REPAIRING AND NOT THROWING AWAY

Richtige Fernseher haben Röhren!

Richtige Fernseher haben Röhren!

In Brief: On this site you will find pictures and technical information about Service Modes, Circuit Diagrams, Firmware Update procedure, Disassemble procedure, Universal remote control set-up codes, Troubleshooting and more....

If you go into the profession, you will obtain or have access to a variety of tech tips databases HERE IT IS Master Electronics Repair !.

These are an excellent investment where the saying: 'time-is-money' rules. However, to learn, you need to develop a general troubleshooting approach - a logical, methodical, method of narrowing down the problem. A tech tip database might suggest: 'Replace C536' for a particular symptom. This is good advice for a specific problem on one model. However, what you really want to understand is why C536 was the cause and how to pinpoint the culprit in general even if you don't have a service manual or schematic and your tech tip database doesn't have an entry for your sick TV or VCR.

While schematics are nice, you won't always have them or be able to justify the purchase for a one-of repair. Therefore, in many cases, some reverse engineering will be necessary. The time will be well spent since even if you don't see another instance of the same model in your entire lifetime, you will have learned something in the process that can be applied to other equipment problems.
As always, when you get stuck, checking out a tech-tips database may quickly identify your problem and solution.In that case, you can greatly simplify your troubleshooting or at least confirm a diagnosis before ordering parts.

Happy repairing!
Today, the West is headed for the abyss. For the ultimate fate of our disposable society is for that society itself to be disposed of. And this will happen sooner, rather than later.

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..............The bitterness of poor quality is remembered long after the sweetness of todays funny gadgets low price has faded from memory........ . . . . . .....
Don't forget the past, the end of the world is upon us! Pretty soon it will all turn to dust!

©2010, 2011, 2012, 2013, 2014 Frank Sharp - You do not have permission to copy photos and words from this blog, and any content may be never used it for auctions or commercial purposes, however feel free to post anything you see here with a courtesy link back, btw a link to the original post here , is mandatory.
All posts are presented here for informative, historical and educative purposes as applicable within fair use. NOTHING HERE IS FOR SALE !

Wednesday, 27 February 2019

NO PICTURE. SOUND OK. SONY [KV-HA & KV-HW WEGA SERIES TRINITRON TVs]

NO PICTURE. SOUND OK. SONY KVHA and KVHW WEGA SERIES TRINITRON TVs]

NO PICTURE. SOUND OK. SONY [KV-HA & KV-HW VEGA SERIES TRINITRON TVs]

Check the voltages at pins 1, 2 & 3 of (CN 703), at video amplifier card [picture tube base card].  If found abnormal, or less than 0.5VDC or so, the chroma IC on the A board should be suspected.  But before making it sure, just check the voltages at the video output pins [Pin 19, 20 & 21] of IC TDA 8844/N2.  It should be around 3VDC or so.  If there is no voltage at all, check the 9VDC bus from the SMPS power supply. This voltage comes out from a controlled regulator.  Check the voltage at the cathode of D314.  Must be 9VDC.  If not, check the voltage at its anode.  If there is no voltage at the anode of this diode, make sure that the controlled regulator is not working.  May be damaged or 9V regulator IC has damaged or not switching ON by the system control. If there is 9VDC at the cathode of D314, then check the voltage at pin number 37 of TDA 8844/N2.  If there is no voltage, check L312 for open circuit.  If these voltages are OK and still there is no voltage at the video output pins of the chroma IC TDA8844/N2, check the voltage at Pin number 7 & 8 [Serial Clock and Serial data respectively]. They should measure about 4.6VDC.  These voltages are comes to chroma IC from system control IC If there is no voltage at these pins, leave the chroma section, and come towards main system control section [IC CXP85***].
If serial data and serial clock voltages are OK, and there is 9VDC at pins 37&12 of TDA 8844/N2, and still there is no voltages at the video output pins stated above, touch the top of the main chroma IC TDA8844/N2, and feel the heat generated by it.  It can be moderately heated, but not overheated.  If it overheats, while all the above said voltages are ok, there is no further checking needed.  The IC is defective, and should be replaced