2015-11-01 17:35 GMT+01:00 Robert Jarratt <[email protected]>:
> > > > > > Maybe you can publish your schematic somwhere. It is much easier to > > > > come > > > up > > > > with ideas to pin point problems if we all view the same schematic. > > > > I > > > think it > > > > would be possible to identify the problem without comparing the two > > > > PSUs > > > at > > > > least in this case where there is some kind of fundamental problem. > > > > > > I do intend to publish the schematics, but right now I am pretty sure > > > they > > > are: > > > > > > a) full of mistakes > > > b) not drawn logically > > > c) there are a couple of areas I couldn't trace without major surgery > > > on the board. > > > > > > > Well. I guess that anything is better than nothing. > > > > > Here is a link to what I have now http://1drv.ms/1KQkTBp > > There are Eagle sch files, and PNG files for those who do not have Eagle. > I took a quick look at the schematics and I had hard times following the schematics, but I guess I asked for it. Anyway. I think that the signal is produced somewhere behind the transformer T301 and then passes through a number of driver stages (Q405 and Q408) until it gets to the Q301. You could check the signal on T301 and onwards. The designation for the connector of the small boards are all X1 while there X1, X2, X3 mentioned on one schematic so I am a little bit confused. Then there are four small boards which presumably have Xn connectors but I can only find three in your schematics. But this is maybe a result of the fact the schematics are incomplete or me misunderstanding something. The circuitry C403 and R407 doesn't make sense to me. It has to be a drawing mistake. Maybe it is a good idea to to focus on one area and to make that part of the schematic complete. Like the part surrounding the main switch transistor. Then try to follow the signal back through T301 and trace that part out. If the PWM signal is produced on the secondary side then there has to be some small PSU providing power to this circuitry at startup so that the PSU can bootstrap. But I cannot see where this is. Good Luck! /Mattis > > Regards > > Rob > >
