[cctalk] Re: Rainbow H7842 PSU Fault

[Rob Jarratt via cctalk]

> -----Original Message-----
> From: Jon Elson via cctalk <cctalk@classiccmp.org>
> Sent: 25 June 2023 16:24
> To: Rob Jarratt via cctalk <cctalk@classiccmp.org>
> Cc: Jon Elson <el...@pico-systems.com>
> Subject: [cctalk] Re: Rainbow H7842 PSU Fault
> 
> On 6/25/23 07:36, Rob Jarratt via cctalk wrote:
> > This made me suspect that the startup transformer may have been
> > damaged. So I checked the output of the startup transformer. On the
> > bad PSU this was about 2.4VAC, while on the working one it was about
> > 12VAC. I lifted all 4 of the diodes connected to the startup transformer and
> they all tested OK.
> >
> Well, apply current-limited 12 V DC to the output of the bridge rectifier and
> see what current it draws.
> 
> Could be a failed capacitor or regulator, or something downstream of the
> regulator that has failed.

If you mean the 7812 on PSU Sheet 1 then I believe it is fine as I have already 
tested it with a bench PSU supplying it with 15VDC and it works fine.

> 
> (Maybe you have already checked this.)
> 
> Jon