Sony KDL-55EX640 (630) DEAD SET

[t4796]

Hi,

I've have this machine no standby light. I've taken out the boards and found somebody has had a go at the power supply already.

I have been unable to locate a schematic at this point. I believe sony refer to the power supply as GE55. It is DELTA branded and says DPS-195AP-1 on the board.

Here is the nightmare... someone has removed one, possibly two zener diodes, and I have no schematic to work what value they should be.

So far I have found a delta power supply training manual and it has very similar circuits so I have hoping somebody could help me work out what a suitable value could be?

[newtothis]

Re: Sony KDL-55EX640 (630) DEAD SET

Picture of boards, highlight worked areas

[t4796]

Re: Sony KDL-55EX640 (630) DEAD SET

Thanks for the reply NTT, here we go

The main damage is shown in the third photo next to J20 with some traces damaged and diode(s) missing.
The bridge rectifier BD1 has been soldered, as have the heatsink attachment points, Q701A, Q701B, Q601, Q800. R794 near Q701B looks a bit mulched from the solder attempt also.

[newtothis]

Re: Sony KDL-55EX640 (630) DEAD SET

Can you see the markings on ZD904?

Should be the same rating for the missing Zeners

[t4796]

Re: Sony KDL-55EX640 (630) DEAD SET

I'll desolder ZD904 and have a look.
This is IC902: IN1M101 "Precision AC Brown-out Supervisor IC"

[t4796]

Re: Sony KDL-55EX640 (630) DEAD SET

My eyes aren't what they used to be, but it looks like it says NZ|3B.

[budm]

Re: Sony KDL-55EX640 (630) DEAD SET

Look at your pictures, as you can see the designators as printed on the board are ZD900, ZD901, ZD906 are connected in PARALLEL, and unless you match all three Zener diodes precisely, they will never work properly. I doubt that it is missing, the board may be stuffed with different parts for particular printed circuit board assembly (PCBA), so I doubt that there will be more then one Zener installed in that location.
No standby lights problem, you should start looking to see if there are standby Voltage feeding the main board first.

[t4796]

Re: Sony KDL-55EX640 (630) DEAD SET

Thanks for the reply budm. I agree there is probably only one zener missing. It would have been removed and the pad damaged. One of the intact pads looks at though it never had a component installed, just clean solder with no bump.

So one zener is missing. I was reluctant to do any more tests until I could work out what value that zener was.

[budm]

Re: Sony KDL-55EX640 (630) DEAD SET

How many diodes are in place, I only see 1.

[t4796]

Re: Sony KDL-55EX640 (630) DEAD SET

.

[t4796]

Re: Sony KDL-55EX640 (630) DEAD SET

Sorry budm, it is probably hard to see in the photos, because there is a metal plate in the way from the top view. There are no diodes present in any of the (ZD900, 901, 906) locations, the only thing soldered in place is the link J20 which runs off to pin 6 of IC902.

The missing zener trace runs off to parallel with two capacitors the 'delay time setting capacitor' pin5 at IC902 and the 'Comparitor passive terminal input1' pin 6 at IC902.

[budm]

Re: Sony KDL-55EX640 (630) DEAD SET

OK, I look at shopjimmy and see that the heatsink is in the way to see anything.

[t4796]

Re: Sony KDL-55EX640 (630) DEAD SET

If the absolute maximum is 7v for those two pins, could I put a 7V zener?

Please excuse my scribble

[budm]

Re: Sony KDL-55EX640 (630) DEAD SET

I see that the Zener is connected to the AC Voltage divider R1A, R1B, R2A, R2B to detect the AC, the Anode is connected to one end of the cap C915, the other end is connected to pin5 of the IC. C916 one end is also connected to the Anode of the zener, and another end of C916 is connected to pin 6.
You can also see that the trace connected to the Anode is also goes all the way to the OPTO to communicate with the main board to tell if the AC Voltage level is OK or not.
If it is Brown out detector that means the Zener will not be conducting and when the brown occur (AC Voltage is too low to safely operate the TV). But the way it is used, it will rectify the AC in the Negative cycle and will not conduct in positive cycle unless the Voltage is above the Zener Voltage.

[t4796]

Re: Sony KDL-55EX640 (630) DEAD SET

I hadn't followed the trace up to the opto. It's gonna take me a minute to digest what you just wrote
So are you saying it isn't there to protect the inputs? I thought the IC was to manage brown outs. I'll have to study some more.

[budm]

Re: Sony KDL-55EX640 (630) DEAD SET

This detection circuit will not stop the standby power supply from working, so do you have standby Voltages at all?

[t4796]

Re: Sony KDL-55EX640 (630) DEAD SET

I will measure now. I just saw the damaged traces and got fixated on that

[budm]

Re: Sony KDL-55EX640 (630) DEAD SET

Can you please check to see if the resistance between pin 2 (VSS) and the Negative leg of the main filter cap is >1 Ohm? Make sure the AC is not applied and the cap is discharged.
Worst comes to worst the Brown out detection can be bypass for now to see if the TV will function, it is for brown out protection only so for testing purpose we do not need it to function. So far the trace seems to be connected to pin 1 of the Opto which is the LED for sending side.

[t4796]

Re: Sony KDL-55EX640 (630) DEAD SET

ok 344V at main cap, 0v at standby pin. sorry, just refreshed and saw your reply. will test now.

[budm]

Re: Sony KDL-55EX640 (630) DEAD SET

http://assets.shopjimmy.com/media/ca...M/IMG_1131.JPG

Picture provided by SJ.

Pin1 of the CN2 is the 3.3VSB standby Voltage to run the main board. So you are not getting the 3.3VSB?