REPAIRING AND NOT THROWING AWAY

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!

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All posts are presented here for informative, historical and educative purposes as applicable within fair use. NOTHING HERE IS FOR SALE !

Friday, 8 February 2019

HOW TO CHECK A COLOR PICTURE TUBE _ COLOR PICTURE TUBE FAULTS GUIDE

HOW TO CHECK A COLOR PICTURE TUBE _ COLOR PICTURE TUBE FAULTS





  • Only the heater pins should have resistance. All other pins have infinite resistance to each other and to either heater pins.
  • Used picture tubes that have a heater-cathode leakage/short have a low restoration success level.



Symptom
Suspect
Check
Procedure

Dark picture or one color missing.
Heaters Open
Apply 6Vdc to the heater terminals.
Some heaters are connected in parallel,
others in series but all
take 6Vdc.
·         Clean the CRT pins and examine the socket for corrosion.
·         Apply 6Vdc to the CRT heater pins, looking for a glow in all three heaters.
  • If a heater(s) does not glow, replace the picture tube
Dark picture
Grid 1 to Grid 2 short.
There should be infinite
Resistance between the G1 and G2 pins.
·         Unplug TV and remove C board
  • Apply 15-20Vdc between the G1 and G2 pins to vaporize the short. Current limit the power supply to 1 Amp.
Bright red, green or blue picture.
One color retrace lines
may be present.
Retrace lines are diagonal lines that run
from lower left to the upper right corner
Heater Cathode short.

OR

Cathode to Grid 1   short
·         Remove the R, G or B video input to the CRT for the bright color.
·         If that color is still bright, the tube is bad.
  • There should be infinite Resistance between any CRT pin to either Heater pin.

Bright picture with retrace lines and/or
poor focus.
Grid 2 to high voltage
Grid 3 leakage.
Symptom is that all three colors are bright
Reduce G2 / screen voltage to the lowest setting.
Vary focus control to both limits several times.
Put on safety apparel.
Place the tube face down and lightly tap the neck to dislodge the particle.
RGB Rainbow










Purity / Beam landing is off.
Aperture grill was
unseated in transit








The TV s degaussing
circuit did not
demagnetize aperture
grill metal support.
Rainbow of colors can
start at the top or bottom (bottom rainbow shown).





Same color blotches
remain at that area of the screen regardless of picture screen
changes.
A loose aperture grill is
dangerous and may cause tube implosion. Use all safety precautions.
 Do not jar set. Transport TV face down.

Do not manually Degauss the picture tube with a strong degaussing coil.
Repair the TV s degaussing circuit. The thermistor or
cold solder is usually at fault.
Posted By: FRANK at 06:11
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