Panasonic PT-47WX42 Convergence Issues

[ratdude747]

Today I was gifted a Panasonic PT-47WX42 Projection TV.

It is a 1080i CRT based unit.

It was given to me with the notion that "we got it free from an estate, it doesn't work". However, I powered it on... but the convergance was really dicked up to say the least.

Step 1 of the convergance adjustment is to line up lines produced by the green CRT with marks on the TV frame:



(Engrish fail! )

However, the vertical line never makes it to the mark no matter how far I try to shift it. Also, the right side of the horizontal line never makes it to the screen edge.

It seems like the entire green tube is off balance...

Any suggestions on how to fix that? Since it is HD I'd kinda like to fix it so I can use with with a HTPC (via component inputs).

[Mr Bill]

Re: Panasonic PT-47WX42 Convergence Issues

The one and only CRT projection i have repaired was replacing the convergence chips and a couple resistors. Here is a link to a repair kit and there are a few screen shots showing some symptoms.

http://www.tvrepairkits.com/xcart/pa...epair-kit.html

[ratdude747]

Re: Panasonic PT-47WX42 Convergence Issues

Damn... Looks like my issue. Don't have $65 in that fund though so it will have to wait.

[Mr Bill]

Re: Panasonic PT-47WX42 Convergence Issues

$60 is overpriced. When I did the convergence repair in may I got the chips from ebay ($11) and the resistors were about $4 shipped from digikey.

[ratdude747]

Re: Panasonic PT-47WX42 Convergence Issues

Ah. Got it.

edit: no guides out there for free. I'm new to projection screen repair, which resistors are the ones to replace?

[ratdude747]

Re: Panasonic PT-47WX42 Convergence Issues

Pulled the main control board, are the green 2.2Ω 2W resistors the ones I need to fix? edit: like these.

Also, are the bad chips the 2 large Heatsink'd SIP chips near the Green resistors? They are labeled STK392-110. Edit- yup, they are. Should I order a pair of those?

[Mr Bill]

Re: Panasonic PT-47WX42 Convergence Issues

The STK392-110 is the chips. I'm thinking those are the same ones I got a few months ago. Check all the resistors that are in the area of the convergence chips. I only had 1 maybe 2 that were bad. When I got my chips off ebay you got 2 for $11.

[ratdude747]

Re: Panasonic PT-47WX42 Convergence Issues

Ah, I see. Will check when I get home tonight.

[ratdude747]

Re: Panasonic PT-47WX42 Convergence Issues

After testing, All of the resistors were within tolerance EXCEPT for two odd ball resistors by the +18V and -18V Convergence inputs. They were marked with 4 bands, red, violet, silver, and gold, which IIRC isn't a valid color code combo (there is no silver 3rd band). They measured in circuit to be 1.7Ω.

They look like resistors although their position, measured resistance, and code combo makes me think they are actually some sort of inductor. However, their locations are R7060 and R7066, which indicate they are indeed resistors (inductor locations start with L).

Suggestions?

EDIT- silver IS a legal band (one below black); they are 0.27Ω 5% 1W resistors. Looks like they are toast. Off to digikey...

[ratdude747]

Re: Panasonic PT-47WX42 Convergence Issues

Ordered the Chips and the resistors.

Thanks Mr. Bill for helping me out here. Most would think, as a super mod, I'd know more about this but I honestly haven't done many TV jobs, in fact, I've only done 6 LCD monitors and one LCD TV... Nothing CRT or the like (I have a few on the "fix it" list, but are bricks until I pony up for a HV probe).

[Th3_uN1Qu3]

Re: Panasonic PT-47WX42 Convergence Issues

You don't need a HV probe for 90% of CRT repair jobs.

[ratdude747]

Re: Panasonic PT-47WX42 Convergence Issues

You don't need a HV probe for 90% of CRT repair jobs.

I'd rather not slip and zap myself. And TBH, those CRTs aren't needed. two of them are likely going to get tossed (I may keep the massive 50" RCA CRT though, IIRC it has component input).

[Th3_uN1Qu3]

Re: Panasonic PT-47WX42 Convergence Issues

You won't get zapped if you follow basic safety rules and discharge all dangerous voltages before starting work on the unit.

[ben7]

Re: Panasonic PT-47WX42 Convergence Issues

You won't get zapped if you follow basic safety rules and discharge all dangerous voltages before starting work on the unit.

Hehe!

Ratdude, don't feel bad about not knowing this stuff. Thats what forums are for!

[ratdude747]

Re: Panasonic PT-47WX42 Convergence Issues

that's what the probe is for: discharging the tube. If I need one pretty bad I'll snare a used one on fleabay.

[ben7]

Re: Panasonic PT-47WX42 Convergence Issues

that's what the probe is for: discharging the tube. If I need one pretty bad I'll snare a used one on fleabay.

You can use the HV wire from some junky flyback transformer!

Also, you could just use a regular wire, with PVC pipe on each side to insulate yourself

[randtek]

Re: Panasonic PT-47WX42 Convergence Issues

All you need to discharge a CRT is a jumper lead with one end clamped around a small flatblade screwdriver shaft. Connect the other end to the ground strap stretched around the back of the CRT. while holding the plastic handle of the screwdriver, slide it under the CRT anode cap. You will hear a small crack as the CRT discharges. I have done it this way for 30 years, it is perfectly safe.

[ratdude747]

Re: Panasonic PT-47WX42 Convergence Issues

Back on-topic:

The parts came in today. I'll solder them in after class today. Here goes nothing.

[ratdude747]

Re: Panasonic PT-47WX42 Convergence Issues

No dice. Actually, if anything, its worse; the convergance controls are absolutely dead (I go to adjust it and the controls do nothing).

I replaced the two .27 ohm resistors and the two convergance chips. the other resistors seemed to be within 5% tolerance.

Any suggestions?

[ratdude747]

Re: Panasonic PT-47WX42 Convergence Issues

I hate to do this, but bump.