Sony Bluray BD 370 power board APS-257 burnt resistors values

Thread Starter

ssmathew

Joined Jan 15, 2021
7
My Blu ray player Sony BD-370 recently blew its power supply board. The service manual of the Sony BD-370 does not include the schematics of the smps power supply board and I could not find a circuit diagram searching the web.
The power board number is APS-257 and manufacturer part number is 1-474-194-11.

On checking the board, the switching MOSFET 3N62K3 was found to be damaged. In addition, 3 resistors were also burnt (please see attached images). I am now stuck because I do not know the values of these resistors to replace it. Spent a lot of time searching the web but could not find the circuit diagram or a picture that was clear enough to show the values of these resistors.

The resistor reference numbers on the board are R106, R107 and R113. Any help finding the values of these resistors is appreciated.
 

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wayneh

Joined Sep 9, 2010
17,152
My Blu ray player Sony BD-370 recently blew its power supply board. The service manual of the Sony BD-370 does not include the schematics of the smps power supply board and I could not find a circuit diagram searching the web.
The power board number is APS-257 and manufacturer part number is 1-474-194-11.

On checking the board, the switching MOSFET 3N62K3 was found to be damaged. In addition, 3 resistors were also burnt (please see attached images). I am now stuck because I do not know the values of these resistors to replace it. Spent a lot of time searching the web but could not find the circuit diagram or a picture that was clear enough to show the values of these resistors.

The resistor reference numbers on the board are R106, R107 and R113. Any help finding the values of these resistors is appreciated.
You might consider replacing the power supply instead of fixing it. It might be hard to isolate it but if you can, a new power supply is very cheap compared to the time, efforts and parts you may dump into the old one.

Update: just looked at the picture. Should be an easy peazy replacement
 
I have a BDP-S370 and took it apart. But different PSU than yours.
Mitsumi SRV2215UC, 1-474-195-21. Primary MOSFET is P9NK50ZFP (ST), IC101 "2A10".

Your three resistors are the current-sense, all would be the same value. The SMPS IC might be damaged as well, check the gate resistor and IC output pin too.
 

Thread Starter

ssmathew

Joined Jan 15, 2021
7
You might consider replacing the power supply instead of fixing it. It might be hard to isolate it but if you can, a new power supply is very cheap compared to the time, efforts and parts you may dump into the old one.

Update: just looked at the picture. Should be an easy peazy replacement
I agree. I might just do that if I cannot find the resistor values. Shipping to where I stay is a problem both time and cost wise. Components however are more easily sourced. Hence the effort to replace components.
 

Thread Starter

ssmathew

Joined Jan 15, 2021
7
I have a BDP-S370 and took it apart. But different PSU than yours.
Mitsumi SRV2215UC, 1-474-195-21. Primary MOSFET is P9NK50ZFP (ST), IC101 "2A10".

Your three resistors are the current-sense, all would be the same value. The SMPS IC might be damaged as well, check the gate resistor and IC output pin too.
The Mitsumi's SRV2215UC board is used in regions with 110V - 125V like US/CAN. Sony's APS-257 is used in 220-240V regions. The three resistors in this board are in series with the auxiliary winding powering the switching IC. Like you said, a damaged SMPS IC could have caused the resistors and MOSFET to blow.
 

Thread Starter

ssmathew

Joined Jan 15, 2021
7
The Mitsumi's SRV2215UC board is used in regions with 110V - 125V like US/CAN. Sony's APS-257 is used in 220-240V regions. The three resistors in this board are in series with the auxiliary winding powering the switching IC. Like you said, a damaged SMPS IC could have caused the resistors and MOSFET to blow.
 

wayneh

Joined Sep 9, 2010
17,152
Shipping to where I stay is a problem both time and cost wise.
If the output is a common voltage such as 12VDC or 20VDC, you can probably find a suitable power supply easily such as a used laptop power brick (typically 19-20V and ~4-5A) or an old hard drive or modem supply (12V). Old LCD monitors are another source of power supplies, although PS failure is a common cause of death.

Do you know the power specs?
 
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Dodgydave

Joined Jun 22, 2012
9,951
The Mitsumi's SRV2215UC board is used in regions with 110V - 125V like US/CAN. Sony's APS-257 is used in 220-240V regions. The three resistors in this board are in series with the auxiliary winding powering the switching IC. Like you said, a damaged SMPS IC could have caused the resistors and MOSFET to blow.
Looks like this is a popular problem with various PSUs, here's a repair kit for them.
The 3 resistors are in parallel for current monitoring by the chip, which looks like a Viper.
https://m.aliexpress.com/item/1984411950.html?trace=wwwdetail2mobilesitedetail
 

Thread Starter

ssmathew

Joined Jan 15, 2021
7
Looks like this is a popular problem with various PSUs, here's a repair kit for them.
The 3 resistors are in parallel for current monitoring by the chip, which looks like a Viper.
https://m.aliexpress.com/item/1984411950.html?trace=wwwdetail2mobilesitedetail
This repair kit would have been ideal but looks like the listing is no longer available. The 3 resistors are between source and ground, so it is current sensing as prairiemystic and you pointed out. Attached is a picture of the switching IC. It is a 1271A.

I found a reference design for a 19V/3A adapter using the On Semi NCP1271A that is very much similar to this board. Calculating the resistor values should not be a problem.

Reference design page link:
https://www.eeweb.com/19-v-3-0-a-universal-input-ac-dc-adaptor-using-ncp1271/
Direct PDF file link:
https://www.eeweb.com/wp-content/up...iversal-input-ac-dc-adaptor-using-ncp1271.pdf
 

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Thread Starter

ssmathew

Joined Jan 15, 2021
7
If the output is a common voltage such as 12VDC or 20VDC, you can probably find a suitable power supply easily such as a used laptop power brick (typically 19-20V and ~4-5A) or an old hard drive or modem supply (12V). Old LCD monitors are another source of power supplies, although PS failure is a common cause of death.

Do you know the power specs?
The board puts out +12V +6V and -6V. The BD player consumes 22W max, so the power output by the board should also be around that.
 

Thread Starter

ssmathew

Joined Jan 15, 2021
7
Finally received the components and got the BD player to work.

Replaced the switching IC, MOSFET, a Schottky diode and 7 resistors. Based on the output power, transformer primary inductance, input voltage range and switching frequency the the peak primary current calculated was around 1.15 A. Given that the voltage where I live can at times drop to the 190s instead of 230V, the short circuit trigger current was set at 1.3 A using the current sense resistors. Other blown out resistors replaced were in the gate trigger, slope compensation and a 0.47ohm between the bulk capacitor and transformer primary. Could not source an smd schottky diode in time and had to do with a through hole by adjusting its leads.

Tested the board with a 20W load assuming that of the 22W consumed by the player at least 2W would be lost due to inefficiency. The smps went into protection with a 24W load and an output short circuit as set. The player ran for approximately 14 hours in continuous playback and 13 hours in standby condition (the switching IC enters soft skip mode in standby as per the datasheet). The FLIR camera thermal image of the board showed a maximum temperature of 51°C (124°F).

Thanks to all your replies, I am a little wiser with regard to SMPS and have a working BD player.
 

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