Sony Home Theater Push Power Protect Error Solved
Sony home theater receiver model HBD-DZ810 came in with “push power protects” error now repaired.
This customer was referred to me by another customer whom I had repaired his Sony Bravia television which had backlight problem. After the phone call I visited the client and was shown the home theater receiver, testing was done in the presence of the customer to confirm what he said was the symptoms as my usual practice.
So I applied the power and the machine came up beautifully and then displayed “push power protects” on the screen and with that I confirmed the customer complaints. I took the machine with me to my workshop, opened it and did visual scanning and nothing seemed suspect.
I tested the power supply and found it was okay and all the output were within the expected range.
Next I removed the motherboard from the system and scanned the bottom side and again nothing seemed suspect.
So I decided to start testing the diodes above and I bumped on one which had reading both ways and from my electronics class was told a diode is a one-way valve and should not have reading both ways(resistance)
To be sure I lifted one pin from the circuit and re-tested again and still got the same reading (both ways). Since this diode was at the output of the amplifier circuit I was very sure this was the cause of the problem. The diode of labelled D3101, to be sure the exact diode type I had to google this model and I got the service manual from the internet effortlessly.
From the circuit diagram I was able to see the diode was actually a 39 volts Zener diode, having no smd 39 volts Zener diode I bought an ordinary 39 Zener diode and replaced it.
I re-assembled the machine quickly and very happy for the quick fix and applied the power again and with my eyes fixed on the display, after booting there again I got the “push power protects” error.
Actually it was like nothing was changed, I again removed the motherboard and decided to do more investigation on the motherboard and first I checked the replaced the diode and found has reading both sides, I soldered it out and after testing out of the circuit I noted it was okay.
This lead me to suspect that maybe the reading I am getting both ways when the diode is in circuit could point to an internal short on the digital power I.C (IC3100) which in my case was CXD9981TN.
To be sure if the I.C.3100 was causing the problem I removed it out of the circuit and replaced the zener diode. I re-assembled again and applied the power but this time without much expectation and after booting up this is what I saw.
The machine no longer goes into protection mode, I connected the speaker for testing purposes and I love what I heard. Nice, soft and soothing music coming out of the machine. Since this I.C was not in my market, I ordered it online from China and because of the outbreak of Covid-19 there was a lot of delay in shipping the part to Kenya.
I explained this to the customer and requested him if he can be using the machine without one amplifier and he agreed. I took the machine back and paid me ¾ of the total charges, we agreed that when the market is back to normal will replace the faulty I.C.
After testing the machine, the client was happy and I left it at that, now it is over one month and customer has not called with any complaint and therefore I hope he is still enjoying.
You can learn more about home theater repair by reading my DVD player repair guide sold here.
Thank you friends. Take care and maintain social distance.
Humphrey Kimathi is from Nairobi Kenya and the author of:
3) CRT Television repair course and
4) Basic Electronics course.
He is also a blogger at Electronicsrepairmadeasy.com
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