MOFFET Driver IC?

Thread Starter

hazim

Joined Jan 3, 2008
419
Hi.

As usual, I'm repairing something and needs your help :).
It's an smps type 1100W inverter. It had many problems and bad parts that I've fixed. Now I can measure high DC voltage at the HV capacitors, but there is no AC output. I measured the gate voltages of the high voltage MOSFETs using an oscilloscope and found no voltage... The ICs numbers' are erased and can't know them but the oscillator or HV MOSFET gate driver circuit is is connected with an IC as shown in the picture. I think this IC is something like a MOSFET driver or PWM IC. To know what it is let us first find a PWM/MOSFET driver 14-DIP IC with two outputs at pins 10 and 11. I didn't drew the whole circuit in that area...

NOTE: There is a mistake in the picture, it is a 14-pin IC and not 16 and the outputs are 10 and 11.

Any help, idea or suggestion is strongly appreciated.

Hazim

 

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praondevou

Joined Jul 9, 2011
2,942
Post a picture of the PCB please.

Also, try to find out if it's a driver or a controller. Are there any other IC's on the board? If it's a driver and you do not measure anything at the outputs 10 and 11, you could still measure pulses at the drivers input. If it's a PWM controller you may find a clock voltage somewhere.

You said you measured the voltage on the gates. Did you measure at the gates or at the outputs 10 and 11 or both?

Try to find out where the power supply is connected to the IC.

Post all details you find like clock pulse frequency, IC power supply etc.
 

Thread Starter

hazim

Joined Jan 3, 2008
419
Actually the IC broke when I was desoldering it and taking it out... so I can no more test it. I measured the voltage at the gates and not outputs 10 and 11.
The MOSFETs gates and oscillating circuit is connected only to that IC by pins 10 and 11. There is many ICs on the PCB and it's a big board full of parts... I should first find the Vcc and GND of the IC and test the voltage on it, I tried to find that pins but failed.

 

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SgtWookie

Joined Jul 17, 2007
22,210
10 and 11? You said before it was 11 and 12. Thanks, I wasted a good hour trying to find a PWM controller IC with outputs on 11 and 12.
 

praondevou

Joined Jul 9, 2011
2,942
Looks like a driver to me.

Please take a better picture of the IC and adjacent components on TOP and BOTTOM layer.

What are the other two small ICs? (8-pin DIP)

Is there anything connected from the white connector directly to the broken IC?

The power supply is probably connected to some bypass caps near the IC.

GND is the gate pulse reference, at least on the output part, so there is at least two traces going directly from IC output to the MOSFET gate drive transistors, according to your diagram the KSP44/2907.
Thinking again, there should actually be three traces connected directly between IC and these transistors, +, GND and gate pulse...
 
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praondevou

Joined Jul 9, 2011
2,942
It seems you tried to desolder it heating up all pins and then lifting it with a screwdriver.

If you don't care about the IC, cut all the pins near the IC body and then desolder pin after pin.
If you do care about the IC, use a desoldering pump to free each pin from solder, until it moves freely in the hole, you can apply more solder beforehand.
You can also use Solder Wick to remove the solder.
Last but not least you can apply so much solder to all pins that they all become connected and then heat up the blobs entirely. But you may damage the IC this way too.
There are also special desoldering tips and more sophisticated tools, but usually we don't have them at hand.
 

Thread Starter

hazim

Joined Jan 3, 2008
419
Looks like a driver to me.

Please take a better picture of the IC and adjacent components on TOP and BOTTOM layer.

What are the other two small ICs? (8-pin DIP)

Is there anything connected from the white connector directly to the broken IC?

The power supply is probably connected to some bypass caps near the IC.

GND is the gate pulse reference, at least on the output part, so there is at least two traces going directly from IC output to the MOSFET gate drive transistors, according to your diagram the KSP44/2907.
Thinking again, there should actually be three traces connected directly between IC and these transistors, +, GND and gate pulse...
Tomorrow I'll take with me a digital camera to take better pictures. The white connector is for a voltage regulator 7812 or 7805, it's connected to another circuit, giving Vcc for some parts...
You can see in the picture where it's written HT-1000A1 a third trace, it's + or GND, I'll check tomorrow.
 

Thread Starter

hazim

Joined Jan 3, 2008
419
It seems you tried to desolder it heating up all pins and then lifting it with a screwdriver.

If you don't care about the IC, cut all the pins near the IC body and then desolder pin after pin.
If you do care about the IC, use a desoldering pump to free each pin from solder, until it moves freely in the hole, you can apply more solder beforehand.
You can also use Solder Wick to remove the solder.
Last but not least you can apply so much solder to all pins that they all become connected and then heat up the blobs entirely. But you may damage the IC this way too.
There are also special desoldering tips and more sophisticated tools, but usually we don't have them at hand.
Yes that what I did exactly. I wanted to take it out and trying to know and check it outside so I care a little. I always use a desoldering pump but it doesn't do it's job with double layer. In double layer PCB I usually apply some more solder and and then heat them up and take the component out..
 

praondevou

Joined Jul 9, 2011
2,942
Brother ic is cd 4047
If it is then they didn't use it the way it's described in the datasheet. I don't see a capacitor for the oscillator between pin1 and 3. These pins seem to be connected to the other unknown IC.
Also, pin13 "oscillator output" would be connected to pin9 "external reset".... ???


This board looks almost exactly like one they produced in my other company. They burnt in regular intervals because it was a push-pull configuration where the transformers saturated (flux walking)
 
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praondevou

Joined Jul 9, 2011
2,942
could you please answer the question in blue in the picture from post 14?

Also, you will need to draw the circuit diagram around the IC.

I can't find anything like HT1000A1 on the net. what is the inverter model number?
 

Thread Starter

hazim

Joined Jan 3, 2008
419
First of all I found the inverter on the web. There is a manual and it contains a repairing guide. You can find it here: http://test.urs.com.tw/demo/powermaster/products/ap/PM-A-1000AP.htm . The model number is PM-A-1000AP and it's 24V.

Answering your question (in blue) in the picture, no they are not connected on the bottom layer.
I think HT1000A1 corresponds to the board number/version, it's not any part number on the PCB.

SgtWookie, the circuits you posted are not for SMPS based inverters, and also the surrounding circuitry of the IC is different.


BTW, I wanted to take the IC out to check it with a uC programmer I have that checks what is the IC's number if it is TTL or CMOS 40XX/45XX...

Now I think the IC is CD4011. As you can see in the picture, I tried to predict what was the number using the few remaining not erased from the part number, and also from the connections and circuit I drew for you.

I drew the surrounding circuitry of the IC and used IC 4011 in the drawing.

Other than the two outputs, there are + and ground traces connected to the oscillating circuit that drives the gates and which contain transistors KSP44 & KSP2907. I have previously posted a part of that circuit.
 

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