I was told that my convergence ic's need to be

Oct 28, 2009

- First---this set uses two of the STK-392-120 CONVERGENCE CHIPS---they are side by side on metal heat sinks on the left board as you look from the back of the set.

The 6.8 ohm resistors should be in front and to the left of the heat sink towards the front of the chassis---all of them have location numbers on the top and bottom of the board--they are R3149-R3159--and are 6.8 ohm 1/2 watt resistors--you should be able if you look at them close to see any that are white or discolored are gone--best is to check all of them like checking a fuse.

As far as the chips go---on Ebay select search, then advanced search, then search by seller---look for sewsales55 he has the best prices on the chips and gives a 6 month warranty. If you find bad resistors any place (even radio shack) should have them---look and check them first.

Do you want to know the best way to get at them? Do not try to remove the large board, it can be done but you better mark all the plugs so you know where they go---this set uses torkes type screws.

The quickest way is to put the entire chassis with the plastic frame into the service position--I can tell you how to do this.

Aside from the chips and resistors you need solder, a de-soldering braid, some liquid solder flux, and some denatured alcohol or acetone to clean the bottom of the board when you remove the chips.

You also need some heat sink compound to put on the new chips before you install them---they are held in with metal clips that snap out.

Do a visual on the resistors and if any are discolored you will know how many you need.
Let me know if you want to know how to put the chassis into the service position.

REGARDS, SD TECH

Oct 28, 2009

- I am in California---going to sleep in about 30 minutes--no pay is required.

With the back removed, there will be six torkes--three along the back edge of the plastic frame--three more right to left near the middle of the frame.

Once you get them out you can pull the chassis back a little and lift it up.

You will notice a slide board just below the lens--pull it out and look at the two slots on either side that it slides into--they should have philips screws in them--remove the screws and wood pieces--note which is which.

with them out and the chassis unbolted you should be able to slide the entire chassis back and tilt it up--you may have to release a few cables from ties---it will be a tight fit to get it back and up--move slowly--

Depending on exact model there may also be two pieces of wood on either side with screws you have to remove--on sidewall of set---if they are there you have to remove them to get enough room to lift the chassis up.



Once you get the entire chassis up with the bottom of all the boards facing the back of the set you can unsolder the chips--check the resistors first and if you find any bad when you get the chassis up unsolder them first--It will be a tight fit to move the chassis up and down--

Coat the pins on the chips and or resistors with liquid solder flux--it will help you to remove the solder--these sets use lead free solder--it does not like to come away easy--\\

Once you get both chips and or any resistors unsoldered put the chassis back down--clean the bottom of the board after you unsolder any parts--it will make it more easy when you solder the new parts in.

With the chassis back down--unsnap the clips on the chips and remove each of them--same with any resistors you replace


Clean any old grease off of the heatsinks--apply new grease to each new chip and install--important the pins are perfectly straight on the new chips or you will have a hard time.

When you get a new chip in---hold it down when you snap the band back--it will try to lift up--get it all the way down and snap the band back on.

With both chips in and the snaps in--replace any bad resistors--once done tilt the entire chassis back up---apply liquid solder flux to the chips or resistors and solder every pin back in--when done clean again and inspect all soldering to make sure you got everything and did not short any pins to another pin etc.

With everything soldered put the chassis back down and slide into place.

Cross you heart and plug set in and turn on to see what you have--it will either work or toast a resistor in the same area---the point here is the only way to know is to replace the chips and see what you have.

If you end up with a working set---I have more information for you--These sets have a hidden menu to adjust the convergence all over the screen---if you are going to have a HD connection to it--you will have to adjust the convergence in the normal and also in the HD mode--they are separate.

You need an original working remote for this---adjusting in the customer menu will give you an ok picture but adjusting in the TECH mode will give you a better picture.

By the way--when you have the back off--at some point wipe the three large black lens with something to clean any dust off of them--if they are dusty--picture will be darker and somewhat dull looking.

Keep in mind I am here to help you----got emails today from 2 people who did this that had great results-----they both wanted to send me money but I told them no---just happy to help people here.

Yell if you need help, I am here most of the time--wife laughs at me.


SD TECH

Oct 28, 2009

- NEVER MIND-- buy her some flowers and surprise her--there is no upgraded replacement for the chip this set uses--stick to the original type--if it works the set will not have the same trouble for 5-8 years.

stk-392-150 does not replace the stk-392-120.

Going to go get some sleep here, good night.

SD TECH

Oct 29, 2009

- FIRST: the resistors have to be 6.8 ohms , not 680 ohms or 68 ohms---do not put the wrong ones into the set.

SECOND: ANY OF THEM THAT ARE BAD CAN BE TESTED LIKE TESTING A FUSE---NO READING ACROSS THEM MEANS THEY ARE BAD---any open ones that are bad will be somewhat discolored in the middle---white looking----check them first---if you are lucky none are bad---that is a good thing.

As far as soldering goes---with some liquid flux applied to all the pins on each chip use the desolder wick to remove the solder---do not force the iron or you can damage the foil! This set uses lead free solder and it may not unsolder easy---take your time and if you have to apply more liquid flux until you get all the pins on both chips unsoldered.

keep the tip of the iron clean with a wet sponge or wet rag---clean tips solder better.

Make sure when you install the new chips you apply heat sink compound to them first--the pins on the chips have to be perfectly straight or you will have a hard time getting all 18 pins in.

SD TECH

Oct 29, 2009

- FIRST: YOU CAN CLEAN THE BOARD WITH ACETONE AND A TOOTHBRUSH TO REMOVE ANY EXCESS FLUX.

SECOND: HEAT SINK COMPOUND IS A WHITE GREASE FOR MOVING HEAT--NOT AUTOMOTIVE GREASE--RADIO SHACK SHOULD HAVE IT--HEAT SINK COMPOUND. REMOVE ANY OLD COMPOUND FROM THE HEAT SINKS AND CLEAN THEM---careful this stuff stains hands and clothing so wipe it clean.

THIRD: IF NONE OF THE RESISTORS ARE DISCOLORED---most are light green in color---just check them all with a meter---just like checking a fuse---a 6.8 ohm resistor should read just like a fuse--a short. A bad one will have no reading across it.

IF YOU GET THE SET WORKING LET ME KNOW AS I CAN TELL YOU HOW TO GET INTO THE TECH MENU TO FINE ADJUST THE CONVERGENCE ONCE THE SET IS REPAIRED.

You may not like this but this set will need to have the convergence adjusted first in the regular and then in the HD mode---if you have HD you are going to have to adjust the convergence twice--once in each mode.

FYI: with the back off if you get the set working wipe the three large lens clean with a lens cloth or a paper towel with glass cleaner sprayed on it---if the lens are dusty the picture will be darker or less distinct than it should be---annual cleaning of the lens is a good idea and easy to do.

SD TECH

Oct 29, 2009

- JUST CHECK THEM IN THE RESISTANCE MODE--ANY OPEN ONES WILL TEST OPEN- no need to just replace them all--just replace any that are bad.

SD TECH

Oct 29, 2009

- if you get a beep, it means they are good--no sound means open or bad--replace the chips and see what you have.

SD TECH

Nov 24, 2009

- You are right, if it is a AC fan it will cause problems. Just forget about it. The reason the chips fail is after several years the heat sink grease dries out from the heat. A fan is not going to slow this down. Be prepared every 5 to 8 years to have to replace the chips---cheaper than the electric bill for a fan running for 5-8 years.


SD TECH