ESR readings

No, that's too high. Expect to see around 0.3 ohms for a 'standard' cap, less than that for a low ESR type. However, I doubt that 1 to 1.5 ohms is bad enough yet to be stopping the supply from working, but replace them anyway.

Arfa

most of the supplys work, but the boostup converter is REAL weak at startup. they "grunt" before the bulb will start to grow brighter. normal ones dont do that, and I changed the caps, still "grunts" so im assuming worn out MOSFET in the boostup converter.

well 0.47 caps, 1uf caps, and 2.2 uf caps read about 5. at 50khz, new and old. so im assuming thats how it reads.

all 107 power supplys I have here, all 3 100uf caps are reading near 1 ohm, some a little over.

my new 100uf reads right at 0. (analog meter).

a more detailed explanation, it will strike the lamp, and the lamp will have a really dim arc. for a few seconds. then youll hear a small reeeeeek grunt sound like weak capacitors would cause in a normal power supply, but after that sound, the bulb snaps really bright and starts growing brighter like a normal lamp.

So i went right to the capacitors, they all read near 1 ohm or a little over for the 100uf rubycons. all my new ones read right at 0.

the main supply output filters read right near 0. so they are ok.

the rest is the mylar box caps. they are high enough value to be picked up by the meter, none or are open or shorted so im assuming worn out semiconductors from the heat. the astec supplys get really hot really fast. the magnateks dont do that.

I'm not really following that. What relevance does the readings of those other values have, in respect of the value you were asking about ? Your reading of " 0. " on an " analogue meter " is also confusing me. Zero is a short circuit. What sort of analogue meter are we talking here - ESR or ohms ? I have just checked a brand new out-of-the-drawer bog-standard 100uF @

25v, and on my Bob Parker meter, and it goes 0.3 ohms, which is in agreement with the front panel legend.

As I said before, 1 ohm plus for this value, is a little high. If I were repairing a SMPS, and found a cap of that value reading thus, I would feel inclined to replace it, as being " on the way out ", not because I would be particularly confident of it causing a problem. Although electrolytic caps are probably the single biggest source of trouble in switchers, there is a designed-in tolerance in most reputable designs, such that caps have to be significantly out of spec, before they start causing real problems. ( 5 or 6 ohms possibly for that value cap )

As far as your other belief ( further down the thread ) that " worn out " semiconductors - MOSFETs - are to blame, I think that the chances of that lie somewhere between slim and zero. Whilst I have had bipolar transistors that have gone noisy, and some that have gone low gain, and more than a few that have gone leaky over the years, by far the most common failure mode for semiconductors, and particularly power MOSFETs, is catastrophic junction failure e.g. short circuit. I cannot think of a failure mode that might be considered as " worn out ".

Depending on the topology employed in these supplies - self oscillating primary, IC oscillator and control primary etc - if caps are not to blame for the sluggish startup, then I would be inclined to start looking for resistors that have gone high. Possibly a startup resistor on the primary side, or a current sense resistor on the secondary side. Good luck with them, and do be careful to observe the highly necessary safety precautions for working on line powered switchers.

Arfa

sounds normal.

NT

LOL i doubt it. i have a good supply that starts up right away.

im gonna take the other persons advice, i think the resistors are going out of tolerance on the power factor controler. now i have to find a magnafying glass to read the number on these SMD resistors.

I dont have a bob parker or a dick smith meter, I just got an average MCM tenma run of the mill analog ESR meter. its hard to read down to the decimal points, but it gives you a general idea at least. :) I dont have an ESR chart to follow, im new to this ESR stuff. all my power supplies that have

100uf caps are all reading right on 1ohm. some read 2 ohms, and i know thats bad. I just didnt know what was good and what was bad, again i dont have an ESR chart and im new to ESR.

as far as sluggish startup, there is 2 parts to this supply, well actually

3, but 2 are most important.

there is a VIPER100A switcher circuit that runs the transformer that produces the 5, 12, 3.3, -8.5 volts DC. That works fine.

its the 120 to 400v boostup thats being sluggish to start. as soon as the bulb starts, a normal power supply the boost would startup instantly.

these few I got here are a little sluggish than others. some boost converters dont start at all, and im beginning to go toward your resistor theory. becuase the mosfet, and the power factor controlle rIC that runs the boostup test fine.

there is only 1 cap in the boostup converter besides the tank cap. replaced the cap in the feedback return, and didnt help much. its a little more regulated now :-) i guess thats a plus.