toggle quoted message
Show quoted text
On Fri, Apr 26, 2019 at 5:51 AM Lorenzo <ltcrocs@...> wrote:
Hi Roger. Reminded myself how to add photos and have uploaded three
tonight that should help answer your queries. They're under a new album
with the same name as this post thread. The 'white' screenshot is an old
one done when I was digging into the problem months ago. Shows the spiking
on U1624 pin 3 as the -5V supply starts to come up and then tracks upwards
towards GND as it fails/shorts. Also shows +5V supply that also comes into
U1624 Pin 3. The 'yellow' ones I did tonight - show voltage directly
across CR1958 using my differential probe, and activity on BAL node, LIM
node and HV node. LIM node shows no -ve excursions so looks OK. HV node
also appears OK - these were done with comb U3 connected, so HV active.
CR1958 is conducting as the -5V supply fails and doubtless explains the
shutdown. I've tested all the resistors and supply voltages going to the
balance node - all look good. All the other LV supplies behave fine and
rise or fall uniformly towards their final values before the inverter shuts
down - and pretty much in proportion to one another. I've done lots of
testing with U3 in as well as with U3 out. Perhaps this will suggest some
further tests I should focus on.
I also checked on the current drain readings I took last night with scope
off - but this time with U3 connected. Made no difference at all to the
readings.
