Help anyone!!!!!!
I am an electronic technician and I have a Pioneer that is 6 years old, back when 480p/1080i was CUTTING edge!!! The problem is this: last year the thing died when I pulled the plug while it was on. Simple enough, I pulled the covers, found the fuse and got another year out of it. Great, now last week the RED convergence went out and I thought I was screwed, but I found a link here that said the STK chips fix this 90% of the time, so I ordered them for $6 a piece plus $6 for shipping and got my TV back for $18!!!!! BIG PROBLEM NOW!!! My wife turns it on after I spend 2 hours optimizing it and it's dead... green light comes on flashes like 6 times and shuts down. I also noticed that the RED LED on the power board that says "power board fault", is on. I am assuming the intelligent fuse circuitry is reporting an overcurrent somewhere. So here is where I am at... I found that there are 6 Pots on the left of the TV, 3 for RGB focus and 3 for RGB gain. I turned down the gain and got my TV back, then I optimized it again and it is gone again!!! Damn!! So my question is this, is this TV getting tired, is there a quick fix, or what causes this problem?? I saw the manual for $15, but if someone out there can tell me that I am wasting my time/money on it, I WOULD GREATLY APPRECIATE IT!!! I repair CT scanners for a living and this TV is kicking my a$$!!!
I appreciate any input, thank you!!!
Ok, i have seen many pioneers. and i have seen this problem on pioneers after the convergence fix. I have pulled my hair out on this one too until I discovered the key. Pioneer i KNOW will allow you to over steer the convergence circuit, with this I mean that you can adjust the convergence beyond the current limit of the power supply causing it to fail. Over time Especially on pioneer, the convergence current will creep up by the user adjusting the convergence. The only way I have gotten out of this problem is to do a static centering convergence of the three crt’s. I came up with this procedure myself and it has worked quite well on pioneer. Here is what I do; first unplug all three convergence correction yokes, then turn on the tv (NOT THE MAIN YOKE!! you will burn your crt’s instantly if you remove this!) Then bring up the cross hatch, and adjust the convergence rings on the neck of each crt, for the best center convergence, I only look at the cross in the exact center of the screen and make sure it is perfectly converged. Then turn off the tv and plug in the convergence correction yokes, when you turn the tv on it will be way out of convergence, but when you are adjusting the convergence you are now lowering the current flow instead of raising it. If you look in the manual it will tell you to use the overlay and use the marks on the overlay for the static, but that is with the convergence yokes plugged in. I found that it is just a effective to do it this way. When you have the convergence yokes unplugged the voltage divider resistors will get very hot over time, so I suggest not to have the tv on for more than 10 minutes with the convergence correction yokes unplugged.One last thing, $6 convergence ic’s are not good, they are most likely the cheap reject ic’s and will cause you nothing but heartache. We tried the cheepos and have had nothing but pain. Get a good set. Also I suggest replacing your ic’s with stk392-180 if your set is using stk392-110 through stk392-150 use only stk392-180 this is a recommendation by pioneer tech support. If your set uses stk392-560 only stick with that ic.
no, you probibly need to change the ic's again, like i said the cheep ones will only give you trouble try mcm electronics, also there might be a blown glass fuse on the power supply board. Check that. then you need to do the static convergence so you will not overload the new outputs.
Power supply board is good. So maybe the chips fried or are overloading the circuit? OK, this is quickly a project I have to think about... do I start sinking money into a 6 year old TV, or just get a projector with 720p for $500... hmmm... Thanks, I'll prolly order the chips as a last ditch effort... at least then I could sell it for a few hundred and get my projector cheaper!!!
if you want my personal opinion, projection tv's are on their way out, eventually flat panels will be all there is. All projector types have one big problem dust, dust in the light engine will cause blotchy dis-colorations on the screen, and they currently can't be cleaned, they have to be replaced when this occurs. so i would think hard about what technology you want to invest in..
One more Thing! Do not forget to install new heat sink compound on the backs of the new IC's before you install them back into the TV set. I bet those cheapo IC's fried as zap said. I have seen this a hundred times. I like to order my IC's from here. http://www.electronic-repair-kits.com/index.html Good Luck
WOW!!!!! I am truely humbled by you guys!!!! Thanks sooooooo much!!! One of the BIGGEST problems I face at work is installing a component and thinking that it could NEVER be bad!!! Thanks for ganging up on me and making me trust in you guys! I ordered the STK392-180s from MCM and paid $40 and installed them with plenty o thermal paste, also replaced 4and5 amp fuses on power board. Fired it up, did a manual convergence and BAM!!! Everything is BETTER than before!!!! I watched "cars" with my son this morning and damn it was beautiful!!!! Thanks soooooo much guys, I'll never doubt word from this site again!!!!!
Ok, i guess I am NOT a TV repairman!!!! Please help!!! I replaced all the fuses and changed the chips to the STK392-180s used plenty o thermal paste and the TV was FLAWLESS for 2 weeks... NOW SAME PROBLEM!!!! Fuses blowing, and I am sure the chips are fried again... any input? What causes these chips to overheat? Is there a "magic bullet" resistor or maybe a leaky cap you guys have seen here? I don't have access to a scope, so i really can't get a read on any signals, but I am handy with a DVM and have plenty of those!!! So if there is something else I should be checking to protect the NEXT set of chips, please let me know! I heard of some 220uF that could be leaky, but I am not sure which of the 200 caps these specific ones could be. Thank you soooo much, just seeing it work again tells me you guys are a great source, but I'd really like the satisfaction of "FIXING" this unit for good! Thanks people...
Sorry to bump, but if no one has any ideas, can I at least get the schematics? I found/watched a transistor lose it's magic smoke, so I know I am at least replacing that!!! I think I have an overvoltage problem and I am guessing it's the red, always the red it seems... Anyway thanks for everything and I understand as a troubleshooter that any problem has 1000 fixes, but if you guys have seen any common ones, I'd love to hear it... even if it is as simple as replace the STKs again... I am half tempted to hang a 120V fan on that heat sink at this point!!!! Thanks, oh yeah send schematic to [email protected] and save me $15... Thanks!!!
I mentioned this before, on Pioneer televisions, it is possible to draw too much current through the convergence ic's because of digitally over steering the convergence. I have seen this before and you will keep blowing the convergence ic's until you lower the current going through the ic's. you do this by dis-connecting the the convergence yokes only, and adjusting the convergence rings on each crt for the center convergence only. then plug in the yokes and start the digital convergence based on the new natural centering that you have, you will now be lowering the current instead of increasing the current. if you want to monitor this use you amp meter and put it in-line with the power supply and you can actually see the current drop as you adjust the convergence, the ic you you saw smoke is probably the voltage regulator for the convergence ic's. I have fought this problem before on pioneer, and what I said is the only way I keep them from coming back into my shop.
I have used this on a few types of projection TV sets. When I install new IC's I will let the set play for a good 10 to 15 minutes and if the heat sink is getting really super hot, I will center the beams on the picture tubes.
Awesome, will try this. Thanks! So can I get the schematics? Thanks again
I meant the service manual... thanks again, but I'll take the schematics too if anyones got em!!!
Ok, so I found out the transistor I blew. It appears to be a C2878 sound limiting transistor. Does anyone have a couple I could buy?? The best I could find was a $75 minimum order, and an equivelent part, but then I read in Carver amp forums that the equivelents suck. So if you have a couple and could spare them, I would gladly Paypal your costs!!! Thanks...
I am sorry, I do not have this service manual man.
Ok, I reordered the STK392-180. I need help locating a transistor C2878. Doing some internet searching, it appears to be a noise limiter. Does anyone have one or know of an equivelent? I need this because I watched mine vaporize in front of me! So please if you have changed this part, or you have access to better search tools than I do, please let me know where I can find it.
One final question, How hot is hot? When I touch the heat sink for the convergence chips, how hot is acceptable? should I be able to touch it at all, or should I be able to hold my hand on it for a second or two? Is there a place where I can take a current measurement, because now I am in fear of blowing up my $40 fix every two weeks! The chips are warm, so is this acceptable that the heat is dissapating properly? The heat sink burns skin after 5 seconds. I actually am considering hanging a 12V fan in there, just to keep it cool... Thanks ALL!!!!!
current measurements are the most accurate. can you give me the location number on the board for that transistor, i bet it is used for a voltage regulator for the convergence ic's, if it is that is the one you want to monitor. remember to do a static convergence with the convergece yokes un-plugged. No need to install another fan, if you have your convergence set up correctly, you should not be burning up parts anymore. if it is fiexed correctly no modifications are nessassary.
I know this is frustrating, i have dealt with his frustration with Pioneer tv's before. But trust me if you get it set up correctly it will work fine and keep working. It took me a while to work out this procedure, The very first one i had i burned up two or three sets of these ic's if i remember correctly. Until i worked out this procedure to fix, and the tv has never come back in.
Q424, almost positive, I will recheck tonight, it sits right in the middle of the convergence ICs towards the front of the TV, that's why I watched it vaporize.
Now let me clarify because I have a Sony 51in with the same crap and the Convergence ICs fixed it. After watching TV for 20 min I go and touch the heatsink for the convergence ICs and it is hot to my fingers, like I can touch it for maybe 2-3 seconds. The Convergence IC's are warm to hot, so I am just wondering if this is normal, or if I have to worry about blowing these chips. I also notivced it seems like the right one (from the back) is a little warmer than the left. The image is perfect, I did a manual convergence and got the focus in to a pixel level. Just wondering if I can slap the covers on and call it good. I also did the "manual" adjustment on this TV, just to be sure, GOD it's beautiful!!!
The Pioneer has parts on order, 2 more 392-180s. and the transistor, which I am sure you are right about, but I will get the number positively tonight. Thanks soooooo much!!! I feel like this is an online center because you guys have been very polite, understanding and seem to have the same love for doing it yourself as I do!!!! THANKS!!!!
i found a Q404 that is a 2SC2878 that is the same part as a C2878 it is in the mute circuit for the convergence ic. so yea the convergence ic could have smoked that part.
Q404... THAT WAS MY SECOND Guess!!! I remember seeing that on the board yeasterday... Thanks!! Well It's much easier to find a 2SC2878 than a C2878!!! I can prolly get that at Radio shack on the way home tonight!
Here we are, new STKs IN, new 2SC2878 IN. Pulled Red, green, and blue wire off convergence boards on CRTs and I get no image. Installed 1 at a time and focus manually using the Green as reference. Done. Set TV all up, convergence is almost perfect, hardly any adjustment needed.
Went to touch the Heat sink for the STKs after 5 min of TV on and almost burned my hand!!! I KNOW these chips are going to fry in this configuration, so I need help with a voltage or current measurement that can get these things cooled down. Picture is great, but I doubt it will last long unless someone can tell me how hot that heat sink is supposed to get.
I have a Sony 51" sitting right next to it and after 2 hours run time, I can still touch the heat sink for 2-3 seconds...
Any help appreciated, I don't want to buy a 4th set of chips for this set... Thanks!
wait a minuite, you got no picture with all three convergence yokes pulled ???? Because with the convervence yokes in you cannot get center focus because the curent convergence will throw off the neutral beam landing.
ok, i wll see if there is a convergence re-set that will null out any correction when the yokes are plugged in, then after all adjustments have been nulled out, you manualy converge for center then adjust, i will look at the manual to see if that can be done.
Ok, when you do the convergence you will see the hex number at the bottom right of the screen, any number between 1FF and 200 , 000 is neutral that is the absolute center with no current adjusting that point. with the convergence yokes plugged in, adjust the center box only to 000 for all three colors, then use the centering rings to align the three colors up only on that center box, then proceed to converge to the green, you will then start dropping current, if you have allot of numbers near 1ff, or 200 this is causing allot of current flow. now you picture after doing the center convergence probibly will be wayyyyyy off but that is fine you now know where center is, just proceed to fix the convergence this way.
P.S. I never had trouble pulling the convergence yokes and keeping a picture on the screen, so this is somthing i have not encountered. but what i have said above will achieve the same goal.
you said "hardly any adjustment needed." - that is a problem, because i know the current settings you are using is drawing too much current. you need to be doing allot of corrections.
I am sure of this, also means that I need the service codes if you got em!!!! This sounds like a WIN here, I am all in on your fix, just the codes and I'll be set. P.S. I CAN give you guys props for fixing my Sony 51 inch, no problems yet, and 720 is soooooooooo excellent!!!! Thanks,
The codes are located in the bottom right of the screen, to get into convergence mode, there is a small hole on the left side of the control panel under the door in the front of the tv, get somthing long and stick it all the way down the hole and press the button in the hole, the factory convergence will pop up. there is no re-set that i can find in the manual. that is why i came up with what i said about setting then value to 000 for the exact center.
Ok adjusted all to 0, but by moving the green I shifted the grid, so did my best to tweak it back to a nice grid, then set Red and Blue to zero and adjusted the yokes, then did a convergence set up and centers were pretty darn close, had ALOT of work on red and blue but finally got a nice image. PROBLEM: after 5 min of on time, I cannot touch the heat sink. ANYONE HELP! Tell me if they get this hot, or if I need to adjust something else, I am afraid my $40 fix is going to become the cost of a service call fast if I don't nail this!!!
Thanks everyone, My Sony is still FLAWLESS and beautiful at 720p!!!!!!! Just gotta get this Pioneer running!!!
The heat sink gets hot, but how hot is too hot is to subjective. Take current measurements, that is how i did it. I think on this set, they are running pritty close to tolerance anyway, that is why i have had so much problem with this set. do you know how to test current ? if you are less than 75% of the fuse current rating, than you should be in the operating current range, that is a standard that is uesd to calculate current flow.
Hello again Guy's, I have the same TV and it blinks and chirps at me 5 or six times and goes to stanby when I turn it on. My question is,Can I take the convergence chips off the board and then try the set to see if it comes on? I know you can do it on some sets and if it powers on it tells you the chips are shotor something before the chips caused it to go out! I plan on working on it this weekend, so any and all help will be great! Thanks, Rick
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