test active pfc power with lamp test

[khelane]

Hello
I have a big problem and that is that in some cases when repairing active pfc power supplies I cannot work with a test lamp. I can only get help with 5 volts standby and for starting and starting I have to work without a lamp and this way there is a possibility of parts exploding and other parts being added.
Sometimes with a multimeter test the problems can be reduced to some extent, but I had several cases that had to be tested on and online and recently two varistors exploded. They had terrible resistance because the power supplies were over 800 watts.
Is there a way to safely test these active pfc power supplies?
Thank you

[stj]

use a bigger lamp, i use a 400W halogen floodlamp
another guy on the forum uses a water heater or a toaster or something like that!!

[khelane]

tnx

[CapLeaker]

Or multiple incandescent lamps to increase wattage.

[khelane]

Thank you for your advice.
The main problem is that when I turn on the device with the test lamp, the lamp quickly turns off and on, and I don't know if there is a connection in the circuit or not. When the hot part has a connection, the lamp turns on completely, but after testing and troubleshooting, I want to start the device with the test lamp, it turns off and on quickly, and I'm afraid that if I turn on the test lamp, it will explode. A few days ago, I repaired a device. The lamp blinked or turned on and off during startup and startup. When I started it with the main power, the varistor exploded.
In normal power supplies, the test lamp has no problem with starting the power and turning on, but in active pfc power supplies, when I turn it on with the test lamp, if there is a connection in the hot part, the lamp turns on completely as before, but when there is no connection or maybe a component has a leak, after turning on and testing the output voltages, the test lamp quickly turns off and on. Is this turning on and off my problem?

[harp]

First use a 100w test lamp, to see if there is short. If you see the simptoms of apfc (clearly blinking lamp), use a regular toaster (700w), and confirm stable outputs, input voltages, etc... sucessful repair. When is all ok, power on directly from mains with armor and finger crosed... Electronic can explode at any time, so dont be worry about that.

[CapLeaker]

Also you shouldn’t test an active PFC PSU with the test lamp all the time. The test lamp is to limit the current. Problem with that is it makes the PFC work harder then it drops out, starts again… hence the blinking. What kind of wattage on the incandescent light bulb are you using?

[momaka]

use a bigger lamp, i use a 400W halogen floodlamp
another guy on the forum uses a water heater or a toaster or something like that!!

Presume you were talking about me.

Yes, I actually use both - 450W dishwasher heating element for "lighter" loads and a 700W/1400W mini toaster oven, with the 700W setting being my "medium power" level, and 1400W for when I actually want to test with a fairly "large" load on the PSU (100-120 Watts or less, and I'll explain why.) The idea is to keep the load at less 10% of the heating element's rating so that the voltage going to the PSU doesn't fall too much (below 100V), as otherwise APFC PSUs will turn off below that... so for a 1 kW or more heating element, 100-120 Watts is about the max you can do.

I DO like your idea of using high-power halogen lamps, though - they have a very low cold resistance and as such are less likely to cause issues with APFC circuits (I think!)

Also you shouldn't test an active PFC PSU with the test lamp all the time. The test lamp is to limit the current. Problem with that is it makes the PFC work harder then it drops out, starts again… hence the blinking.

Indeed.
Though for those of us living in countries with 220/230/240V AC, we can have the AC voltage drop a lot more from the series light bulb or heating element before the PSU refuses to turn on.
On that note, it would help if some of new member here actually bother to put their country in their profile name, so that way we can know what AC voltage they have available. (Seriously, no one will be that desperate to come and find you if you post what country you live in. )

[khelane]

Do you mean after starting with a 100-watt bulb, if the bulb starts to flicker, should I turn it off and instead of a 100-watt bulb, should I use a 700-watt toaster or a 400-watt halogen? And then turn on the power supply? And test the voltage of the power supply? In the end, I am in a place where it is very difficult for me to find a part. I want to minimize the damage.

[petehall347]

use a regular toaster (700w), and confirm stable outputs, input voltages, etc... sucessful repair. When is all ok, power on directly from mains with armor and finger crosed... Electronic can explode at any time, so dont be worry about that.

if it makes toast then its time to stop and eat whilst wondering what to do next .