The guys at RICM have seen a problem with these supplies that if the output cap is bad it won't start switching properly. It goes into a mode where it acts as a linear regulator. As far as I remember they the a spice simulation that also indicated this when the output cap had low capacitance.
Do you see switch pulses coming out of the 723? As suggested earlier it is a good idea to have a real AC source that is not going to fold back when you put some load on to the H745. Does it switch correctly with less load? /Mattis Den tors 27 jan. 2022 kl 00:42 skrev Rob Jarratt via cctalk < [email protected]>: > I am trying to test a couple of H745 regulators with a DC bench PSU and I > am > having some problems with testing them. > > > > My bench PSU is a twin unit so I can supply the +15V required as well as > the > "AC" input using 20VDC from the other half of the bench PSU. The problem is > that I don't think the bench PSU can supply enough startup current to allow > the regulator to run. It can only supply 5A max. > > > > I have seen with the H744s that if I put too big a load on them, then they > can't start because of the heavy startup current required. I can start them > with a lower load and then add load once the regulator is running without > breaching the current limit of the PSU. > > > > With the H745s I have tried reducing the load to see if I can get them to > start, but a 10R load appears to be too much and the regulators draw the > full 5A without outputting -15V. > > > > I have two H745s, both exhibit the same behaviour. I suppose they could > both > have the same fault, but I am inclined to think that perhaps they need a > higher startup current than I can supply. Can anyone confirm this? > > > > Thanks > > > > Rob > >
