2011 Sansui HDLCD4050B 40" LCD CEK649A Power Supply Troubleshooting

[Acesales]

Hello folks, I'm working on a 2011 Sansui 40" LCD model HDLCD4050B. No LED so I figured there is no standby voltage. This is my first LCD TV repair but I have fixed lots of old vintage tube radios and some TV's. Unfortunately the PSU board has no markings at the connectors. Can anyone help me with the basics of testing this board? I'd like to start by determining whether the STBY voltage is present. Thanks!

[dskall]

Re: 2011 Sansui HDLCD4050B 40" LCD CEK649A Power Supply Troubleshooting

At least 1pin will have voltage usually around 5v from your power connector to your main board connector

[Acesales]

Re: 2011 Sansui HDLCD4050B 40" LCD CEK649A Power Supply Troubleshooting

Do I use one of the screw holes (chassis ground) as a ground for the standby voltage?

[budm]

Re: 2011 Sansui HDLCD4050B 40" LCD CEK649A Power Supply Troubleshooting

C3828 is part of standby power supply filtering circuit, so check the DCV between the two legs of that cap.

[maxvalutech]

Re: 2011 Sansui HDLCD4050B 40" LCD CEK649A Power Supply Troubleshooting

Elektrotanya.com appears to have a schematic and shows usual 5v 3.3v and 12v as outputs. Measure main cap as budm says usually above 350v. Standby 5v if ok should show red led on front of tv when switched on at pp. The outputs are measured to gnd.

[Acesales]

Re: 2011 Sansui HDLCD4050B 40" LCD CEK649A Power Supply Troubleshooting

C3828 shows 0 volts. All fuses show continuity. The line coils sound like they are making odd crackling noises. C3814 shows approx. 168V across the legs.
Thank you maxvalutech for the schematic lead. I will check it out later today after work. Yesterday the website was blocked by Google as a potential security risk.

[budm]

Re: 2011 Sansui HDLCD4050B 40" LCD CEK649A Power Supply Troubleshooting

So the standby power supply section is not running. More in-depth testing needed.

[Acesales]

Re: 2011 Sansui HDLCD4050B 40" LCD CEK649A Power Supply Troubleshooting

maxvalutech, do I have to login to find the schematic? I did some searching and did not find it. Thanks

[Acesales]

Re: 2011 Sansui HDLCD4050B 40" LCD CEK649A Power Supply Troubleshooting

I logged in to Elektrotanya and couldn't find a schematic, unfoturnately.

[budm]

Re: 2011 Sansui HDLCD4050B 40" LCD CEK649A Power Supply Troubleshooting

Hitachi/Sansui CEK649A Power Supply L40A105 HDLCD4050
http://www.shopjimmy.com/sansui-cek6...pply-unit.htm#

Pictures provided by shohjimmy.
Check fusible resistor R3825 to see if it shows around 1 Ohm or not.
Check the DCV between the two legs of the main filter cap C3814 for the standby power supply section, it should have around 160VDC.
What is the P/N as printed on top of the SMPS IC3801?

[maxvalutech]

Re: 2011 Sansui HDLCD4050B 40" LCD CEK649A Power Supply Troubleshooting

Sorry couldn't recall how I found it but now know I searched for it as DS-1107A and it came up then. Shows two connectors the second for inverter 24v output.

[Acesales]

Re: 2011 Sansui HDLCD4050B 40" LCD CEK649A Power Supply Troubleshooting

Fusible resistor R3825 is open circuit.
C3814 has approx. 168V fluctuating up and down a few volts.

[Acesales]

Re: 2011 Sansui HDLCD4050B 40" LCD CEK649A Power Supply Troubleshooting

I saw the shopjimmy ad, too. Cheap at $29 but it's more fun and rewarding to fix the old one, haha

[budm]

Re: 2011 Sansui HDLCD4050B 40" LCD CEK649A Power Supply Troubleshooting

The resistor is blown open circuit is due to shorted out SMPS IC IC3801.

[Acesales]

Re: 2011 Sansui HDLCD4050B 40" LCD CEK649A Power Supply Troubleshooting

Wow, that was quick! Thank you for the fast reply. I am sure you have seen the problem before. Can I ask what causes it to fail?
Would this be a good replacement or am I way off?

http://www.mouser.com/ProductDetail/...Fzt5f9Pg%3d%3d

[dick_barton]

Re: 2011 Sansui HDLCD4050B 40" LCD CEK649A Power Supply Troubleshooting

IC3801 (MIP2M4)

http://www.ebay.com/itm/MIP2M4-Manu-...-/121210614810

[Acesales]

Re: 2011 Sansui HDLCD4050B 40" LCD CEK649A Power Supply Troubleshooting

I saw them on ebay, too but was hoping to combine them with an order from Mouser. I couldn't find MIP2M4 in the Mouser catalog.

[budm]

Re: 2011 Sansui HDLCD4050B 40" LCD CEK649A Power Supply Troubleshooting

Check the resistance between the Source pin and the Drain pin of that IC to see what you get in Ohms.
Also check all the diodes around that IC.

[Acesales]

Re: 2011 Sansui HDLCD4050B 40" LCD CEK649A Power Supply Troubleshooting

Finally got my new SS-02 solder sucker (lost my old one) and the new parts in yesterday. The old IC measures approx. 1800 ohms between drain and source, in circuit and out of circuit. The new IC measures in the megohms.

[Acesales]

Re: 2011 Sansui HDLCD4050B 40" LCD CEK649A Power Supply Troubleshooting

I tested all the surrounding diodes and they checked out OK. I then installed the new IC and a new 2.2 ohm resistor and it worked! Thanks to everyone for helping, especially budm! Now for further testing to make sure the rest of it works.