older sony RPTV problem

this is my first post here but hopefully someone can point me in the right direction or help out.

i just recently picked up a used sony KP53XBR200 53 inch rear projection tv. it's visibly in very good condition and i tested it on-site and it seemed to work without noticing any issues. we loaded as carefully as possible without slamming it around, etc, into one of those home depot rental trucks and stapped down very tightly for the 20 mile drive home.. not a very bumpy trip at all.

i know these tvs are delicate so i did my best to be very careful.

we got it home and fired it up... the red gun is way out of alignment.. probably about 2-3 inches off. I opened up the tv and nothing is visibly loose, etc. I cleaned out some cobwebs, cleaned the mirror, gun lenses and inside of the screen (filthy!) and buttoned it all back up.

this tv has an 'auto focus' for convergence but no manual convergence i could find. when i run the auto convergence it moves the red signal closer to the center + but never converges it fully. the numerous times i've run it i've gotten the following error codes... E12R, E17R, and E13R

after about 30 minutes of being left on last night on the red image seemed to have some horizontal jitter in it. almost like some electronic noise or interference and was wavering from 1-3 inches off convergence to the right.

strangely when i turned the tv off.. then back on again.. the picture was clear as a bell with no convergence issues.

i left it on overnight and when i woke up it was still fine after about 6-8 hours. I turned it off and went out for the day... came home about 4 hrs later and it's back to a convergence issue again.

i kept cycling power with no change and then out of nowhere the image converged itself. an hour or so later.. while watching the TV the convergence went off without warning and cycling power didn't seem to have any effect.

i'm assuming convergence on this isn't a matter of physical positioning of the guns but more a circuit board controlled thing. maybe the red board needs replacing?

this is a longshot but does anyone have a service manual for this tv or an idea of what could be causing the issue and what it will cost to have fixed? also.. what should i look for when calling around for a service technician if this is not something I can fix myself (i do have some technical ability and not adverse to getting in there and swapping parts if possible.)

thanks! keith.

Reply to
Keith in NJ
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Likely just bad solder connections at the convergence IC's. Rono.

Reply to
Rono

i found this page

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and it's showing some similar issues with a covergence IC (IC506) being the culprit.. i'd assume this is possibly the one you're talking about.

without a schematic, anyone know where i could locate this chip? not sure if it's on the crt yoke itself or somewhere else (on the mainboard?)

thanks. k.

Reply to
Keith in NJ

There should be two large ICs mounted on a big heat sink. The ICs probably have a number that starts with STK. They are a common problem with virtually all projection TVs. Andy Cuffe

snipped-for-privacy@psu.edu

Reply to
Andy Cuffe

It is highly likely that one of the yokes on the red tube is loose, and moved during the trip. Just look on the back end of the red tube and see if there's anything loose, tighten the clamps again after aligning the picture. Good luck.

Reply to
Ouch My Back!

yoke as in the yoke board on the back of the CRT? i'll reach in there and see if it's loose. what is strange though is that moving the unit or tapping the body of the CRT has no effect on the picture which i would assume it would if it were loose.

question... i mess around with arcade machines and monitors so i have a little experience with discharging monitors and staying clear of the annode cap and wire, etc... but on this monster... what exactly am I watching out for? i guess i could just trace the wires from the flyback and steer clear from there. :)

also.. i located the 2 "stk" IC's on the heatsinks. they're held in with 2 screws so i'm assuming they're socketed unless that's what holds the heatsink to them.

  1. where would I get replacements for these.
  2. doesn't each gun have individual convergence circuitry?
  3. where (if anywhere) can i find the service manual for this tv?

thanks for all the help so far. i'm confident i'll get this fixed.

k.

Reply to
winner

i'm assuming this is the IC you're referring to is this one... IC STK392-020

i just found a source for it.. is $32.38 each from partstore.com a good price / source for parts?

i guess i should replace both of these ICs?

is there any way to pinpoint an issue like this before simply swapping out parts until it's resolved?

thanks.

Reply to
winner

Hi Winner...

Proj TV's aren't in my experience, given that I retired before they existed (at least among common folks), so all I have to offer is a gut feeling, but...

Before I invested very many dollars on a by gosh and by golly gamble, I'd be more interested in doing simpler checks.

Is it at all physically intermittent? If you're safe and comfortable operating it open, does anything anywhere respond to gentle taps with the handle end of a long light screwdrriver?

If the yokes are plugged in, I'd like to unplug and re-insert them a few times (obviously while off). Maybe even a puff of contact cleaner on them.

Probably do the same with the crt neck plugs.

Might like to use a magnifying glass to look at the solder condition around those areas that are subject to heat... carefully reflow solder on any suspect areas.

Could be worthwhile checking esr on power supply caps...

Just an old guy's two cents worth.

Take care, and be safe.

Ken

Reply to
Ken Weitzel

thanks ken. i'm a pretty common sense, check the basics and go by process of elimintation first kind of guy.

i have a couple of more physical things i want to check before I start swapping ICs and such.

this morning before i left for work i took another look at the mainboard just to see what's socketed and what's not... i see a few boards in there I want to pull and reseat as well as some of the connections.

before i can really see anything though, I'm going have to figure out a way to get 4-5 years worth of dust off the board without simply blowing it all over the place.

maybe one of those little vacuums with the brushes.

yeah.. before i order $70 worth of ICs i'm going to get in there and check the basics again.

thanks. k.

Reply to
winner

so i visually checked everything out tonight. then with the tv on i lightly tapped a couple of the heat sinks and the red crt neck board, etc and there was no visible change in the red convergence.

i'm going to call around to a few places tomorrow to get estimates on repair... can anyone give me an idea what i might be looking at $$$ wise so i don't get ripped off.

thanks. keith.

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Reply to
Keith in NJ

Try resoldering the IC before you go throwing parts at it.

Reply to
James Sweet

I think you mean the neck board, and no that's not the yoke, the yoke is the coil of wires on the neck.

Reply to
James Sweet

yeah. neck board.. sorry. i get the naming mixed up. coincidentally, i just adjusted the convergence on my ms pac man machine last night.. what a pain.. i wish arcade monitors had a 'magic focus' button on them. lol.

k.

the

Reply to
Keith in NJ

There's a few devices that slide onto the tube like 3 rings on one finger, These aim the picture via magnetic means to their precise landing on the screen, the convervence IC's taylor the signal to control exactly where the picture lands. There's a small magnetic ring assembly, a convergence yoke, and a main yoke, The yokes are windings of copper wire on an iron frame. They are secured with something similar to hose clamps about midway of the CRT tube. They would be installed by removing the crt board at the end, and sliding them onto the glass crt tube like a ring, they should not turn easily, often times the heat from the crt will cause plastic to get brittle and crack which will happen when moved. There could be bad solder connections at the convergence IC's also which would cause identical trouble. I kind of disagree that moving a set would cause the convergence IC's to fail, unless they failed as a result of a bad connection which was caused by the move. I would check the connections on them. Their failure is common though and would not be surprising. the other suffixes w/ a higher number are higher rated. ~010= crummiest ~030= best. I found them on ebay. and google provided spec sheets

Reply to
Ouch My Back!

by suffix i'm assuming your referring to the last 2 numbers on the convergence ICs... IC STK392-020 in this case "20".

another question is.. if there's 3 guns.... there's only 2 convergence ICs.

actually.. i thought about this.. on a regular CRT.. green is the center and red an blue converge on that.. is rear projection similar?

and if so... i'm assuming 1 IC controls red and the other controls blue.

that being said.. is there any way to tell which is the RED convergence IC? or am i completely incorrect in my assumption.

thx. keith

Reply to
winner

woohoo! success. ordered 2 new convergence ICs thursday from east coast transistor... ($8.95 each on ebay) look like OEM (listed as sanyo) and after a LOT of sweating over the board laying on my stomach because i was afraid to pull the fat red flyback cable... (it seemed like it was soldered or something in there because i pulled HARD on it and it didn't budge).

i managed to get the 2 chips desoldered off the board and the new chips back on... new heat sink compound and a pretty decent solder job if i don't say so myself. (first time i've done any PCB/IC work). put it all back together and BAM! (not literally) but BAM... perfect picture.. only maybe 1/8 inch out of convergence.. ran the auto focus and it was dead on!

really excited since i only paid $300 for the tv and about $30 for the chips (with next day shipping).

thanks everyone for the help!

k.

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Reply to
Keith in NJ

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