OCTAGON SF-4008 100% Solution of self-closing problem . The first solution Sharing on the Internet is here in detail.

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OCTAGON SF-4008 100% Solution of self-closing problem . The first solution Sharing on the Internet is here in detail.


Post by sakisvele »

OCTAGON SF-4008 100% Solution of self-closing problem . The first solution Sharing on the Internet is here in detail.

Dear Forum friends, my Octagon SF-4008 device, which I have been using for a long time, has recently started to turn itself off at certain intervals. (It goes into standby mode) Thinking it's from the image, I tried it in a different image. Same problem again. Sometimes after half an hour, sometimes 3 hours later, it would switch to standby by itself. When I opened it from the remote control, it would close again immediately. After restarting the device, the same problem persisted after a few hours. Thinking that the filter capacitors at the input and output might leak in the power supply adapter connected to the device, I tried it with a different DC 12V adapter with the same value. After a few hours, the device went into standby mode again. In my research on the internet, I saw the posts of users who had the same problem on the subject. But no solution has been shared on this issue. Technical services will be angry with me, but first in this forum, I am sharing the exact solution for this device. In the measurements I made on the mainboard of the device, I saw that the input filter capacitor (470uF 16V) lost 50% of its value. Friends who have the same problem with SF-4008 can plug in 470uF 25 or 35V. I used a 470uF 50 volt capacitor. If we try to explain the problem technically in detail;

It is not enough to measure the capacity of a capacitor to understand whether it is healthy when repairing a device. We should also look at the ESR value. A capacitor with a normal capacity but with a high ESR value cannot fulfill its duty and either does not work in the circuit or cannot provide the performance it should provide. LCR meters may reveal many capacitor failures.

Electrolytic capacitors often deteriorate due to operating at extremely high temperatures or drying out of the electrolyte. Since the ESR can be measured with the LCR meter, we can detect these faults. But there are some capacitor faults that cannot be detected even with the LCR meter. For example, sometimes capacitors start to leak current. You cannot detect this by measuring resistance with an LCR meter, because it only happens when there is a certain voltage. In such cases, an insulation tester is also needed. Due to drying, the plates of the capacitor have approached each other, so the capacitance value has increased. But due to the approach of the plates, the voltage strength decreased and there was a serious leakage current under 100 V. So it would be wrong if we say that we can test a capacitor 100% with an LCR meter. The only way to 100% test a capacitor is

Sometimes the capacitance values ​​may increase as the capacitors deteriorate. For example, let's say the capacitor started to dry and the electrolyte between the foils decreased. In this case, you will see the capacity value increased as the foils will come closer to each other.:)But of course, the closeness of the foils has now reduced the voltage resistance of that capacitor and maybe its insulation will collapse when it sees the voltage in the circuit. The ESR of a capacitor is considered as a series resistance to the capacitor. In fact, ESR is a resistor placed to represent losses due to different physical effects during the operation of the capacitor. In fact, the majority of the losses are not resistive. Therefore, it should not be thought that the series resistance of a capacitor with a high ESR has increased. Instead, it is necessary to think that the losses of that capacitor due to different physical effects have increased. I guess it was too technical an explanation, friends...

Considering that most people who have this problem put this beautiful device on sale, we can easily solve the self-closing problem by replacing the 470uF capacitor at the input of the SF-4008.

thnx @ ozgurece

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