It's a Chinese wallwart and into the place of square box in the schematic, there was a 8 pin DIP chip. However its only three pins are in use. Sorry that I forgot the IC label, I desoldered and throw away many months ago. Because it was damaged and some of the Chinese custom made parts are impossible to find around here.

Can you assume a 13001 or 13003 (or any 600V NPN) would work in the place of the component? Or what modification do I need to do?
EDIT: I found the IC label. It's HT1308. Some Chinese datasheet available too but hard to read.

 

I think it depends on the casing/footprints..

MJE13003 TO126 400V 1.5A
KSE13003 TO126
PHD13003C TO92 400V 1.5A
MJE13003-2 TO220 500V 3A

You can get those TO92 13003 from the CFL junk PCB. But I dont trust their quality.

I bought a tube of 13009 from Element 14 for repairing SMPS and they are in TO-220 casing.

Allen

 

Hi,
Did you see the circuit carefully? And can I use a high volts switching BJT NPN there in the place of the unknown IC?

 

The circuit showed error, I can't see it.

 

The circuit showed error, I can't see it.

Probably when you were clicking the circuit, I was replacing (deleting incorrect one and uploading corrected other) the schematic. Now maybe you can.

 

Dont think so. 13003 is just an NPN transistor. The 8-pin DIP is an IC which is much more complicated.

The common one is Viper22A which uses 4 pins as below..


Allen

 

I don't think it will be just a transistor. At first glance at the circuit I thought the lower winding was feedback to form an ascillator but then I noticed C3 and D2. (Note the high value of C3.) I think that winding , C3 and D2 generates a DC voltage that is compared with a reference voltage to control the output. This will not be as good as the normal method of monitoring the actual output and using an optical isolator to pass the feedback to the primary side.

Les.

 

I think it could be a N mosfet.

Below just a guessing and calculation, so you can using a Vds=400V or more to try, mostly the position is use an IC,

Vo(PP) = 220 Vac*1.414 =311 Vdc (The 2.2uF is too small, so here is a pulse DC)
Vgs = 311V(100K/(2.2M+100K))
= 311V(100K/2.3M)
= 311V*0.0435
= 13.5V (This Vgs matched the Vgs rating as <20V, but if adding a zener is better).

 

I think it could be a N mosfet.

Below just a guessing and calculation, so you can using a Vds=400V or more to try, mostly the position is use an IC,

Vo(PP) = 220 Vac*1.414 =311 Vdc (The 2.2uF is too small, so here is a pulse DC)
Vgs = 311V(100K/(2.2M+100K))
= 311V(100K/2.3M)
= 311V*0.0435
= 13.5V (This Vgs matched the Vgs rating as <20V, but if adding a zener is better).


View attachment 123053

Hi, I found the IC label, it's HT1308.

Hi Scott,
It seems that a Chinese company HOTCHIP has a Chinese version of its datasheet. Please do a search! Once I had saw same SMPS circuit (as I posted) in that Chinese datasheet too. I think you can read Chinese text.

 

Ok here goes the datasheet. It is an IC with over-voltage protection, over-current protection etc...

 

OK then one problem has been solved about unknown component. The main problem is I cannot get the unique parts. So I hope that making change in the circuit, I can get back the SMPS working again with high volts NPN. Once I tried a NPN directly and I think it was not working.

 

I think it could be a N mosfet.
View attachment 123053

Can you tell me one thing? What causes the MOSFET to turn off?

 

Can you tell me one thing? What causes the MOSFET to turn off?

No, because it is not just a bjt or mosfet, it just a tea time before find out the ic number and providing every kind of possibility and you just pointed out the blind point of my hypothesis, thanks

 

Hello,

You had a similar question some time ago:
https://forum.allaboutcircuits.com/threads/ht1308-chip-on-simple-cellphone-smps.119284/

In that thread the HT1308 chip is also mentioned by you.

Bertus

 

OK then one problem has been solved about unknown component. The main problem is I cannot get the unique parts. So I hope that making change in the circuit, I can get back the SMPS working again with high volts NPN. Once I tried a NPN directly and I think it was not working.

You may get the Vb too high from the voltage divider when you using an npn resistor.
If you using an n mosfet with Vds=400V and take the R2 away to try it and see how it's going.

 

Hi,
Did you see the circuit carefully? And can I use a high volts switching BJT NPN there in the place of the unknown IC?

That chip includes all the SMPSU regulator circuitry - a transistor doesn't.

Power Integrations do a range of 3-terminal switchers, but they're mostly TO220 package.

There are various industry standard chips in modified 8-DIL package - usually one or more pins are absent so the pin with the flyback pulses on it have more isolation from the other pins.

There's usually application notes with example circuits that might help match an equivalent - the divider resistors almost certainly set the output voltage, if they're not right for the replacement chip it could go bang.

 

Hello,

You had a similar question some time ago:
https://forum.allaboutcircuits.com/threads/ht1308-chip-on-simple-cellphone-smps.119284/

In that thread the HT1308 chip is also mentioned by you.

Bertus

Hi bertus,
Extremely so sorry that I forgot what I had asked 1.3 years ago. Maybe it's because I was unable to get 'medication for replacement' solution in that thread. Otherwise I would resurrect that thread again instead of creating new one.

No, because it is not just a bjt or mosfet, it just a tea time before find out the ic number and providing every kind of possibility and you just pointed out the blind point of my hypothesis, thanks

It looks like that one though: https://i.stack.imgur.com/AZZDK.png

OK I will see some cheap SMPS and will modify few circuit and will post here.

 

How big is your PCB. Does it able to accommodate those extra components?

Or...... you have different ideas.

Allen

 

How big is your PCB. Does it able to accommodate those extra components?

Or...... you have different ideas.

Allen

Ha ha, maybe he want to build a new one to see how it works .

 

Good question, I was feeling lazy to add other part in the board by seeing the board size. The PCB circuit is very small and compact.