Question about JVC AV-56WP74 56" Rear Projection HDTV-Ready Television

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Possible short or maybe thermal breaker?

I already went through the convergence problem with this tv about 6 months ago. now when you turn it on it sounds liie its comin on but seems to blow a thermal breaker and starts power cycling. Is this easy to trouble shoot. Im not afraid to try after doing the convergence board.

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1024x768 Normal 0 Won’t start

The power supply has an automatic shutdown circuit that senses a shorted component and excessive current flow.

If you can access the convergence board and remove the plugs one at a time (red, blue or green) for the convergence output, the TV may start up and show a picture with the unplugged color misaligned.

This confirms a short in the convergence output. The convergence IC failure can show up as coloured outlines or power supply shutdown.

If this does not help, then there is some other short circuit in power or deflection circuits. You need a technician to troubleshoot HV or power problems.

Replacing the output amplifiers (located within the Convergence IC's) allows the pictures to line up correctly, and no more color outlines or power shutdown.

This is the most common fault in all makes of rear projection TVs.

Some models of TV require major disassembly and considerable shop/manufacturer's support to repair because of their design that causes other power supply or vertical deflection problems. The poorly designed products require a "bench" repair that can typically cost from $350 t0 $700.

Some TVs are designed for on-site repair and have more reliable circuit design that does not usually cause damage to other parts of the TV when convergence chips fail. The ones that usually allow reliable on-site repair are JVC, Samsung and Hitachi.

It is normal to have some resistors in the circuit burn up or increase in value from the heat (from 2.2 ohms to 5 or 10 ohms). These resistors must be replaced with the right value or the chip may fail again.

This is not a simple repair like changing batteries or a fuse. Reading through the other posts shows many that try and end up with bigger problems.

Your JVC uses STK 392-110 IC's. Misinformed people replace the IC's with other "new and improved" IC's, like STK 392-150. These are devices with different characteristics and require different value resistors in the circuit. Replacing with the STK 392-150 will cause overheating of the resistors and a damaged IC.

If you are in Calgary, I can help. If not, get someone that has experience working on your JVC. My website is below with some costs and explanation.

calgaryconvergencerepair.weebly.com/convergence-explanation.html

Good Luck,

Easyab

Posted on Jul 07, 2008

  • 1 more comment 
  • Lithium600mg Sep 01, 2011

    Can you provide the upgraded resistor values for the STK-392-150 IC's for the AV-48WP74?

  • Lithium600mg Sep 01, 2011

    Can you provide the upgraded resistor values for the STK-392-150 IC's for the AV-48WP74? My email is Lithium_600mg@yahoo.com. Thank you.

  • easy alberta
    easy alberta Sep 01, 2011

    The information regarding upgrading ICs is from people that do not have hands-on experience with Convergence repair. Changing ICs to 150 from 110 requires re-design of the circuit. Use the 110 ICs (or 120 IC). The blogs are full of request for help after the "upgrade???" to 150 or other ICs.

    People that suggest changing the ICs to 150 (upgrading???) sell the ICs or parrot what they have heard from others. JVC have very clever design people. 110 ICs work fine, 150 ICs are different and have different current flow that causes the resistors to burn up. The increased current flow can also cause the Power Supply safety circuit to shut the TV down because excessive current flow is detected. 2nd problem is that most internet sourced ICs are poor quality and usually do not work.

    We do not change the values of the resistors, just use the original/correct 110 or 120 IC.

    Robert

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the video color distortion with the bowing in the center is called a convergence failure. the 6 blinks indicate a power supply shutdown for high voltage protect. the 14 blinks is just the tv trying to turn back on. you may be having to problems with the convergence and the 6 blinks or it may be related because the convergence amps can cause shutdown if they are shorted. i suggest calling a serviceman per the possible tow different failures. good luck

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Your TV most likely a convergence failure. ( common problem )

Here are some of the most common symptoms and example photos of a convergence problem


  • Screen looks 3D
  • Colors don't line up
  • One or more colors can't be adjusted when using the convergence menu.
  • Screen is bowed or warped.
  • TV shuts down
  • TV Chirps
Here are some photos of convergence problems.

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Here is a quick test....

Using your original remote go-to the tv settings then goto the convergence section.

Try to adjust the red and then the blue convergence.

You should be able to move them up, down, left, and right.

If you can't move them in all directions your convergence chips are bad and should be replaced. This is a common problem.

0667c5f.pngSOLUTION

You will need to replace the convergence chips and possibly some convergence resistors and pico fuses. Its a fairly easy DIY job or you can call in a pro. If you want to do the repair yourself check the site www.TvRepairKits.com. Their kits include a photo instruction guide, original OEM Sanyo STK chips, convergence resistors, pico fuses, thermal paste, email/phone support, etc.

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Don't feel bad about Mits. All the projection companies and all the new TVs have markedly poorer reliability than the good old CRT types. You should see all the class action lawsuits against even some of the best companies!

The power supply section is not working.
Common possibilities are:
- Convergences amps have failed overloading the supply
- High-voltage section (flyback transformer) has failed
(happens sooner or later, about 8 years typical))
- CRT tube has failed overloading the supply
- Power surge has popped the power input circuit.
(Fuse, rectifier diodes, turn-on relay etc)
- One of a hundred of electrolytic capacitors has failed short overloading the supply. They dry out with age, are cheap to replace, but hard to find which one it is.
- Or any of many other possibilities.

In short, you need a experianced tech to troubleshoot this.

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