Vistron vis042 plasma on standby

[rove25]

Hi I have a Vistron vis042 plasma that is stuck in standby,
I have replaced the power board as this seems to go on most tv's but still the same,
symtoms are plug into mains, switch on tv, 2 clicks are heard within 2 seconds then a 3rd click 2-3 seconds after, then red standby lights up, have checked for blown/bulging caps non found, I am a newbe to tv electronics, any help would be appreciated.

Pete.

[PlainBill]

Re: Vistron vis042 plasma on standby

Hi I have a Vistron vis042 plasma that is stuck in standby,
I have replaced the power board as this seems to go on most tv's but still the same,
symtoms are plug into mains, switch on tv, 2 clicks are heard within 2 seconds then a 3rd click 2-3 seconds after, then red standby lights up, have checked for blown/bulging caps non found, I am a newbe to tv electronics, any help would be appreciated.

Pete.

One very popular series of books in the USA are the tales of Harry Potter and his friends. His wizardly methods don't work for us, we're Muggles.

Follow the links in my signature for taking and attaching pictures. I want one covering the full back of the TV (with the back cover off, obviously). I also want pictures of every label on the back of the plasma panel that specifies voltage, or model number of the panel. And on the right side (as viewed from the back) there should be the Y sustain card. This will probably be 12cm x 25cm. A sharp, clear picture of that showing all part number labels would be a big help.

PlainBill

[rove25]

Re: Vistron vis042 plasma on standby

Hi Plainbill
Find attached photo's hope these are ok, if not let me know and ill take a photo again,
Many thanks for the fast reply,

Pete.

[PlainBill]

Re: Vistron vis042 plasma on standby

Excellent quality pictures. I wish we got more like those.

A quick background. LG Electronics manufacturers plasma display panels and sells them as an assembly to TV manufacturers, including Vistron. The assembly usually consists of the plasma panel itself, the Sustain cards (Y on the left, Z/X on the right), the buffers (Y on the left, X on the bottom), the main control card (hidden behind the 'TV board' towards the bottom) and the power supply. Vistron (or one of the other dozen plus manufacturers who buy panel assemblies) then add the 'TV board', audio amplifier, speakers, etc. The 'TV board' contains the tuner, the signal inputs, the signal processors, the over-all control processors, and additional power supplies for those components. It also does some rudimentary checking of the main power supply. If there are any failures, it goes into 'protect mode' and shuts down the main supply.

For further reading Scribd has training manuals for several models of plasma TVs. I'm not sure if they deal with the exact panel you have, but at least read them for discussion on disconnecting the various sustain cards and buffers. The connectors are fragile. The first is 13287511-Lg-Plasma-Tv-Full-Training-Manual, the second is 7580885-LG-Plasma-TV-Full-Training-Manual. Again, Google them.

There are three possible reasons for the symptoms you describe. One is that the power supply fails to produce the voltages required. A second is that the 'TV board' fails to produce some of the voltages IT requires. The third is that one of the two sustain boards or the X buffer overloads the power supply.

You have eliminated a defective power supply as the likely cause. The next likely culprit are the sustain boards or the buffers.

First, a warning. The power supply produces voltage of up to 350 VDC. This is enough to seriously readjust your outlook on life. Be very careful.

Step 1. Disconnect the TV from the mains supply.
Step 2. Wait 5 minutes for the power supply to discharge. Parts of it are live when ever the TV is connected to the mains supply.
Step 3. Disconnect the red and blue cable running from the power supply to the Z-Sustain (this can be done at either end).
Step 4. Connect the TV to the mains supply.
Step 5. Turn on the TV.
If the TV repeats the same pattern, the problem is not with the Z-Sustain. If the TV stays on, and you have sound (but no picture) the Z-Sustain was bad. Replace it.
Step 6. Disconnect the TV from the mains supply.
Step 7. Wait 5 minutes.
Step 8. Reconnect the red and blue cable.
Step 9. Disconnect the gray cables running from the power supply to the Y-Sustain.
Step 10. Connect the TV to the mains supply.
Step 11. Turn on the TV.
If the TV still repeats the same pattern, you have a dilemma. Some of LG's designs check for the presence of the Y-Sustain. If it is not connected, it goes into protect mode. The only way to effectively test is to replace the Y-Sustain and the Y buffers with known good ones. Other designs do not do that test. In that case, the problem is with the 'TV board'.

I say that you have a dilemma because adjustment of the Y-Sustain requires use of an oscilloscope. Given the cost of the Y-Sustain and buffers, it's probably not practical to repair the TV.

PlainBill

[PowerAmpFreak]

Re: Vistron vis042 plasma on standby

Check fuses on drive boards. And use your nose to smell.
I bet the fuse on Y-SUS board is blown. This means the IPM (hybrid circuit under the big heatsink) is blown.

[rove25]

Re: Vistron vis042 plasma on standby

Hi Plainbill followed your easy to follow steps, sound came on tv went off stanby, then test in reverse, oh yes i had allready check fuses. awaiting a Z-Sustain board, will inform you when fitted and tested,
Pete.

[rove25]

Re: Vistron vis042 plasma on standby

Hi Plainbill, your the man, followed your instructions, fitted a z sustain board and well all works, many thanks,

Pete.
next project?.

[PlainBill]

Re: Vistron vis042 plasma on standby

Hi Plainbill, your the man, followed your instructions, fitted a z sustain board and well all works, many thanks,

Pete.
next project?.

Congratulations.

I'll give you a choice for your next project.

1. An oscilloscope is a very useful tool for troubleshooting TVs and monitors. I want you to find a supplier of a battery operated dual channel oscilloscope with a minimum of a 5" display (color would be nice, but is optional) and 200 Mhz bandwidth. Frequency counter, DMM, capacitance and ESR functions would be a plus. Oh - and it must sell for under $100.

2. Get mpobanion to give us some decent pictures of the power supply in his Hitachi 42HDF39.

PlainBill