5TUZ52C horizontal deflection output ..

[Kiriakos-GR]

My SONY 19" CRT stopped working today , after of 10 years of excellent service. (CPD-G420)

With out it, I feel like blind , and currently I use an smaller Hitachi CRT.

I took it apart , and trying to find what failed ,
at my first step to this process  , I am checking the 5TUZ52C ,
with my dmm's  , and every one gives different numbers in Kohm ,  
and the measurement  depends in what range I do the measurement !!
The only positive are that it measures only by the one way , and so its not sorted ,
but how I can tell if its healthy ?  

Any ideas are more than welcome ..

( Currently the status of the CRT are ,  Power on - degauss - green LED turn to yellow and goes on-off-on every second , no high voltage )

http://www.datasheetcatalog.org/datasheet/toshiba/3525.pdf

[djsb]

Are you testing more than 1 device? Have you tested it with the multimeters diode tester (if it has one)?

[Kiriakos-GR]

Yes at the diode tester range i got more accurate numbers , from all the multimeter s,
and so it measures 440ohm ..

(thanks for the tip , my mind had stuck on measuring it, with the resistors mode.)

Because this CRT are actually my , and I am in stress , I do not think clearly right now..  

[zaoka]

5TUZ52C is damper diode, should check like regular diode, select diode test on multimeter before testing. Do not test with ohm meter. These never go bad btw.
The best way to test it is with analog ohmmeter, select 1K range and see. One way meter deflect, the other way it does not.

Make sure Q505 (mosfet) and Q508 are ok.

What is the symptom? Do you get any voltage on pin 2 of L510?


You can get service manual here: http://www.givemefile.net/smanuals/monitors/sony/file/39580.html

[Psi]

First thing i would do is download the service manual if you dont already have it.
It may even have a troubleshooting section that describes this exact symptom and what causes it.

Be a good idea to check out all the electrolytic capacitors on the boards and unsolder+test any that look a little dodgy and/or any that are next to heatsinks.  A bad capacitor may not be the cause of the problem but it may have caused something else to fail.

Next i would have a look at the circuit diagram and start isolating sections to see if the problem stops.  eg, unsolder or break the power to the flyback to cut off the HV supply. Then power it up and see if it still does its on-off-on problem. The HV section on CRTs is quite prone to failing/shorting, so removing it from the system will prove if thats the problem. They normally power up fine without it, you just don't get a picture.

The on-off-on problem could easy be the power supply section detecting a short somewhere and resetting.

The normal warnings apply for testing CRTs though, don't let charged capacitors, the tube or the HV section kill you

[Kiriakos-GR]

I have download the repair manual , I have even print the assembly section and the part list.

The problem about testing this monitor , is that its almost impossible to have the PCB in place with out the metal cage in place too.

I have now just the PCB at hand , and I am looking to verify the condition of major parts.
Its very hard to unsolder the parts , SONY had add at its PCB hole metallic inserts,
and the parts pass threw them ..

Even so I am very puzzled because I own this monitor sense 2001 , and the screen its not that sharp any more.
I will try tomorrow with " clean head " to see the status of the other major transistors ,
in case that the Fly-back got burned , I will just trash it.   

zaoka thanks for the tips ..