4 Feb
2022
4 Feb
'22
8:03 a.m.
On Thu, 3 Feb 2022, Peter Coghlan via cctalk wrote:
Today I finally managed to check it out. The ceramic
F4A mains input fuse
beside the power switch on the back panel had blown. When I opened it up,
I found a POWER-ONE MAP80-4000 power supply. The main chopper transistor
labelled Q1 on the PCB is almost a dead short. It is a large plastic
packaged FET mounted on a piece of aluminium which is in turn screwed to
the case for heatsinking. Unfortunately, there are no markings on it so
I have no idea what to replace it with :-(
As Q1 is shorted across all three terminals, whatever drives it may be
damaged too :-(
After finding screw heads hidden under the label, I managed to extract
the PCB from the case and found some corrosion underneath, possibly from
leaking electrolytic capacitors :-(
This PSU seems to have been used across various Cisco devices and I had
one fail several years ago in a WS-C1202 Ethernet/FDDI switch, also having
suffered from leaking caps. Back then RS still had it in stock at a hefty
price of ?489.60: <https://uk.rs-online.com/web/p/products/8338173/>, so I
chose to recap the failed one and thanfully it has continued working ever
since. You may try to enquire with the manufacturer.
Good luck with bringing yours back to life!
FWIW,
Maciej