Riddled TV Repair Forum
Service Menu and Manual Schematics
 
   
 FAQFAQ   SearchSearch   RegisterRegister 
   Log inLog in 
Red Convergence Hitachi 50UX52B; Soldering Heat Sink   Goto page 1, 2  Next  
Post new topic   Reply to topic    Riddled TV Repair Forum Index -> TV Repair
 
Author Message
afterburner1



Joined: 24 May 2009
Posts: 7
Location: Houston, Clearlake, Texas

PostPosted: Sun May 24, 2009 2:22 pm    Post subject: Red Convergence Hitachi 50UX52B; Soldering Heat Sink Reply with quote

To KUhurdler
Red screen has crescent shaped distorted area on the top left half of screen (Red drops off about 6 inch on top left half of screen) and the red has vertically dropped about 1/2 inch on all other areas of the screen. I plan to replace the Conversion Amps, IK04 and IK05. Think that is the problem. Gave both a shot of Super Cool, but there was no change. Also cooled many parts in conversion area, but still no change. Would like your input on red problem and soldering

I haven't been involved in radio and tv repair for a protracted period. Last time I remember it was replacing 6L6 tubes in an older amp.
My question is on soldering. I know how to do it, but I have heard with transistors and small electronic parts you should use a heat sink. Taking the two chips off the board will not be a problem, but replacing them may require a heat sink on each lead. Is that true and how do you approach a heat sink? Do you just use a needle nose pliers or do you have another devise? And finally what parts require a heat sink when soldering?

I have taken pictures of the red distortion, but could not attach to this post also have 99 page service manual on set. Would be happy to send you both via email. Please send me a PM if you want either or both.

Thank you in advance,
Afterburner
Google

PostPost subject: Advertisement

kuhurdler



Joined: 28 Dec 2006
Posts: 2879
Location: Overland Park, KS

PostPosted: Sun May 24, 2009 3:08 pm    Post subject: Reply with quote

What you describe sounds like a convergence issue. So I think you are on the right track here. Make sure you replace all the amps at the same time (I think there are 2 with this set?).

Also, it is convergence (not conversions) as in 3 colors that converge onto one screen. (I fixed your title so google searches will find this thread)

Regarding the heat sink... I'm not fully sure we're talking about the same thing.
1. You'll need to remove the old chips from their heat sinks, which is typically a mechanical connection, such as a threaded screw. Heat sinks are just large metal objects that help exhaust the heat from the semiconductors. They "sink" the heat from the chips.
2. You'll then desolder (or more accurately remove the solder from) the old convergence amps. I use a solder sucker for this, but you can also use a regular soldering iron with some soldering wick, which is basically braided copper wire.
3. Then solder the new amps back onto the circuit board.
4. Clean the thermal gunk off the old heat sink and apply new in its place.
5. reattach the heat sink using the same screws that you removed in step 1.
6. Enjoy your TV.


Hopefully this gets us on the same page. If not, please respond.


Last edited by kuhurdler on Wed Jun 03, 2009 7:35 am; edited 1 time in total
afterburner1



Joined: 24 May 2009
Posts: 7
Location: Houston, Clearlake, Texas

PostPosted: Sun May 24, 2009 4:05 pm    Post subject: Same Subject Reply with quote

Convergence/conversions: She went to KU; I went to Nebraska. They dont teach that "good" there!

Thanks for the reponse and making the changes; I do appreciate it.

I am glad we are congruent on the repair. The heat sink perhaps was not a good term. What I am concerned about is damaging the replacement part from soldering heat transfer upon installation. I think some heat transfer protection is required when you solder transisters to a board. I was wondering if that is important with chips and if it is what is the best way to protect it.
I will get the pictures and manual to you post haste
kuhurdler



Joined: 28 Dec 2006
Posts: 2879
Location: Overland Park, KS

PostPosted: Mon May 25, 2009 8:01 am    Post subject: Reply with quote

kuhurdler



Joined: 28 Dec 2006
Posts: 2879
Location: Overland Park, KS

PostPosted: Mon May 25, 2009 8:07 am    Post subject: Reply with quote

Ahh I get it. Husker fans... the N is for knowledge.

Just don't leave the soldering iron on the solder joints any longer than you have to. Melt it, and get off of it.

It does take some experience to keep from ruining the traces on the circuit board when you suck the solder off. But even if you ruin a few, you can probably fix it with some short jumpers to another part of the board. And your not really worried about ruining the OLD chips.

When you solder it back on, you just melt the solder and get off. If you don't sit there and cook the terminals it won't hurt it. The chip doesn't even get warm to the touch when you get really good at it. Part of that is because of the long metal leads on the chip itself.
Google

PostPost subject: Advertisement

afterburner1



Joined: 24 May 2009
Posts: 7
Location: Houston, Clearlake, Texas

PostPosted: Tue Jun 02, 2009 8:43 pm    Post subject: Same Subject (TV Fixed) Reply with quote

Checked all resisters in the Convergence Amp circuits; all were good. Replaced the two Convergence Amps. Original stock number was STK 392-110 but read on the internet that 392-150 had better longivity and handled heat better. Also add a small 12vt fan to blow on the heatsink, and another to use as an exhaust from the back of the set. Wired into the sets 12volt circuit to run fans. Not a good idea because 12vts appears to be present when the set is pluged in and and in the off position. Fans run all the time. Termporally fixed that with a wireless electric plug that turns off the power with a remote. Will get a better fix later. Right now I have a remote to turn the power on and a remote to turn the set on.
The most remarkable thing was the picture. As you can see above the red convergence was way off. After turning the set on, I could not believe the convergence alignment; it was perfect, not just perfect, but 100% spot on!
I appreciate the assistance given, and suspect I saved about $400 doing the repair myself. Just wanted to say thanks and share some info with you
Afterburner

JUST ANOTHER NOTE: I WOULD LIKE TO FIND THE ORIGINAL REMOTE FOR THIS SET. THE REMOTE IS A HITACHI CLU 612 MP. IF YOU HAVE ONE AND WOULD LIKE TO SELL IT, SEND ME A PM, PLEASE
kuhurdler



Joined: 28 Dec 2006
Posts: 2879
Location: Overland Park, KS

PostPosted: Wed Jun 03, 2009 6:49 am    Post subject: Reply with quote

Congrats on fixing your own TV.

I've seen the fans put on those heatsinks before. If you do that, make sure you open it up and blow the dust off regularly. Those fans will significantly increase the amount of dust that attaches to your heatsinks.
In general, I wouldn't recommend it. Someone who knows way more than I do about engineering sized those heatsinks to radiate the heat from those chips.

with that said, if you're wanting to incorporate the fans to work with the on/off switch, get a cheap relay. size the relay coil according to whatever switched power source you can find.
afterburner1



Joined: 24 May 2009
Posts: 7
Location: Houston, Clearlake, Texas

PostPosted: Wed Jun 03, 2009 8:57 pm    Post subject: Same Subject Reply with quote

Thanks for your comments. All good information
Thanks
afterburner
afterburner1



Joined: 24 May 2009
Posts: 7
Location: Houston, Clearlake, Texas

PostPosted: Wed Jul 08, 2009 1:17 am    Post subject: followup Reply with quote

Haven't wired in relay for fans. Believe I will need a 117vt relay and have it actuate the 12vt fan circuit. Kind of a setup similar to an automobile starter circuit.
Don't know if you are aware of heat sink, but it is a finned block of aluminum about 8" x 2" x 1.5" and when it gets hot it is untouchable. I would estimate well over 150 degrees. I guess there is a tradeoff vis a vis dust and heat, but I would go for the latter rather than the former. Heat and electronics are bad combinations and disipating this heat may increase the longivity of the other components of the set.

Just some followup thoughts.
Thanks again,
Afterburner
kuhurdler



Joined: 28 Dec 2006
Posts: 2879
Location: Overland Park, KS

PostPosted: Wed Jul 08, 2009 5:56 am    Post subject: Reply with quote

You found a 117 V AC source that is switched?
Display posts from previous:   
Post new topic   Reply to topic    Riddled TV Repair Forum Index -> TV Repair All times are GMT - 6 Hours
Goto page 1, 2  Next
Page 1 of 2

 


Disclaimer: All information provided by RiddledTV is strictly for information purposes only. Please observe all warnings displayed on your electronic
devices. This information should only be used to help diagnose work, and all service should be performed by a qualified technician.
Privacy Policy       Copyright © 2020 RiddledTV.com       Advertise on RiddedTV.com