Hello readers. In October 2014, I asked for advice on this forum regarding the faulty switching power supply AVAIR 1030 HAM. Mainly, I was looking for the schematic of this power supply. I couldn't obtain it, so the power supply remained non-functional on the shelf.
In short, what was the cause of the failure. I used it at home QTH to power the IC910. Everything worked until the moment I wanted to use the power supply at the cottage, where I don't have a power grid. I have a 2.5kW four-stroke gasoline generator there. I use it without problems to power the refrigerator, rotavator, lawnmower, and other appliances. When I connected the AVAIR power supply to it, it just blinked and remained 'silent'. Even after bringing it home and connecting it to the grid, the power supply did not start. I decided, since I didn't have a schematic, that I would go about it by gradually unsoldering the semiconductorcomponents and measuring them. On the main board, where the power components are, everything was fine. I unsoldered the PCB board from the main board, which is soldered perpendicularly to the main board using 6 pins. This PCB measures about 5 x 7cm. It contains 3 transistors, a few resistors, capacitors, and a 0.1A glass fuse. The first look after removal showed a burned fuse. All transistors either had a breakthrough between the electrodes or were broken. I found replacements. I replaced the power SC4977 with BUV46A. I replaced the complementary pair 2SA1020L-PNP and C1815L NPN witha pair of BC640 and BC639. After the replacement, the power supply woke up and works without problems. I hope this detailed description may help someone who finds themselves in a similar situation. 73. Igor