to upgrade the ic chips or not to?? - Home Theater Forum and Systems - HomeTheaterShack.com

 
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post #1 of 9 Old 05-01-12, 10:08 AM Thread Starter
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to upgrade the ic chips or not to??

primarily i have come here to see what some experienced techs think of this idea. i have a panasonic pt53wx42f and i'm 99% sure the ic chips are bad. i have very limited knowledge about tv repair so please bear with me. i've read that i should go stock in some places but i've also read in more places to upgrade. my question is what should i upgrade to? they have have a few options of the stk392 xxx chips as well as stk394 xxx. oh and i'm currently using stk392 110 chips. any advice on the topic would be appreciated.

i suppose i should give a brief history of the set because i could very well be wrong about the ic chips being bad. an elderly friend gave the set to me after he got it and it wouldn't work. it wasn't hauled properly and that might come into play idk. you all might get a kick out of this or read between the lines. the set was given to him and when he got it, it was setting on a front porch out of service. the guy told him it worked but the color was off a bit (i have my doubts). my elderly friend (in his 70s btw) and a mutual friend hauled it on it's side due to some physical limitations and lifting. if they called i would have went and helped. idk why they didn't do that honestly. anyway they hauled the set about 10-12 miles laying sort on it's back and side. they did get me to help unload it though. well we get it in there and i thought it felt a little loose so i went to looking and someone evidently had been inside it and neglected to put most of the screws back in . don't know what happened or what they done. so we plug it in and fire it up. it came one and the convergence was screwed up as expected. after it ran a few minutes, it kicked off and only flashed the convergence code on the power led. could the back being slightly off make it do that? i done some homework and found the service manual online. then looked up the code and confirmed it. i returned with the info and he told me i could take it and try to fix it if i wanted to. me not being one to trun down something of that nature, i jumped on it. well i get it home (hauled standing up lol) and went to looking. i found a burnt resistor on r7056 (2.2ohm 2watt) and some fresh looking paste on the stk chips. i also got some screws for the frame/chassis lined up for reassembly.

any advice or tips would be greatly appreciated thanks..
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post #2 of 9 Old 05-02-12, 09:42 PM Thread Starter
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Re: to upgrade the ic chips or not to??

update:
i finally got around to pulling the ic chips the afternoon and i had a of a time. darned solder points were trying to come loose on one. it's not overly damaged though. i think it will be fine. i went over it with a continuity tester and it was fine. just the copper points are trying to come off the board. nothing was shorted and everything went to where it was supposed to on the board. the 2 on the end were connected (not by left over solder) and that worried me. the other one was like that as well. it was also a breeze to get off and is 100%. i would post an image but i have to few of posts to do that.

i know that stuff happens with to much heat and/or pressure but i was using a sponge to clean the iron regularly and it's only 30 watts. i didn't have to hold it on the or anything it just melted on contact and and i sucked it up with my bulb. i even went as far as to do a few practice runs on an old 478 emachine board i had laying around (and this isn't my first time with an iron in my hand). i didn't have the first issue with melting or removing the old. anyway i think it's going to work out.

the stk392 110s though.. i could tell by the paste that it was not done to long ago. it was thick but not baked. what i found more interesting was the chips. there were a few blackened spots on that that appear to have been burn marks. i have no doubts that this is the issue after looking at them. i'm thinking they were knock offs because the legs were a bit on the thin side and i can't see a factory sanyo chip getting burn marks or going bad to quickly. i don't know the exact history but i've changed enough compound on cpus and video card to know that it was on the fresh side. i would say about the compound on the ics were about as thick as a cpu compound gets after about a year or so. it wasn't bad..

moving on, if anyone has any experience with panasonic convergence amps/ic chips and upgrading, i would really appreciate the any advice. that's all that's holding me back.

i also got the original remote to so yay, saved me 20 +/- on the project
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post #3 of 9 Old 05-03-12, 08:23 PM
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Re: to upgrade the ic chips or not to??

The STK392-150 is the proper chip to use to replace the 110. Just be sure to use a reliable supplier.

I have never seen burn marks on a defective IC.




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post #4 of 9 Old 05-04-12, 12:53 AM Thread Starter
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Re: to upgrade the ic chips or not to??

thanks buddy i'll get those instead of the 110s. wish me luck. i'm not 100% sure the ics will fix it as i don't know the history or have any real experience with tv repair. i read the thread about ic replacement but being my luck, i would have the 1 set that blew up with a better ic in it. i also read about a guy who replaced 110s with stk 394 160s and it turned out they drew to much juice and wouldn't let him fully converge. he then put in the stk392 180s or 150s (i don't recall exactly what he used and downgraded to) in it and it worked perfectly. i was hoping to avoid that possibility. anyway i'm sure the 150s are about the same in terms of amperage draw and will no doubt do as good or better than the 110s. i was just to hesitant lol i guess i need to "grow a pair" and do it already.

the burn marks.. i could be wrong about what they are but that was what they appeared to me. it's not scratching off. it's right along the tops of the chips and along the bottom of one. it could have been crud baked on to. i'm fairly certain they weren't factory. i'll try to get a good close up and post it here or facebook (not sure about the post count, been counting). it seems when i get to working on something, it's never anything normal anymore lol. again thank you for the advice.
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post #5 of 9 Old 05-05-12, 07:05 AM
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Re: to upgrade the ic chips or not to??

Quote:
jerryrigg wrote: View Post
thanks buddy i'll get those instead of the 110s. wish me luck. i'm not 100% sure the ics will fix it as i don't know the history or have any real experience with tv repair. i read the thread about ic replacement but being my luck, i would have the 1 set that blew up with a better ic in it. i also read about a guy who replaced 110s with stk 394 160s and it turned out they drew to much juice and wouldn't let him fully converge. he then put in the stk392 180s or 150s (i don't recall exactly what he used and downgraded to) in it and it worked perfectly. i was hoping to avoid that possibility. anyway i'm sure the 150s are about the same in terms of amperage draw and will no doubt do as good or better than the 110s. i was just to hesitant lol i guess i need to "grow a pair" and do it already.

the burn marks.. i could be wrong about what they are but that was what they appeared to me. it's not scratching off. it's right along the tops of the chips and along the bottom of one. it could have been crud baked on to. i'm fairly certain they weren't factory. i'll try to get a good close up and post it here or facebook (not sure about the post count, been counting). it seems when i get to working on something, it's never anything normal anymore lol. again thank you for the advice.
The problem with the subs has nothing to do with how much current they draw. In fact, they are more efficient thermally when used in the right application. Any problems have to do with either needing to change resistor values, different pin configurations, or muting circuits. The current ratings are the maximum current that the chips can pass without blowing apart. These are operational amps, which will deliver current based upon the voltage input and the load applied.

The STK392-110 can be replaced with the -150, -120, or -180, if they are Sanyo parts. They are all functionally identical, other than the -120 has a higher current rating. Any other subs may or may not work.

More than anything else, problems with completing these repairs have to do with mistakes or things that people don't check. I outline what you need to know in the first ten posts of the convergence repair sticky, but invariably, people don't go into the detail of testing needed or don't get all of the connections right.




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post #6 of 9 Old 05-05-12, 10:01 PM Thread Starter
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Re: to upgrade the ic chips or not to??

i understand about checking things. i will no doubt be using your guide as a checklist and or walk through. very well written and thorough btw, good job. i will be using the 150s suggested. i hope is that the board is ok aside for the ic chips. lol i still haven't taken a picture of the marks on the chips. i did crack them open just to see if there was any visible signs of failure lol. nothing but oddly, they appeared to be the same as the as oems from what i saw in a google search for "how to tell a knock stk from oem stk". the only concern i had now other than the many possible failures points on the board is the places where the copper circuit came loos from the board. it only came loose in a few places and it's not bad and all checks out with the multimeter but is there a glue or something i can use to get them to sit in place better? they will solder and make connection as is but i would feel better if i could do something about it, ya know? either way it should work if my diagnoses is infact right about the ic chips. i greatly appreciate the advice given thus far and i am sure in the future it will help as well. as i have a good working toshiba already so that makes 2 in the home right now, plus i know a few who have the old crt sets like this and this advice/knowledge will go further than the initial set. just wanted you to know how much it's appreciated.. it seems you are one of the few who can give technical advice.

not to get off topic but i doubt i can contribute on this sort of thing but is there a place for htpcs? i retired my old tower to use as a htpc and found it very handy for web media (we don't even have cable because of it). would it be cool if i put something up with the benefits and advice on possible builds? that sort of thing i can give contribute to.
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post #7 of 9 Old 05-06-12, 06:24 AM
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Re: to upgrade the ic chips or not to??

Quote:
jerryrigg wrote: View Post

not to get off topic but i doubt i can contribute on this sort of thing but is there a place for htpcs? i retired my old tower to use as a htpc and found it very handy for web media (we don't even have cable because of it). would it be cool if i put something up with the benefits and advice on possible builds? that sort of thing i can give contribute to.
Look here:
http://www.hometheatershack.com/foru...media-servers/




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post #8 of 9 Old 05-06-12, 06:27 AM
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Re: to upgrade the ic chips or not to??

I am happy to share my experience.

High temperature epoxy is probably what you need to glue traces back to a board. I usually do not bother. I just scrape back the coating on the trace to expose the copper and lay extra solder to reinforce the joint and the trace.




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post #9 of 9 Old 05-16-12, 06:09 AM Thread Starter
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Re: to upgrade the ic chips or not to??

well it's working great. better than i hoped for. thanks for the advice on the ic chips and the tip on the board traces. you'll laugh but after i read that i went to the dollar store and got a glue stick and used that to hold the trace in place while i got it soldier. it can't go anywhere now and i checked my work with a multimeter after i got done. i also had to learn the hard way to about the service mode and more importantly to double check things that shouldn't be adjusted. you guys will like this. the tv i got with just a few screws loosely in place, i should expect what i found. i tried and tried (a couple hours) to get the tv adjusted. so much that i started investigating other issues. come to find out, the person who eugene (the elderly friend that gave me the set) got it from had actually messed with the lenses and had them not just out of focus but all 3 were loose. to think i thought i'm amateur at tv repair. is there even a step below amateur? oh well.. it's working and was a cheap 1080itv. funny though my pc is through svideo and the other stuff i have isn't hd. it might be time to get a blue ray player to take advantage of the tv's capabilities. again, thank you for the advice.
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