Testing TOP246 top 255

Hello everyone,

I want to know if there are methods to test top255yn or top246yn integration power controllers.
I draw your attention that I used this circuit but I could not measure 5.8 V in the pin C.


cordially

It looks as though half of your schematic is missing. Probably voltage regulation? It carries a feedback voltage (5.8V is the figure in your post) back to the IC

By the way are you using a snubber network? Is it different from that which is crossed out in your image?

Thank you, in the editing I canceled the outputs and the loop back, I only wanted to test the IC top 255yn because I read in his manual that the pin c at first time is loaded through the pin D.
However in my case I can not get it anymore knowing that I have already got this value with other top255yn regulator so I think the problem is in these regulators may be who they are damaged.
That's why I wanted to look for a diagram to test them.

Regarding the components that are lying I did not use them.

Hi ,
So i’m using this circuit. With out a feedback just to testing the top 246 Y.
So when I measured to tension in the auxiliary (4,5) I find 12 V, knowing that the C pine at what I believe should not exceed 5.8 V, I'm afraid to connect it with this pine.
So what do you think.

To test the IC I would try these steps:

* Use a power supply of the minimum recommended voltage.
* Create a resistive substitute for the transformer.
* Apply a feedback voltage to pin C.
* Test whether pin D provides an On-and-Off path to ground.

To test the remainder of the circuit, you can make an oscillator to turn the transformer On and Off. Attach a resistive load to a secondary. Observe output waveforms to see transformer performance. (Your schematic appears to have no load attached to the output. It may require a load in order to operate properly.)

The transformer is able to produce a high-voltage spike when current is abruptly stopped. The spike can be hundreds of volts. Normally the snubber network absorbs the spike. But since your schematic has the snubber network crossed out, then there's a chance your IC was exposed to a high-voltage spike within the first one or two cycles of use. It may be ruined.

Sometimes I do an ohmmeter check on an IC. From one pin to another. Although there are dozens of possible combinations, I don't perform all of them. If the IC is good then it shows different ohm readings between its various pins. But if ohm readings are all the same, then it tells me the IC probably has fused innards, meaning it is destroyed.

I prefer to do such ohm tests at the highest ohm range (x 1k). I prefer to use my analog VOM which runs from a 1.5V battery. My digital meters contain a 9V battery and IC's don't always tolerate such a voltage difference applied to its pins.

thanks for your response but i have some questions :

Sorry, I don't know how this control IC operates and I can only suggest a few general ideas. A design team would have a supply of new chips on hand. You're trying to be a one-man design team learning with one IC. And that IC may be broken.

With flybacks it is common to create a feedback voltage via optocoupler. Therefore a suitable tactic may be to install a variable resistor at pin C, to pull down the voltage which is already coming from that pin.

It's possible your transformer requires loads on the secondary windings, in order to allow normal flux building and collapsing. A 100 ohm resistor may be sufficient load.

Do you have an oscilloscope to verify proper waveforms across pins 4 & 5 on your transformer?

Typical flyback duty cycle is 50 percent. By making a pulsed DC oscillator, you might get the flyback to operate. Start with a low supply voltage. Monitor component temperatures. Ramp up the supply voltage. When you see proper waveforms and proper polarities then you can attach diodes and capacitors for output stages.

Hi,

1-how i can Apply a feedback voltage to pin C.

Click to expand...

Read the datasheet.
Without feedback there is no ouptut voltage regulation. This means: no upper limit. In worst case this could cause a too high voltage caused by the transformer that may kill some electronic parts.

Klaus

hi apply the feedback to the pin c but always i have a bad result and the regulteur top switch 246 yn do'ont work


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hello thank's,

the problem when i connect the feedback i still measured this signal in the primary View attachment SDS00023.BMP

and in the pin c that's what i measured View attachment SDS00021.BMP