Entertainment Center: TVs, Stereos, VCRs and DVDs - KV-13M10 doesn't lit

Sony KV-13M10. The screen doesn't lit. Absolutely black. There is a sound though. I can here a high pitch noise, which makes me think that a fly-back xformer is working. I didn't measure the voltage of fly-back as my voltmeter goes up to 1Kv only. CRT's filaments are on. I make tube amplifiers, but never learned a theory behind television. Don't know where to start tracing
this problem down from. Especially without circuit diagram.

Look to the HOT (Horizonal Output Transistor) being shorted.

Best place to learn about your television set is this site:
http://an.hitchcock.org/repairfaq/REPAIR/F_tvfaq.html

Smokey ;)

Originally posted by Smokey
Look to the HOT (Horizonal Output Transistor) being shorted.

Best place to learn about your television set is this site:
http://an.hitchcock.org/repairfaq/REPAIR/F_tvfaq.html

Smokey ;)

Thanks for reply and a link to a great resource.
So is it a safe assumption that fly-back is fine if it makes that ~15kHz noise or I still need to suspect it as well?

Jenya

>Look to the HOT (Horizonal Output Transistor) being shorted.

I pulled out HOT and tested it with Ohmmeter. The only conductivity I get is between Base and Emitter. It is about 53 Ohms and in both directions. Clearly, it is not how a normal transistor would test, but I am not sure about this ones since according to that TV repair site it may have a diod inside. In the section about testing HOT it says that it should be ~50Ohm between Base and Emitter, but doesn't say if it can be
two-directonal. Also I couldn't find on the Internet any information about the transistor.
It reads
D1877
S 4B3
on it. Is there a replacement for it?
Sony didn't put a heatsink on it. Would it be a good idea to put one or it doesn't matter?

Jenya

Good Morning, jenya:

You might try calling the 800 number at our friends at Union Electronics for a general replacement transistor. You can find them at http://www.unionel.com

If you have to go to Sony, check their listings at the Parts and Service Directory at http://www.fargo-ent.com/p_s_dir/s.htm

Check the transistor as a 2SD1877. Shouldn't need a heat sink in this application. Price of a replacement is about $3.00.

Smokey ;)

I replaced HOT and fly-back. No difference. The screen is black.
There is a very strong electrostatic field in the front of the screen that lifts hair on my arm from 5'' distance. I can hear 15kHz noise. Seems like there is no video signal. What would be my next step.

I don't have a remote control for this set and was wondering if brightness is all the way down. However, I think I still would see volume scroller and channel numbers which I can change from the dash.

Jenya

jenya, Sounds like the horizontal circuit is up and running and you have high voltage at the second anode. For test purposes only, advance the screen control on the flyback and see if you have raster with retrace lines. If you do, turn it down till it just disappears. If you don't, turn it back to where it was before. If you have the schematic on this television go to the crt schematic and locate the red, blue, and green out transistors. Take your voltmeter and check the voltage reads on the collector and base of these transistors. If collector voltage is low, remove the crt module from the picture tube and recheck the read. If it's still low check your source voltage coming from the flyblack and associated resistors and electrolytic capacitors for that circuit. If the voltages reads are ok, check for cracked or burnt solder joints at kine socket on the crt board.



Post back and lets us know what you found.


Fred:)

And if you desire a remote control for the set, they are available.
One such site is http://www.replacementremotes.com/index.htm

Your remote control is the RM-861 and sells for $28.95

And, FreddyG must have come from the same era as I did. The term "kine" is short Kinescope. This is, in reality, the picture tube.
This term went "dead" about 1964 with the big color boom. But, the "old techs" still use the term (such as me). LOL!


Smokey ;)

>For test purposes only, advance the screen control on the
I don't know where that control is. What kind of colclusion we will be able to draw from this test?

<If you have the schematic on this television go to the crt
I don't have a schematic. Where can I get the one?
I hope it doesn't cost too much. I started this whole thing as an argument with my wife that I better fix the old broken one while she was almost to purchase a brand new $90 13'' TV at Best Buy. I already invested $20 into HOT and fly-back. I don't really care about $90, but the sight of that dead TV depresses me.

>check for cracked or burnt solder joints at kine socket on the crt
I checked and rechecked the crt board. I can't see any cold joints. I poked with a stick around while TV was ON and it didn't show any sign of life. The sound is fine though. There is one very weird place on the CRT board. There was a black plastic box surrounding a white 110MOhm potentiometer which is labeled H.Stat from both sides of the PCB. When I took the box off, I noticed that under one side of the box tthere is a significant amount of corroded/burned PCB. However, none of the paths were severed. I made sure with Ohmmetter that all enpoints are showing 0 Ohm connectivity. It is not clear to me why there is a need for that box in the first place and why it would corrode a PCB underneath. I am supplying a link to pictures that illustrate what I am describing.

http://home.jps.net/~jenya/Sony%20TV%20Repair/

I appreaciate your help guys.

Jenya

jenya, Looks like two of those copper traces on the soldered side of the crt board are separated due to arcing for the H-STAT control. One of those traces ties directly to the focus and screen controls then ties to that first pin on that plug connector coming from the main chassis which should be your source voltages. If the H-STAT is burnt due to arcing replace it, the part number is on the casing. The H-STAT is a convergence adjustment for the picture. If and when you get a picture you'll see what I'm talking about when you rotate that control along with the focus and screen controls to adjust the picture. The reason I said advance the screen control was to see if you had any screen brightness.
Sparky gave you the imformation needed to order Sony parts.


Fred:)

Well, Smokey is here to explain what this is all about:
(FreddyG: pay attention!)

Good evening, jenya:

Well, let's address each issue. For one, I am hanging my head in shame for the posts on this issue. We seemed to have forgotten that other folks are not "technicians" and need more explations. Well, Smokey, will comply.

First Question: If you have the schematic on this television go to the crt .
Smokey answers: You can find Service Manuals at several sites on the Internet. My favorites (with secure ordering) are at
http://www.treasurechestcorp.com/Default.htm

Then the question came up that said >For test purposes only, advance the screen control on the
I don't know where that control is. What kind of conclusion we will be able to draw from this test?


Okay, here is the explanation:
First, I will call the picture tube a "Kine" (Kinny). That's short for Kinescope and that equates to a picture tube.

When a technician encounters a set like yours with a known high
voltage (ie: the familiar crackle when the set is energized), we suspect video problems. But, we have other avenues to check:
FreddyG said to advance the screen controls (G2) on your TV to make an image on the face of the tube.
Okay. Smokey will explain this.
On all TV's (that I know of), there are screwdriver controls in and around the picture tube adjust the picture tube Screen voltages (G2) . Each picture tube has an individual electron gun that is set to project either red, blue, or green on the face of the kine. They are color coded on most sets with a red, green, blue color to identify them. So, you have a "no video" situation. The first thing a good tech. such as FreddyG, would check is (1) is the picture tube working, are the color drivers working?, and (3) and what path to follow.

The reason for advancing the G2 (Screen) Controls:
In a "no video" situation when the technician knows there is high voltage on the picture tube, he needs to eliminate certain factors.
If you advance the G2 adjustment, the electron gun for that ajustment (be it red, green, or blue) will force the kine to produce a blank screen on the face of the picture tube of the color we have adjusted. There are G2 (Screen) adjustments for each of the color guns in the projection tube (kine). So, an adjustment will make a red screen (no video), a blue screen (no video), or a green screen (no video).

Now, FreddyG, said to "back off on those controls until you had a black screen. Smokey says: This is Gray Scale adjustments.
In order for the set to display a good "black and white", the levels of the G2 adjustments must be made. Adjusting each G2 oltage so that the screen is "just achieved black", you advance the voltage using the control until the screen is showing either a red, blue, or green screen (again, no video). You reduce each control until its presentation disappears from the face of the picture tube.
In "gray scale" situations, you have established a level on the kine so that the color controls (G2) are set so that the tube will procuce black and white.

I'm going to leave now. This site is doing strange things to my editing capabilities. If you have further questions, come back and we will give you help (within the boundaries of the website).

Smokey ;)




l

Your so right Smokey, I defintely need to bring it down several knotchs. The majority of the posters I answer question for are either electronic technicians, electrical apprentices or electricians.




Fred:)

Good morning, Fred:
Understood. But, the site is open to all levels of technical expertise so we often have to get into lengthy explanations.
Your posts are excellent, however, and as a technician (actually an Electrical Engineer), I can see where you are headed with your advice. Keep up the good work.

Smokey ;)