LeCroy WaveSurfer 24MXs-B Motherboard

[nctnico]

Did you try a different processor and RAM? Get a different board (known good) with processor and RAM so you can swap things over. I would have done that before attacking (and possibly damaging) the board!

[tppc]

Well, I actually have a second unit (fully working identical oscilloscope).
But :
- To gain access to the motherboard, you need to disassemble the whole instrument (tens of screws) + remove all other boards, which is a real pain in the butt
- I did not dare swapping parts from the good unit to the bad one, because, if I burn the good parts on the bad scope, then I would lose both units  . 

[nctnico]

I agree that using the parts from a working unit isn't the best idea.

For such tests you have to buy a motherboard that is compatible with the processor and the memory (preferably with processor + memory so you have a working combination but also make sure to buy a processor and memory). It doesn't matter whether this motherboard fits the oscilloscope or not, the intention is to find out which part is faulty. From what you have posted so far it seems you don't know whether the motherboard, processor or memory is faulty. The first step towards a succesfull repair is to determine which part is actually faulty.

[tppc]

I can be wrong, but my feeling is that :

a) RAM + CPU are OK
b) Motherboard is defective.

I removed both RAM + CPU and I still measure 8 Ohms across some unknown supply rail on the mobo.
(not on any of the ATX connector pins)
BTW all voltages on the ATX connector are OK.

My feeling is that there is some low voltage (1, something volts) generated on the motherboard that could be defective.
The problem is that there is no indication on the silkscreen that would show the low voltage rails, I don't know, 1.7 V or whatever...   

[nctnico]

Measuring 8 Ohm on a supply rail can be OK; it is not out of the ordinary. Again: first determine 100% which component (motherboard, CPU or memory) is actually faulty through elimination. Guessing leads to destroying good components.

[tppc]

Measuring 8 Ohm on a supply rail can be OK; it is not out of the ordinary. Again: first determine 100% which component (motherboard, CPU or memory) is actually faulty through elimination. Guessing leads to destroying good components.

OK, thank you for this information  , I thought it was too low. 

I will follow your indications and find a way to test CPU + memory.

Thanks. 

[nctnico]

With a working motherboard, you can also check supply voltages around the CPU and compare with your non-working board. Don't stick the 'new' CPU into the non-working motherboard immediately; use it to collect data on the working motherboard first.

[zhongzuocheng520]

Hello friend

I have a 44MXI-B fault that has not been resolved, but I have found a circuit diagram of the motherboard that is not customized. I hope it can be repaired. I hope this can help you

[coromonadalix]

the mainboard is supposed to be an       BCM MX945GME-LC  Notice the LC ending, it's because of the pc104 interface,  Custom board made for LeCroy .... seen that on some threads

The best bet  would be to find a BCM MX945GME   no lecroy variant and use an pci to pc104  converter

like this ?? 
https://www.winsystems.com/product/pci-ppm/
https://connecttech.com/product/pci-to-pc104-plus-adapter/

Ans if the coin cell batterie dies on some scope, the modo settings are lost and when the board boot  youll get many errors, if you mobo still boot

And i think you are going too fast to check  this and that,  the psu is always the prime suspect,  check if you can find the psu pinouts, and normally  you are supposed to  get an always present voltage,   IE:  a 5v standby  or some rare instance an 12v

The best would be to get an Intel 945 motherboard and try on it your cpu and ram


This is a BCM  EOL warning in 2011
https://www.bcmcom.com/e-ad/eletter_07282011_MX945GME_Last_Time_Buy_notice.htm                                 but i think it is the normal  version


your bet  will be to find a board who goes there, with an pc104 adapter and restart everything,   if you dont have  hidden problems elsewhere,
find the drivers  etc ....   

For a start  you should clone the drive before any attempt


If you search  BCM MX945  on fleabay,  you have some results of normal motherboards,  it could be a start  and try to build something  ou of them


The best and only one low priced 100$  is this : https://www.ebay.com/itm/255581180240?

If you search MX945  motherboards  you have more of them  starting at 50$


You are for the long run  if the motherboad is dead,  and a pci to pc104 adapter must be sold  $$

[ddrl46]

A while ago I had a Lecroy 44Xi-A which wouldn't boot either with similar symptons to your unit. Turned out to be a bad RAM stick in that case.

[zhongzuocheng520]

Thank you for your advice. I also searched for the motherboard. After maintenance, I found a problem with the original motherboard. The BIOS failed. I found a replacement code and wrote it in to start it. However, many settings are different, and failures can occur again after multiple starts. I don't know whether it is a program mismatch or a BIOS problem. It is difficult to solve without the original BIOS code.

[zhongzuocheng520]

Hello, my motherboard was repaired last night. It's a BIOS fault. I re burned the code. This is the website providing files. I hope it can help you：https://groups.io/g/LeCroyOwnersGroup/message/5694?p=%2C%2C%2C20%2C0%2C0%2C0%3A%3Arecentpostdate%2Fsticky%2C%2Cbios%2C20%2C2%2C20%2C82659882

[coromonadalix]

https://groups.io/g/LeCroyOwnersGroup/message/5694?


file zipped attached