Electronics > Repair

Lecroy Waverunner 64Xi-A no power

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analogRF:
the orange wires are the +3.3V in question

analogRF:
I believe to some extent (maybe to a large extent) this PSU could be similar to Cherokee SP551 for which the schematics are available.
specially the output circuits looks similar to me. that PSU doesnt have the daughter boards and I think everything was laid out on two boards
so the big difference could be that they just redesigned it with daughter boards...at least the output circuits looks similar at first glance to what I have

EDIT: by the way this SP551 PSU is used in the old Lecroy Waverunner 6000A series

coromonadalix:
there was a thread

https://www.eevblog.com/forum/repair/lecroy-power-supply-(cherokee-lineage-power-sp651)/

and check the attached pdf  pinout draft from another place
https://groups.io/g/LeCroyOwnersGroup/topic/wavesurfer_44mxs_b/7707066

warning PLS DO CHECK if it somewhat fits ?

analogRF:

--- Quote from: coromonadalix on November 28, 2024, 03:15:35 pm ---there was a thread

https://www.eevblog.com/forum/repair/lecroy-power-supply-(cherokee-lineage-power-sp651)/

and check the attached pdf  pinout draft from another place
https://groups.io/g/LeCroyOwnersGroup/topic/wavesurfer_44mxs_b/7707066

PLS DO CHECK

--- End quote ---

thanks
I have seen that thread and the document.
right now one of the two double diodes on the 3.3V rectifier read odd in circuit so I have to desolder it and see how it is

yes there is a green wire on teh 22 pin J3 and also the usual green wire on ATX connector (that goes to the PC motherboard and is directly traced back to the power on switch) they are not connected. So the person who did that pinout thought that the green wire must also be another power on signal coming from acq board and I suspect that too and I am inclined to ground  it (as well as grounding the usual PS_ON on the ATX) so maybe that will start the supply. Someone on groups.io had aleady said that two power on signals are diode OR'ed on the PSU and both need to be grounded to turn it on....
I'll trace the circuit before just blindly grounding any green wire that I see!

analogRF:
you see this!
this is insane. those diodes and mosfets are not "screwed" to the heatsink. they are "punched" onto the damn thing.
no way to take them out unless I take the whole thing out and the board takes in so much heat... |O |O |O :palm: :palm:
even then it is hard to replace any of them. I dont have the tool to punch them back in I have to screw it but with just the right size...then dont have a tap... :palm:
whoever designed this thing was insane
first the disassembly is so complicated and you have to disassmble the whole scope to the last wire and screw to get here...then this  >:( >:( >:(

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