Yes the chopper did blow up and I have since replaced it. So hopefully this is the last part that needs to be replaced!
Regards Rob > -----Original Message----- > From: Tony Duell <[email protected]> > Sent: 25 June 2023 17:52 > To: [email protected] > Cc: General Discussion: On-Topic and Off-Topic Posts > <[email protected]>; Brent Hilpert <[email protected]> > Subject: Re: [cctalk] Re: Rainbow H7842 PSU Fault > > On Sun, Jun 25, 2023 at 5:33 PM Rob Jarratt <[email protected]> > wrote: > > > > Thanks Tony. I removed the mains bridge rectifier and found it measured > short across two of its terminals, so I am ordering a replacement. I tested > the > PSU, without the mains bridge rectifier and without the diodes on the output > of the startup transformer. I got 24VAC on the output of the , the lamp > limiter > bulbs did not light and the fan in the power switch unit turned. So it looks > like > the startup transformer is actually OK. > > > > > It's possible that the rectifier just failed. Or it might have been damaged > because it had to pass too much current due to a problem in the main > chopper circuit. I would certainly check the chopper transistor for shorts > now. > > -tony
