Reply #24 on: February 04, 2024, 11:14:05 am »
Still haven't had any luck finding the source of the switching noise...
After replacing C84 an SMD electrolytic on the VBIAS rail which didn't look bad but after desoldering had started to leak from the bottom. After replacing it, the low frequency ripple is gone but the 300kHz-ish switching noise is still present.
Probing around on the secondary (ground-referenced side), VBIAS, VBIAS2, S/D rails all have a significant amount of ripple, some reaching 1V p-p.
I'm still inclined to think that it must be something wrong on the primary side, as VBIAS, VBIAS2 and S/D are separate on the secondary side, on completely different transformers as well. (Not too sure what S/D actually does though...) (These are all used by the control cards in some way or another in feedback or elsewhere.
Probing around the primary side is a bit difficult with it not being earth referenced, quite puzzled at this stage...
 


Share me

Digg  Facebook  SlashDot  Delicious  Technorati  Twitter  Google  Yahoo
Smf