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Old 10-28-2020, 01:19 AM   #46
beetle1303
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Join Date: Jul 2019
City & State: Singapore
My Country: Singapore
Line Voltage: 230VAC 60Hz
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Default Re: Tefal GV8962 Pro Express steam iron - no power

Quote:
Originally Posted by budm View Post
At this point you can leave the 100 Ohms resistor for testing for now.
So the 24V buck converter is working now, now we need to trace out the other power supply section for low Voltage that is used for running those IC's (U3, U4) next.
So look up the part number of some of those IC's so you can look up the spec sheet to locate the VCC pin of the IC then you can find out if the VCC is present or not for the IC's to run.
Check Voltage of U2, it looks to be LDO Regulator IC.
I also see some bad solder joints, one looks burnt, others you can see ring developing around the joint, so look for ring around the solder joints and resolder them.
BTW, that small white connector, what is connected to that connector?
The black color that looks burnt is permanent black marker ink, on the the joints that have wired soldered directly onto. The ring around the solder joints - except for the huge wire joints with black marks, practically all the joints has some sort of indentation. Some looks like a ring, most are just dings. I re-soldered most of them.

I looked up for and these are the 2 ICs:
1) Top, bigger one: PIC16F1933: pin 19 & 20 measure 0.03Vdc
2) Bottom, smaller one: HC595A: pin 8 & 16 measure 0.03Vdc

Pressing power button on/off has no effect on the readings.
Attached Images
File Type: jpg ICs.jpg (2.79 MB, 5 views)
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