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

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Flux or no flux for new chips?

Is it necessary to use flux when re-soldering the new ic chips to the circuit board?

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Yes, flux helps soldering joints and makes it shiny and proper joint.

Posted on Sep 12, 2009


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During a storm a bit ago all the HDMI ports stopped working I am looking to fix them finally and wondering if anyone can help w a part # and instructions.

A basic understanding of electronics helps. I would look inside on the board and follow the traces from the hdmi back to the chip that feeds it. It would likely be an ic that has a voltage regulator in it as well as something to convert the serial port data. Write down the numbers on the chip and go to or phone an electronics parts supplier in your area and they will consult a cross reference manual to see if an after market version of the chip exists. If not they will order the original. Once you have the chip, you will need a decent soldering station ($100 or so) and a solder sucker. The solder sucker is used to desolder the chip or component slowly. Don\'t overheat the component but desolder as far as you can. then wiggle each leg one at a time until it breaks the remaining solder. If it does not wiggle off heat it again then wiggle it. Once all unsoldered gently pry out. (any other attempt to desolder without a solder sucker will damage the printed circuit traces) Before removing the ic verify which pin is pin 1. It may be printed on the board or a corner of the chip is marked somehow. Place the new chip in with pin 1 in the proper location. Use hitech solder that is hollow and contains flux on the inside to resolder. If the wrong solder is used the flux may attack the components and it will fail within a year (plus or minus). I would suggest finding someone who already does some electronics to assist you or to do the whole job.

Nov 18, 2013 | Panasonic Televison & Video

1 Answer

Solder question on NV5929u

There might be a lacquer over the completed circuit Board or it might be left over Flux . Flux is used to ensure solder joint is clean. Some solders have flux in them. Be careful of heat don't apply to much heat to board as it will damage the copper tracks. Are you using Solder wick or a desoldering station or suction solder device to remove the old solder ?

Oct 13, 2017 | Gateway NV5929u PC Notebook

1 Answer

I have a 1998 dodge grand caravan and my gauges won't come on

Im a computer Geek, not a car mechanic; My mechanic took the Guage Cluster Out and Insisted: I NEED a new one; Not True and Its a V.E.R.Y. Easy fix.

1.Remove Srews.
2.Unplug the main instument panel power supply plug.
(there may be a few bulb sockets that need to be disconnected, as well).
3. Don't Bother Examining the Contacts, Opposite the Plug In Socket.
4. Heat a Soldering Iron (Buy a Cheap 9.99 Soldering Iron, Solder, Flux) kit
(sold at Radio Shack; You want the thinnest Solder and USE THE FLUX. Not using flux, and/or 'cold soldering' is most likely the reason the solder cracked).
5. The cracks are so tiny you cant see them, all of the time, even under magnifier, so just brush, or dip your finger into flux and smear it over the 8 or 10 pins.
6. Heat one by one until original solder melts on each of the Power Socket Pins.
7. Let Cool, Wipe Clean..
8. Flux all Contacts Again,Flux heavily, heat an extra thin solder on the tip of the iron, not on the circuit board and try to drip a small blob of solder onto each of the your 8 to 10, or so, etc. contacts.
11. Make ABSOLUTELY CERTAIN, no 2 contacts are touching each other; if so, melt the solder off of one or both of the two touching one another.

I am A computer repairman who has made a small, side business, of soldering contacts, on guage clusters, for as many repair shops, in my community,who wish to pass savings onto their customers. I charge $25 per and hope the shop owner passes their savings onto the consumer.

So Far? 95% of the clusters i have soldered, were repaired by this method. Its so reliable: if It doesn't work, there's no charge~!, if any questions

Sep 17, 2011 | 1998 Dodge Grand Caravan

2 Answers

How to replace convergence ic on rear projection hd tv.

Panasonic convergence instructions for repair
What you will need;
Two new STK-392-110 convergence Ic?s
Liquid solder flux
Desoldering braid or wick
A good soldering Iron
Some denatured alcohol
A small toothbrush
A Philips screwdriver or screw gun to REMOVE SCREWS
  2. Remove back cover of TV set.
  3. Remove entire front speaker grill on set(it pulls off and may resist being removed)
  4. Locate and unplug speaker wires (they are plugged into the main circuit board).
  5. Locate three cables with wires that come from the Front keyboard?two of them have to be unplugged from the main board(all plugs are different s but note where they go)
  6. Remove 2 long philips silver machine bolts from the front of the set (behind the grill).
  7. Remove 4 more in the back of the set; two are located at the extreme back edge of the plastic frame and hold the chassis down; two more are located on either side and also go straight down; note which are which and set them aside.
  8. Using gloves pull the entire metal box (it is called a light box) out of the set; there are hand holds on either side?careful as the metal has sharp edges.
  9. Remove the box from the set and locate the two Convergence IC chips; they are located on identical metal heat sinks with fins and they should have the STK-392-110 number clearly printed on them in white (they are black)
  10. Turn the light box over on its side and UNSOLDER ALL 18 PINS ON EACH IC. It is a good idea to apply liquid solder flux to the pins on both chips now. I recommend using a de-soldering braid for this?get all the pins completely de-soldered.
  11. Inspect the dozen or so light blue resistors in front of them; most are marked 2.2 ohms?if any are white in the middle you will need to replace them at the same time; best way is to check all of them like checking a fuse----they protect the set if one of the STK?s shorts in any way.
  12. With the STK?s completely unsoldered turn the box upright and remove the two screws on each IC. If the chips have never been replaced you will need to tap them loose with a putty knife or flat bladed screwdriver.
  13. Remove both IC?s.
  14. Apply heat sink grease to the two new IC?s and install them one at a time; this part can take some time and it is important the pins on the new IC?s are perfectly straight---once you get them in, Hand tighten both the screws on each IC---do not use a screw gun?you can strip the screw holes out. Clean the bottom of the circuit board where the chips were soldered with some denatured alcohol and apply liquid solder flux to all the pins.
  15. Presuming you have already found/replaced any bad resistors turn the box back over and solder carefully both of the two new IC?s in, --do not short any of the pins to each other when you do this and when you are done it is a good idea to take a close look at both to make sure all pins are soldered and not touching each other with soldering you have just done. I suggest you do clean the pins on the bottom of the circuit board again with denatured alcohol.
  16. Slide entire light box back into the cabinet.
  17. Reconnect the plugs you removed when you removed the box. At this point take a lens cloth or a paper towel with glass cleaner sprayed on it and clean the three large black lens-if they are dusty the picture will be darker and not as clear as is should.
  18. Position the box so it is all the way in place and none of the wires or plugs are pinched.
  19. I usually at this point turn the set on before I replace the Six bolts that hold it in?2 from the front and the four in back----this way if you have a problem you can remove the box faster.
  20. If the set comes on and now has normal Convergence go into the customer menu and adjust the convergence in the multi-point mode----CAREFUL! THE FIRST OPTION this set usually offers is a green cross in the middle of the screen?do not adjust Green!
  21. Once you have the Red and Blue in the center adjusted find the second convergence mode---it will give you 8 or nine points on the screen with instructions on how to change from blue to red---use the original remote with the thumb wheel or cursor buttons to adjust.
  22. NOTE: SOME of these sets need to have the Convergence adjusted in first: full/4:3 and second in the other two zoom/wide zoom and third on the HD input with a HD signal coming in. There is also an option at this point to go into the Technical menu and fine adjust the convergence all over the screen?if you need this I can give you instructions based on the model you have?most of the time adjusting the set in the customer mode will produce a good result.
  23. I know all this may seem complicated to you, but this repair should take about an hour or so and just take your time when you get to adjusting the set.
  24. If all looks good turn the set off and Unplug it; install all 6 of the chassis bolts back; replace the back cover and the Speaker grill and plug the set back in.
  25. You may find it useful to go over the convergence Adjust again?to get all the points as good as you can. There is a hidden Tech menu that will allow a finer adjustment of the entire screen----it is somewhat difficult to access and there are a lot of buttons on the remote that then do different things.
  26. Most of the time adjusting in the customer menu will give you a very acceptable picture.

Jun 07, 2011 | Panasonic PT-51HX41 51" Rear Projection...

1 Answer

I reflowed my motherboard but didn't flux it. the ylod was fixed for around 3 hours. it has come back on. am going to try and reflow again tonight. should i flux it if so where do i put the flux. also is...

Hi there. I use flux every time I do a reflow. The reason for this is that it helps the molten solder flow much better and stops oxidation of the solder which can cause bad solder joints. The whole point of a reflow is to "mend" the hairline cracks that have appeared in the solder under the GPU and the CPU. Without flux this is harder to do. As to where you put the flux, you need to actually put around 4-5 drops on one side of the GPU and CPU and then tilt the motherboard so it runs underneath the chips. Do that for each side. Do not worry if the flux goes on other components, if you use "no clean" flux this is fine and will not do any damage. You basically need to make sure that the GPU and CPU are thoroughly "wet" underneath them where they are soldered onto the motherboard.

If a second reflow does not work or the fan speed increases to maximum after only being on for a short time then it is highly likely that the GPU or CPU have actually been permanently damaged from either the reflow or the original overheating. Only a replacement is going to fix this.

Also make sure you hold the air gun about an inch away from the chips for around 20 seconds. If you have a heat gun you can set to around 300 degrees celsius, all the better. If your heat gun is one that does not have adjustable heat settings, be very careful how long you heat the GPU and CPU up for. More heat means less time heating the chips

Hope this helps

Feb 12, 2011 | Sony Playstation 3 (PS3) Console

1 Answer

Can I get replacement batteries for my Norelco 7735X shaver?

I have replaced batteries in several Norelco shavers, typically ending up with better end performance than with the original batteries.

Norelco shavers typically utilize two AA sized NiCad batteries with thin tabs spot welded on each end and the tabs soldered into the circuit board internally.

I have had best success with utilizing Sanyo Eneloop AA batteries, see, which are NiMH cells with low self-discharge (i.e. hold their charge for over 6 months) and are free of the memory effects and internal self-shorting problems of NiCad cells.

The key to successfully changing the cells is to leave the original solder tabs on the circuit board and utilize the edge of a single edge razor blade (with great care) rocked back and forth between the metal tab and each of the ends (one at a time) of the original batteries so as to cut the spot weld free from the original batteries while saving the tab.

A single razor blade should do the job, though the blade will now be largely ruined for any further use.

Next carefully flatten the tabs (will be a little deformed by the spot weld break strategy).

Next carefully tin both the tabs and the ends of the new NiMH cells with a small amount of solder.

This tinning is not easy unless you use this strategy: Utilize small drops of "Harris Stay-Clean liquid" soldering flux, a clear (looks like water) zinc chloride liquid flux, e.g. dip a tooth pick into the flux and use just the small droplet of liquid flux which runs off the tooth pick onto the metal. After the flux is where you want the solder, touch a heated soldering iron tip already coated with a tiny amount of rosin core flux for electronic circuit joint soldering to the pre-fluxed area and the metal will easily and rapidly tin with solder.

For the new batteries, use only a tiny droplet of Stay-Clean flux right where you want the solder and touch the costed and heated soldering iron tip to the battery for just 1-2 seconds so as to minimize chances for any damage to the new batteries.

Once happy with the tinning of both the (saved) original batter tabs and the new batteries, hold the new battery in position and briefly touch the soldering iron against the tabs to push it into the battery end and fuse the two areas already tinned with solder.

I does take a little practice to get the above and physical alignments correct. It is helpful, though not mandatory, to use a temperature controlled soldering iron (e.g. set to about 500 F) with a fairly small tip.

Be sure to keep the Harris Stay-Clean flux, even fumes sealed in storage (I usually enclose the Stay-Clean bottle in a clear screw cap larger bottle) because just invisible fumes from this flux on any nearby iron or steel surfaces, over time, will promote rapid rusting. The Stay-Clean is a great product, just be careful with it during handling and storage.

Jan 04, 2010 | Norelco 7735X Electric Shaver

2 Answers

Touch Focus Error

57h82 uses two STK-392-110 CONVERGENCE chips---you need to replace both and check all the resistors around them---an open resistor means one of the chips failed.

You can buy both chips on Ebay for less than 12 dollars plus shipping--they are black--about 2 inches wide, 1 1/2 inches tall with 18 pins each and the STK number will be printed on the face of them in white letters; You need a good soldering iron, solder, a desolder braid, liquid flux, heat sink grease, denatured alcohol, and the ability to get at them: they are mounted to two side by side metal heat sinks with fins.

Once you locate them and unsolder them and the heat sinks from the board--replace both after cleaning the bottom of the board with denatured alcohol--removes any flux and solder particles---apply liquid flux before you unsolder them--these sets use lead free solder and the flux makes it easy to unsolder them. Once they are removed check all the resistors around them---one open resistor and the repair will not fix your problem---install the new chips with heat sink grease on them and install each chip/heat sink back into the circuit board.

Apply more flux to all the pins on each chip and solder them in----good idea to clean with denatured alcohol again and take a close look to make sure all pins are soldered and not touching each other.

If you get this far and the set now seems to work you need to use the original remote for the set and adjust the convergence--either in the customer menu or access the tech menu and adjust it there.

A service manual will not do you much good for this type of repair--it is a hands on repair.

I do this here for free, so if this has helped you take a moment and give me a vote here.

If you have any questions or need help contact me by replying to this posting.


Sep 03, 2009 | Toshiba 57H82 57" Rear Projection...

1 Answer

I need to replace the DC jack on my laptop

Do Not Attemp to Replace the Jack Unless You Have Experience with Soldering... The Original DC Jack Must First Be Desoldered and Removed... You Need A Desoldering Pump or Solder Wick (braid) To Remove the Old Solder From The Jack Post Pins..... DO NOT ATTEMP TO RIP OUT THE OLD JACK!!!!! You Will Pull The Contact rings from the center of the motherboard out and render the motherboard useless...

Slowly and carefully Unsolder the dc jack, Remove it and Clean the board.... Very Important to Clean the Motherboard after desoldering the old jack.... You Must Remove all old Flux...

Then Apply a light layer of fresh solder to all the contacts on the motherboard....

Apply Flux paste to the New DC Jack Pins and a light amount onto the contacts on the motherboard....

Insert the new DC JAck Into The Slots and Apply Solder to all points on the underside of the motherboard....

Flip The Motherboard Back Over, To THe Side Where THe DC Jack Is,, and Apply Flux then a light amount of Solder To The Side Pins and Back Power Pins ...

Then Clean the Motherboard off again using an Electronics grade circuit board cleaner (found at radio shack) or a tiny amount of denatured alcohol applied to a paper towel .. THe Purpose is to remove any remaining Flux..... as this will just deteriorate the New Solder over time unless cleaned off...

Good Luck

Nov 17, 2008 | Computers & Internet

1 Answer

Have a philips magnavox 8p6044 c102

Hmmm... I dont know where to find those CTR Circuit boards I'll post my general post for you about what I know it has links to the manual and some other sites it may help.

how bad is it burned, did some chips go or just the copper circuit board tracers. you can use circuit board wire and solder it from point to point,
I had somewhat of the same problem with my IC board, I had a bad portion of the board where I had to build a new copper routing with circuit wire, the copper burned off when the resistor failed, you may need to do a little Frankenstein work on your board as a last resort... remember use a low 15 watt soldering pencil, use leaded solder, and USE flux!
however with all my work, I got it running but the IC board is still not running perfect. if you decide you cant fix the TV I would love to buy your IC convergence board from you.
GOOD LUCK! hope I helped...

Actually I have this TV and you need 2 Convergence IC's STK392-120's (120's and 150's will work) of course order 2 of the same type I'm using replacement 150's they allow for a little higher heat and were cheaper ALSO you need to replace the 12 resistors with 6.8 ohm metal film resistors, make sure they are metal film! don’t skimp out here I did and then they blew and fried my IC's and I had to replace everything again!

Great reference link that I posted pictures on, check out page 3

Where I got all my parts that worked:
Suburban Electronics

Manual Library you should find all you need here:

What you need:
(2) STK392-120 OR STK392-150 IC chips
(12) 6.8 Ohm Metal Film resistors
set of star screw drivers
15 watt pencil solder pencil, DO NOT use a high watt iron you will fry the surface mounted item.
good leaded solder, and flux

BTW if you don’t plan on trying this and are going to throw out the TV, I still need a IC convergence board for a 51MP392H/17 TV I'm fixing, I'm willing to pay S/H and buy your IC board that’s not been tampered with.

Nov 12, 2008 | Philips Magnavox 51MP392H Rear Projection...

1 Answer

White Screen

Verify that the digital cable is pushed into the back of the LCD- IF that solves the problem put a piece of scotch tape over both the connector and the receptable so that they stay connected. Notice I said Scotch.. Not generic or Chinese cellophane tape - They leave too much residue, and lose stickiness over time.

Suggestion 2: verify that the other end is bottomed into the logic board.

Suggestion 3: press on the square Genesis chip - bad contacts and solder may be the culprit and TEST. IF so. you will need some flux, solder wick, and a low temp soldering iron. And reflow the solder on the chip (maybe 164 pin flatpak) after reflowing verify no shorts are between legs of the chip. You MUST use flux! there is no way around it. It has a purpose and will eleveate additional problems later by not using it. Then clean and remove flux with Q-tip and Acetone. (if using nail polish remover, get the kind without anything extra like Vitamin C, and Aloe) Pure Acetone is a good flux remover, Alcohol will have you rubbing all day, and still leave residue. (use in ventilated room though)
You should be skilled at this before attempting repair.

Suggestion 4 If none of the above works - the logic board is dead and may need replacing. The chinese company that made the board is hard to deal with, and the website is almost non-existant - and should be one of these boards

Hope that helps

May 13, 2008 | Star Logic Computers & Internet

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