HP Z800 power supply [FIXED] - query re cap and fan replacement - Page 1
Forum section: electronics / repair

author: Lorenzo_1
author_rank: Regular Contributor
timestamp: May 28, 2018, 02:48:40 am
content: My HP Z800 workstation failed power up after a shutdown - power switch flashes red 4x and beeps, showing power supply overload. Supply is 850W and puts out multiple 12V lines and 1x 5V line (photos attached for those interested). No schematic available, but when I stripped it down there was an obviously bulging cap (470uF 35V). Didn't have one handy but replaced temporarily with a Nichicon 1000uF 50V cap and it's now working fine again.Will this cap suffice longer-term or should I replace with the correct value/same cap?Original is an LTEC LZG series ultra-low impedance cap -http://www.compostar.com/Ltec/LZG.pdf.Replacement a Nichicon VZ series -http://products.nichicon.co.jp/en/pdf/XJA043/e-vz.pdf.Both are 105C rated. I'm unsure how critical the cap parameters might be in this situation. Seems the Ltec is still available.The supply has two Adda fans fitted. I can numbers of these specific fans on eBay from Chinese suppliers at low price and am wary as to whether they're genuine or not. Would I be better to buy higher price non-Adda fans from reliable suppliers (at considerably higher prices)? The spec is straightforward - Adda datasheet indicates 80x80x25mm 12V 0.21A (cf 0.26A on actual fan), 48CFM, 3600rpm - which should be an easy spec to meet.

author: Zucca
author_rank: Unknown
timestamp: May 28, 2018, 07:43:22 am
content: As long your C voltage is bigger than the original one you are safe. The C value in filter elco is mostly also not critical, the bigger the better (normally is the size/space on the board the limit)I would order new proper caps (as you find out, Nichicon are a good choice) and replace all of them on the board, you will sleep well for the next 5-7 years.Quote from: Lorenzo_1 on May 28, 2018, 02:48:40 amIn the past I spent more on fans just because they were much more SILENT than the older ones. I did not regreat my choice, and when I hear just a little of "sssssss" everytime the fan is working, I think "good choice, well spent money".

author: Lorenzo_1
author_rank: Regular Contributor
timestamp: May 31, 2018, 09:48:54 pm
content: Hi Zucca. Thks for the reply. I think I will do a pre-emptive replacement of the secondary caps and fans - and buy quality fans. So far the supply is working fine with this temporary fix.

author: LeonR
author_rank: Regular Contributor
timestamp: June 01, 2018, 04:34:58 am
content: ADDA is a reputable fan manufacturer. There are more silent options from them too, just try to match (or surpass) the CFM/static pressure on the new ones.

author: Lorenzo_1
author_rank: Regular Contributor
timestamp: June 01, 2018, 01:39:53 pm
content: Yes, I am confident ADDA fans are good quality. However, not sure I should trust China-based suppliers of very cheap fans sold as ADDA. They look genuine but are they counterfeits, factory rejects, or good quality at super competitive prices? Given how much I rely on this Z800 I think I should probably stick with a reputable local supplier and pay the premium - unless someone here has had good experience with China-sourced ADDAs.