Hello,
This is a new iteration of the same issue with the standby power being defective. Based on the past users experience and the AVR 370 schematic I was able to finally found all the bad parts and slowly going to put this back together. As a short pro-log, the initial state of the fuse (8A) led me to take a cautious approach to this.
Is never good to to replace the exact fuse and power back on, this is the worst approach.
Instead, put a small 1A fuse and use Variac to slowly increase the voltage. I did this and the 1A fuse blow quietly at very low voltage, with no bang and whistles. Then I remove the board and to see the previous damage.
I attached a picture of all the parts that have been damaged because of the 8A short. It's like the pins of the OB2358 have been all put to 260V DC, therefore the diodes and resistors got all blown up. The replacement IC will not work without the correct feedback from the optocoupler, there is a zenner there also that went bad. There is no need to put the exact zenner values, the working voltage is far less than the diode value.
Finding the chip is tricky, I fast found one in an IKEA Led lamp power supply following a thread on internet about that lamp. It's PHY368DA and as you can see, it works just fine, it's a sort of a similar/clone of the OB2358.
I also ordered OB2358 from Ali, but it will take time. I will use the IKEA lamp power board as a test jig to check the OB2358 I will receive, to check if they are real or if the working voltage is right. I will put a follow up wit more details on this thread.
I am still waiting for the small SMD resistors and diodes to come so I tested with thru hole variants, it works. Also used the rebuild transformer, since I had no idea if I will be able to get one exactly the same.
Cheers
This is a new iteration of the same issue with the standby power being defective. Based on the past users experience and the AVR 370 schematic I was able to finally found all the bad parts and slowly going to put this back together. As a short pro-log, the initial state of the fuse (8A) led me to take a cautious approach to this.
Is never good to to replace the exact fuse and power back on, this is the worst approach.
Instead, put a small 1A fuse and use Variac to slowly increase the voltage. I did this and the 1A fuse blow quietly at very low voltage, with no bang and whistles. Then I remove the board and to see the previous damage.
I attached a picture of all the parts that have been damaged because of the 8A short. It's like the pins of the OB2358 have been all put to 260V DC, therefore the diodes and resistors got all blown up. The replacement IC will not work without the correct feedback from the optocoupler, there is a zenner there also that went bad. There is no need to put the exact zenner values, the working voltage is far less than the diode value.
Finding the chip is tricky, I fast found one in an IKEA Led lamp power supply following a thread on internet about that lamp. It's PHY368DA and as you can see, it works just fine, it's a sort of a similar/clone of the OB2358.
I also ordered OB2358 from Ali, but it will take time. I will use the IKEA lamp power board as a test jig to check the OB2358 I will receive, to check if they are real or if the working voltage is right. I will put a follow up wit more details on this thread.
I am still waiting for the small SMD resistors and diodes to come so I tested with thru hole variants, it works. Also used the rebuild transformer, since I had no idea if I will be able to get one exactly the same.
Cheers
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