Diawa 606a PSU failed, need help

[VK2KRR]

This morning my Diawa 606a switch mode power supply unit failed, for no apparant reason. I use this to power my 2m or 70cm PA's. Its rated to 60 Amps, 12V.
I've had it for a fair while, probably 9 years. It only ever gets switched on when I need to use the PA's, so in reality, as a time percentage, its not used much at all. Ive never had an issue with it.

This morning I used it to work VK5PJ, VK5AKK, VK5GF, VK3XPT, VK3XPD, VK3AHT, VK3ALB. Im fairly sure it was still on when I heard VK5ZLT calling CQ, and I thought the supply was off, and so I accidently switched it off for maybe 2 seconds, then realising, I switched it back on. And there was nothing when I switched it back on. This was right about 15 mins before the start of the field day

When its switched off it usually takes 5 or 6 seconds before it fully shuts down, it must be bleeding off charge or something. So im thinking because I switched it off and then switched it back on before the 5 or 6 second shut down time that this has caused something to not be happy and now when its switched on nothing at all happens.

Would anyone have any ideas on what may have happened and what should I look for ?

I've so far pulled the cover off and for starters it was full of dust, which Ive blown out now with an air compressor.
No change.

In the manual, it indicates there should be an AC fuse on the rear panel, but I cant see that anywhere.

Ive checked the on off switch for continuity, that works OK.

Ive checked the power cord pins for continuity to the plugs on the rear of the switch, and that seems OK.

Visually I cant see any issues.

Im about to unbolt the whole circuit board from the chassis so I can check underneath it.

[VK2KRR]

I see some pins labled TP 1 to TP5 in different locations, would they be Test Points ?

[ZL1UJG]

Sometimes the fuseholder is part of the IEC socket, have a closer look, it might be a little slot underneath.
Switching off and on quickly , may have crowbared the PSU in someway. So there may be that fuse and/or another one gone

[VK2KRR]

Where the IEC socket is, it goes into a metal box which is solder sealed, its got a few vent holes in it but I cant see anything resembling a fuse in there. But if there was and it was blown it should be OC coming in, but it seems to have continuity through there.

I did find a disc capacitor that had been folded over on the board and was being crushed by a bank of cooling fins. I've unscrewed that and stood it back upright, I dont really think that would be the problem though

[VK2DVZ]

IEC fused sockets have an M205 fuse installed - prize off fuse cover to check.

[VK2KRR]

OK Ross

[VK2KRR]

Ross,

I found the fuse, it was hidden in a little slide out drawer holder. It tests fine

[VK2KRR]

Some further desperate testing with a screw driver handle has led me to believe that the issue is with a faulty relay soldered to the main board, marked as being K1 on the board. Directly behind the voltage/current meter.

With the power switch on, Ive given the relay box a number of solid taps with the screw driver handle and the fan powered up, lights came on as they should. Reading 13.8V on the terminals.

Upon shutting down and trying to restart, it again would not start up until tapped with the screw driver. It appears to shut down OK with a good loud click, but trying to start up there is nothing until its helped along.

Looks like I may need to find a replacement component.