Re: Mystery SMPS IC Follow Up

[Andrew Mawson]

>>

>>> That looks like 32KHz/60Hz >>> >>> i.e. the most common 640×480 standard VGA mode. >>> >>> >>> >> >>For inspiration :) >> >> >> > > >Thanks Adrian, interesting stuff you've been feeding me ! > >Andrew

In response to my original question some kind person sent me a link to the TDA4601 9 pin smps chip, sorry I didn't note who.

But thanks you for that - in the application notes for that chip was a circuit almost identical to that in the monitor I was trying to repair. From that the repair is now completed and we are back up and running - so THANK YOU !

AWEM

[fred]

In article , Andrew Mawson writes

And the fault was . . . . . .

[Andrew Mawson]

A short circuit capacitor across the 35v rail in the line oscillator circuit. Due to the high load the smps never started up

AWEM

[fred]

In article , Andrew Mawson writes

Thanks Andrew, others have previously reported weird and unexpected failure modes in the past that I wouldn't have thought to test, hence my curiosity.

[The Natural Philosopher]

when in doubt change ALL the electrolytics.

[Andrew Gabriel]

+1

I've had several where the output caps drop in value, but not had one where they've shorted out.

[Mike Tomlinson]

En el artículo , Andrew Gabriel escribió:

Yes, 'lytics usually go low ESR but I've never seen a shorted one. Had a shorted tantalum cap once, but that was many years ago.

[Andrew Mawson]

Oddly recently I've had several go s/c so I really should have thought about it. I had two go s/c quite dramatically in a high power servo amplifier on my CNC lathe - 100 amp peak current jobby. They were on the pre-driver board and made a noise like a wire fuse blowing. Turned out they'd taken a pcb track with them vapourising the track. Cause was a short circuit in the 'H Bridge' power circuit - this is an integrated six transistor 'chunk' made by Fuji (6DI75AH-050) oddly rated at 75 amps.

AWEM