Author Topic: Lecroy Wavesurfer Xs CPU Upgrade - BCM MX855 BIOS  (Read 222 times)

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Offline Momchilo

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Lecroy Wavesurfer Xs CPU Upgrade - BCM MX855 BIOS
« on: February 11, 2021, 10:52:39 pm »
Hi,
I'm in the process of upgrading an old Lecroy Wavesurfer Xs scope with a better CPU instead of the Celeron M320.
It's a BCM MX855LC mainboard with an Intel 855GME chipset with 400MHz FSB and the mPGA478C socket (manual of similar board.
So I replaced the Celeron with a Pentium M765 SL7V3. But the PC isn't booting anymore. The fans spin, but no image or beep. I guess the BIOS version is too old and doesn't support Dothan CPUs. It's v1.02.
The manufacturer has a list of legacy hardware and theoretically still offers the old software for it (http://www.bcmcom.com/bcm_support_driversAndBiosDownload.htm). But many links on the page no longer work and of course the one for the MX855. I couldn't find anything for the installed MX855LC. I guess it's the same BIOS firmware as for the MX855.
It works flawlessly with the Celeron. I ordered also two different CPUs (Intel Pentium M 1.6GHz SL6FA and Intel Pentium M 735 SL7EP) just in case I bought a broken one or the Dothan series isn't supported at all (not arrived yet). I also asked the manufacturer BCM for the latest BIOS version for the motherboard.

Does anyone have a newer BIOS version than v1.02 for the MX855LC mainboard or know how do you get the CPU running on this machine? It should be compatible.
Thanks for your effort :)

Best regards
Momchilo
 

Offline Algoma

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Re: Lecroy Wavesurfer Xs CPU Upgrade - BCM MX855 BIOS
« Reply #1 on: February 12, 2021, 02:03:02 am »
Here is a past thread, with a similar upgrade to the same Mainboard: https://www.eevblog.com/forum/testgear/teledyne-lecroy-wave-runner-(m)xi-upgrades-wrxi-wrmxi-series/

Appears to be more related to memory and FSB timing.  They upgraded to a Pentium M 780 @ 2.26Ghz .. even faster than that M765. I see a few on eBay.

The mainboard manual from BCM mentions a clear cmos is required to reset the memory timings (not certain if this is an advisable step for this particular application), and that matching speed memory modules are required with the higher Bus Speed of the Pentium chip, for the system to boot, as noted in the BCM MX855 manual.

I find a few similar active discussions on the subject in this group here: https://groups.io/g/LeCroyOwnersGroup
« Last Edit: February 12, 2021, 05:39:07 pm by Algoma »
 
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Offline Momchilo

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Re: Lecroy Wavesurfer Xs CPU Upgrade - BCM MX855 BIOS
« Reply #2 on: February 12, 2021, 11:00:34 pm »
Thank you Algoma for the tips and links. Since both CP4Us have the same FSB frequency of 400MHz, there shouldn't be a conflict. I made a CMOS reset and tried different RAM modules. At the moment it's a 1GB 400MHz Kingston module that is recognized by the mainboard with the Celeron without any problems.
But I tried every possible combination and it's still not booting  :-- But there aren't a lot of settings regarding timings and similar stuff. The BIOS is very simple.
I just hope that the delivered 765 is faulty which I tried to get running. For every change in the BIOS I have to swap the CPUs, it's not that much fun.

 

Offline darchons

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Re: Lecroy Wavesurfer Xs CPU Upgrade - BCM MX855 BIOS
« Reply #3 on: February 21, 2021, 02:42:40 am »
Hi Momchilo,

I am in the process of upgrading a 104MXi, and I have attached my BIOS, which appears slightly newer than yours (1.0.3A from October 2007).

Would you be willing to upgrade your BIOS to this version, and let me know if it works with the 765 CPU? I think you can use this flash tool, https://www.wimsbios.com/files/flashers/awardwinflash/awardwinflash194.zip

Thanks!
 
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