Sick Lecroy PSU (WaveSurfer XS-A) - Page 1
Forum section: electronics / testgear

author: darkstar49
author_rank: Frequent Contributor
timestamp: August 31, 2017, 04:05:42 pm
content: Hello,just received a Lecroy 44 XS-A... the drive was corrupted beyond imagination... so I thought let's install a new hard drive and make a fresh XP & DSO install... so far so good... but now that I've worked a bit with it, I got it... the PSU overheats and shutdowns/resets randomly after a while (not long ! 2-5 minutes at most...), hence the completely corrupted drive...Being a total ignorant about PSU's, I'd like to know what kind of failure(s) can cause a PSU to overheat (but still work fine, seemingly, for a while...)...I'll try to find out what Lecroy requests for a PSU swap, but that's probably not going to please me...Any hints (more than) welcome... !

author: lukier
author_rank: Unknown
timestamp: August 31, 2017, 04:22:44 pm
content: Quote from: darkstar49 on August 31, 2017, 04:05:42 pmI don't know how much corrupted is "beyond imagination", but I hope you managed to recover the calibration files out of the D:\ partition. When I got my WaveRunner 6100A the HDD was also very sick, but not completely unresponsive so, fortunately, I managed to grab these files.Quote from: darkstar49 on August 31, 2017, 04:05:42 pmI don't have much experience here either, but what helped me a lot in some recent repairs was the thermal camera. Surprisingly useful tool. Come to think of it I need to look at my WaveRunner's PSU as well. It works alright, the voltages are as specified, but when in standby there is something like faint fast-clicking/buzzing noise, somewhere around the input X2 caps, inrush relay and there are two 1-2W resistors back to back (by proximity I would guess it is PFC) that get immediately very hot (>70 deg C) - all this in standby! Doesn't look right, it should be super cool.

author: darkstar49
author_rank: Frequent Contributor
timestamp: August 31, 2017, 05:22:01 pm
content: yep, got a backup of the USERDATA partition... it was the system partition that suffered apparently most from the recurrent resets...The only thermal camera I have (currently... I also have a Ti25 in pieces in a drawer, but chances are low to 'rebuild' it....) is a Flir One for my iPhone... Not a bad idea, indeed... a problem will probably be to remove and open the PSU (looks pretty compact !), while keeping it going...

author: lukier
author_rank: Unknown
timestamp: August 31, 2017, 05:44:21 pm
content: Quote from: darkstar49 on August 31, 2017, 05:22:01 pmQuote from: darkstar49 on August 31, 2017, 05:22:01 pmWell might be hard to replicate the fault without the scope HW connected, but you can always power an ATX PSU on the bench by shorting the green wire. Maybe this alone could help. If not try loading rails one by one if you have a DC load (and if you have a multi-channel Chroma beast of a DC load then you can do the proper testing) While powered at idle you can measure the voltages and hope nothing is too high that could fry the scope

author: darkstar49
author_rank: Frequent Contributor
timestamp: August 31, 2017, 07:12:22 pm
content: No DC load at all... certainly something for one of the next Xmas wishlists... ;-But I don't mind taking the beast apart, I wanted to check for the possibility of replacing the MB with something more powerful anyway...I just need to put some order on my desk... I've got 2 other scopes in pieces, as well as 2 Fluke dmm's... I feel it's somehow cleanup time, otherwise, I'll end up with AgiCroy and LeGilent scopes...

author: darkstar49
author_rank: Frequent Contributor
timestamp: September 01, 2017, 04:26:38 pm
content: This endeavour will probably have to wait a bit... Lecroy just proposed to send me a new PSU for 250 USD...I love Lecroy !!!!!No other brand has that level of long-term support and flexibility... (maybe related to their still 'human' company size ?)I once got a quote from Tektronix for a PSU for a DPO4034: 1300 USD, and it could only be replaced within their facilities... cost: around 2000 USD !!! And the Artesyn PSU for the Tek is a 200W open-frame PSU, while that of the WaveSurfer (also from a higher end brand...) is a fully-framed PSU of (I think) 750W... where's the error?