Hi Fellow Members,
My name is Afnan Bashir and from land down under (Australia). By profession, I ama software solution architect but I have a thing for electronics and IoT since was a kid. I have designed small IoT devices for clients as well as my hobby projects. I often used to hunt bad LCD and LED Units and fix them up and most info i got was from this forum. These days working on Yamaha RX-V677 trying to fix its PS3 issue....
afnan
Member
Last Activity: 01-20-2025, 02:58 AM
Joined: 06-16-2020
Location: QLD
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Yamaha RX-V677 Not turning on
Hi,
My RX-V677 decided to quit on me.The standby light is not there and when i turn it on it just blinks. I have checked the error codes and there is one `PS3 PRT:127 L` Looks like its a power supply issue. Checked the manual and normal values are
Normal value PS3: 132 to 168 and it monitors 5.5V
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Re: bn44-00604F No Secondary Power
I was able to find 0.33 Ohm resistor. The resistor used previously was 0.30 Ohm. Would it be alright if I use this?...Leave a comment:
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Re: bn44-00604F No Secondary Power
Thanks. Purchased....Leave a comment:
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Re: bn44-00604F No Secondary Power
Yes, shipping....Leave a comment:
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Re: bn44-00604F No Secondary Power
I am sorry if any of my comments didn't make sense. I did not factor in what will happen once the MOSFET shorts out.That schematic was for a typical SSC3S111 working. I have attached above the actual one traced from the board. You are correct....Leave a comment:
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Re: bn44-00604F No Secondary Power
Please find attached picture of the actual ST and VCC related ckt...Leave a comment:
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Re: bn44-00604F No Secondary Power
The Schematic of the board is different to those typical ckts. In the case of the board, there is no Zener. There are three 24kOhm resistors 72k total in series after B+. The voltage at ST is 130V. ST can handle up to 600Vdc. Since Vcc for the IC is isolated from B+ I wonder how shorted sense resistor can kill the IC. I am asking these questions as a student.
If Rsense shortens it will ground the IC the VRcop will be zero and the Vsc generated from FB pin will make the comparator (sec 8.2 datasheet) try even harder....Leave a comment:
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Re: bn44-00604F No Secondary Power
[URL="https://www.semicon.sanken-ele.co.jp/sk_content/ssc1s311a_ds_en.pdf"]https://www.semicon.sanken-ele.co.jp/sk_content/ssc1s311a_ds_en.pdf[/URL]Datasheet for the driverRe: bn44-00604F No Secondary Power
[URL="https://www.semicon.sanken-ele.co.jp/sk_content/ssc1s311a_ds_en.pdf"]https://www.semicon.sanken-ele.co.jp/sk_content/ssc1s311a_ds_en.pdf[/URL]Datasheet for the driverRe: bn44-00604F No Secondary Power
[URL="https://www.semicon.sanken-ele.co.jp/sk_content/ssc1s311a_ds_en.pdf"]https://www.semicon.sanken-ele.co.jp/sk_content/ssc1s311a_ds_en.pdf[/URL]DatasheetLeave a comment:
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Re: bn44-00604F No Secondary Power
I find that in this board the R sense is connected to ground side and if it gets short, worst that can happen is it gives B- to the pin, which is ground in this case. Thanks for explaining transformer ckt....Leave a comment:
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Re: bn44-00604F No Secondary Power
I will try to source sense resistor and change the MOSFET to see if it does the job. All components in that area report OK.
What I can't understand is that the transformer has 4 pins on the primary. One is connected to + from the bridge, second to MOSFET drain, third is to Bridge - and 4th to the MOSFET driver VCC.
I guess attached is a typical schematic for it. Now on ST, I have 124 v or something. Since I have good ground and ST voltage, I believe the transformer is not turning on to give feedback...Last edited by afnan; 06-16-2020, 02:57 PM.Leave a comment:
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Re: bn44-00604F No Secondary Power
VCC and GND is 0.49V DC...Leave a comment:
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Re: bn44-00604F No Secondary Power
ST - GND = 0.5 MOhm
DRV - GND = 1 kOhm
VCC - GND = 170 Ohm...Leave a comment:
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Re: bn44-00604F No Secondary Power
3s111...Leave a comment:
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Re: bn44-00604F No Secondary Power
you are correct. If this was a sense resistor then it would be required for the driver. I did not replace the driver IC. I just replaced the mosfet with same number.
So I will put a sense resistor and then try again. Anything else I should look at ? is there a way to ensure mosfet driver works?
Thanks...Leave a comment:
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Re: bn44-00604F No Secondary Power
I just removed it and put a jumper there. Yes it was 0.3 Ohm resistor.
I have investigated each diode out of the circuit and they have 0.3v forward based which is consistent with all three. What should be my next thing to focus?
I rekon when these power supplies are running I should hear buzzing sound which I don't.
The board you have referred to is correct.
I have removed JP802 and JP805 and manually given 5v to see if there is a short. The current draw is in mAs.
In your...Last edited by afnan; 06-16-2020, 06:06 AM.Leave a comment:
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bn44-00604F No Secondary Power
Initially, the FUSE was blown and on further diagnosis, I found that 9NM60N transistor was short as well. Ordered it and replaced it. Did not get any power. Then saw the power resistor right next to the MOSFET was bad and did not show any value. Bypassed it as well considering it was providing GND to the source of MOSFET. Now I get 311 v at the bridge and on the can see voltage pretty much everywhere on the hot side but no voltage at any pin on the secondary side. Nothing gets hot and I have tested diodes, caps, and resistors.
One interesting thing is that on there are three SB5150... -
Re: New Members - please post your introductions here
Hi,
My name is Afnan and I am on this forum in search of answers to troubleshoot my TV board.Leave a comment:
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