Hi folks;
Again and again I see people posting here with various problems which would send me straight to the scope probe. Does anyone use these things anymore or what ? When you got immediate shutdown for example, what I do is scope the HOT. Does anyone else do this ?
They'll disable shutdown, risk blowing the power supply or worse, check
50 voltages and resistances or so, when all they needed was a scope.If you don't have a scope that'll get you to 200V/div, scope the line feeding the 200V recifier, or you can just crank the scope down to about 5V/div or so and just get the probe near the flyback.
OK an old Mits RPTV comes in, the one with 2 SMPSes on a board mounted to the side (like a vs 4506 etc.)
Clicks on, clicks off. I put the probe near the fly, nothing, I put it near each of the SMPS transformers and one of them is running a very short pulse width, pull it, leave it plugged in and quick check for shorts on the output lines, none, OK a few caps and an STR-S6301. Fires up.
If I have a good waveform at the fly I go to the vertical, thumb on probe and adjust timing until I can see the 60 Hz. Outer yellow and green yoke lines, and bet it ain't there, or I could get a bad waveform at the fly and then it's time to disconnect the HV, and then the yokes. (in that order BTW). If I get a good waveform at the fly and vertical is working I go to the 130V line and set the scope to 50V/div. Center the trace on a line and watch it like a hawk as you hit the power. You can plainly see if it goes up three divisions, at that point it gets an SE130. If it levels off at what looks like 130 volts, I'll switch to
20V/div and make sure. If it is indeed in regulation I go to the ABL line.After ALL that I MIGHT disable the shutdown if I have nowhere else to go. Why don't others do it like this. If you're familiar with that type of set, is there a better or faster way ? If so tell us. This is by no means the same for every set of course.
The main thing is, I see scopes just collect dust in shops until I get there, sometimes. How many parts have been replaced needlessly ?
Perhaps alot of techs need a scope class or something ?
JURB