Trying to converge a Toshiba
TP48C71 big screen projection TV. On the grid, RG are converged but blue is way out- like 2 inches, and the front control barely even moves it.
I pulled the main convergence board PB3366-1 and I see nothing obviously wrong with it. I think the CONVER OUT board, PB3366-2 may be the problem though- its the one with the 2 big heat sinks.
Anyhow- I got online to get a service manual, and found one and downloaded it. Unfortuately there were NO diagnostic procedures in the whole thing! It refered me to another manual for TP48C50 , which the manual company and Toshiba say they cannot provide. Which is pretty bad to me for a set that isn't very old.
Anyhow, I've googled everything I can think of and I can't fund much on troubleshooting this problem. I have a dual-trace scope, DVMs, etc. - if I had a diagnostic procedure I could follow it.
Please don't mention warnings about being a qualified tech and all- I'm well aware from the danger and precautions both from my military electronics repair experience and my EE degrees. I ain't getting NEAR the HV sections!
Advice on the procedures, and/or where to locate more documentation is appreciated!
I think that at least some of the Toshiba models use the same convergence amplifier chip that I just replaced on my Panasonic HDTV set (they are trapezoidal ICs mounted to large heat sinks). They don't cost much to replace (I got mine for $5.99 and I just replaced them both - I don't know which one was bad).
Here is my blog entry about replacing mine, with before and after pictures of the on-screen convergence menus: http://cmpalmer.blogspot.com/2006/11/...
Thank-You, this is a very helpful reply. I plan to pull that board tonight. I suspect from what I've read that these are the most likely culprit. The poor reliability on these suggests a design problem- they had PLENTY of room to make larger heat sinks!
One question- where did you buy the ICs ? I'm not sure where to find them. Mine are Q701 / Q702 on the Convergence Out board (but in the parts list they are IC701 / IC702 ). These are
23904231 IC,STK392-020
Thanks!
I bought the ones for my TV from www.electronix.com, but they were the STK392-110. They had the best prices, but I don't know if they have the 020's or not.
Yes they have em- $6.99 each that's a great price. The local supplier wants $16 each and it takes them 3 days to get em!
Your
blog was excellent- nice use of photos. The last ones (pre/post
convergence) were impressive! I hope I get similar results...
I
was thinking of buying the 2 ICs, then replacing one and seeing if it
converges. My board appears to be easier to get in and out than yours
was.
Thanks again you are a nice person to assist me like this! I'll post my results hopefully we'll have a working TV soon!
S
Here is the datasheet for the 110: http://www.ortodoxism.ro/datasheets/s...
This explains why there are two ICs. Each IC contains three amplifiers, so there is a red, green, and blue amp for horizontal and vertical convergence.
Good luck!
Thanks this is very helpful too. I'll scope the outputs of the 6 amps and maybe sniff out which one is dead..
PS: Its definitely HOR convergence that's failing... I'll see if I can at least figure out from my schematics which is which...
S
Wow that company shipped FAST!
OK I replaced IC701which had the BLUE H amplifier. I left the other IC there.
Originally the blue was WAY OUT:
http://www.spydertrips.com/pix/TV/dsc...
now its CLOSER:
Here is the RED convergence, seems OK except for the upper RT:
http://www.spydertrips.com/pix/TV/dsc...
http://www.spydertrips.com/pix/TV/dsc...
But the BLUE only horizontally converges at the center RT of the screen:
http://www.spydertrips.com/pix/TV/dsc...
What would you try NEXT? Replace the OTHER 3 amps (IC702) or perhaps this is a yoke/board adjustment?
Spyder
for some reason this board truncated the URLs. You can do a directory listing of the contents- the GRIDS are the current convergence, the cross is the orignial..
Are these screens from the service menu pages? It looks fairly close to me (and I'm no expert). My Panasonic has tons of adjustments for trapezoid, pincushion, warm, skew, etc.
Are all of the colors at least responding now?
Spyder and CMPalmer, I wish i saw this post earlier. You most certainly can replace these convergence ICs with an inexpensive replacement IC, but my freinds, everytime I have done so in the past, it bit me in the behind. Yes they work, but they do not have the same specifications that the original IC's do and will or might last several months, maybe a year and you will be back where you started from. Also you should replace Both IOC's at the same time, as You will be back replaceing the other one for sure within six months if not sonner. This is also why when you uses the cheap ICs you have to do so much adjustments, and sometimes I would run into a case where I could not get the convergence like it was as spyder stated that he could not get the edges exact. Well my freinds this is why you use the IC's that are recomended. If these are thos STK392-110, that cost 5 bucks, Oh boy, I have seen them knock the entire set dead in the water. Blow out the power supply. I would have replace the 110's with the 150 at least, they will run cooler. Good Luck to both of you.
That's the first I've heard of this. The ICs I bought were an exact part number replacement, just not from a Panasonic parts dealer, and my convergence was nearly perfect as soon as I powered on the set.
As I noted in my article, one of the ICs that I removed did not have proper thermal conductivity with the heat sink which I believe contributed to the failure.
As far as I know, aside from them being from the same supplier, Spyder used an exact replacement as well (except his were the 020's).
If there is enough evidence that the cheaper brand is actually inferior, I will swap them for the more expensive ones. I was under the impression that there were only one or two suppliers for these and no reason to doubt their quality. The difference wasn't that much in price compared to a repair shop.
Thanks for the comments. I may pull the board and go ahead and replace IC702 also.
What do the last 3 digits mean - 010, 020, 150 ? Are they interchangable?
No
these screen shots are from my digital camera of the actual TV. Yes,
all colours are now responding to adjustment, but it seems impossible
to converge it very well. Its not bad at the centre but the edges are
out.
Thanks!
According to the datasheet, they are ratings for different operating frequencies (and I think some voltage differences). Maybe Larry can give us a breakdown on what substitutions are possible.
Ok guys, from my 35 years experience in the feild as well as working on the bench, I have found that the inexpensive, Chinese, 0r Korean replacement parts are inferior to the Japanese types. In some case's the semiconductors dont care, but in some they do as the engineers design the circuits to run at top end, so if you put something with a differant freguency rate, its not going to work the same. This is true with the Audio amps. of today, and thats all this STK is, A tri type analog amp. It as three amps in them as CMPALMER pointed out. I have seen some of these replacement parts cause more damage as they are not manufactured to the strict quality control that the originals are. Now i'm not saying they won't work as they will. For how long? No one can tell. I have seen some of these STKs last one week and you replace it again with a sub. and again two to three weeks its back again. I then would replace with an original, and never seen the set again. I found that as a servicer and for myu good name in the repair field, Just pay for the exact replacements for most parts, not including resistors or capacitors, and you will and are much better off. If I had a bad STK 392-110, and I did'nt have one but had a 150, I would use it, but if I had to order one, I would use the same number.. Now at http://www.partstore.com, you go there and under the part number you type in STK-392, see all the differances in the prices? Thats because these are the ORIGINALS that should be used in the TV's. You may find them less expensive, but it is not a good idea to use one less then 90% of the original as its a known as a counterfit semiconductor, and those are sold world wide every day of the week.
In an audio amp, those numbers at the end of the STK392 is the wattage output for those amps. As I stated before the manufacturers design these things to run wide open so theres very little room for error. Thats why the falure as the overheat and break down.
Thanks for the info. If it wasn't Christmas time I would probably have upgraded my TV, so I don't know if I will pre-emptively replace the ones I put in for manufacturer parts, but if I see any sign of trouble I will do it (and remember to get good ones to start with).
If Spyder's convergence was better and responsive after replacing his, do you think part quality would cause the problems he's seeing?
Thanks again guys for the details. I'll check out parts store, and
perhaps replace these. I certainly respect the vast experience you have
with these repairs. I have almost none! I was sort f proud of being
able to get the IC desoldered and resoldered. IC's are a bear as you
know.
I think I'll replace the other tri-AMP tonight and
see if that improves things. If not I may go the other route and
replace these with hi-quality parts. Larry I would appreciate your
comments on the convergence grid results I showed in my website
http://www.spydertrips.com/pix/TV
It
seems to be center-converged but has severe edge issues! I tried some
board tweaks but the adjustments didn't seem to be enough to bring in
the edges.
I was amazed at the price-difference. That seemed very inexpensive for these parts! Now I guess I see why!
Spyder
OK, the set is better. Tolerable, although I'm not thrilled with the results. The test cross is pretty well converged now:
<br>
<a xhref=ttp://www.spydertrips.com/pix/TV/dscn7353.jpg target=new>BEFORE</a>
and
<br>
<a xhref=ttp://www.spydertrips.com/pix/TV/tvb1.jpg target=new>AFTER</a>
<p>
<hr>
I still have 2 issues that it seems that I can't adjust out. One, I can't seem to get enough BLUE H gain. The pot is maxed out, and you can see
<a xhref=ttp://www.spydertrips.com/pix/TV/tvb3.jpg target=new>HERE</a> and
<a xhref=ttp://www.spydertrips.com/pix/TV/tvb4.jpg target=new>HERE</a>
that it just doesn't quite get there. There is no GREEN H SIZE adjustment, so I can't compensate. I tried all sorts of adjustments, even on the yokes, but I can't converge it very well.
<p>
The other issue is that although the screen <em>appears</em> to be converged, when I toss the GRID up there, the blue is highly non-linear. Converged at the centre and almost converged on the edges, but quite a bout out left of centre. Again, no adjustments seemed to be able to compensate for that.
<p>
Probably, as suggested by readers here, the $20 amps would have been a better choice. But as I'd already bought these I thought I'd give them a go. I checked the board carefully for other failed components. I measured each resistor and they seem to be in spec. I didnt measure the caps but I see no evidence of damage.
<p>
I promise when these go out I'll buy the better ones!
(guess this system doesnt like HTML - edited version:
OK, the set is better. Tolerable, although I'm not thrilled with the results. The test cross is pretty well converged now:
<br>
BEFORE: (dscn7353.jpg)
www.spydertrips.com/pix/TV/dscn7353.jpg
and
AFTER: (tvb1.jpg) www.spydertrips.com/pix/TV/tvb1.jpg
<p>
<hr>
I still have 2 issues that it seems that I can't adjust out. One, I
can't seem to get enough BLUE H gain. The pot is maxed out, and you can
see
www.spydertrips.com/pix/TV/tvb3.jpg and
www.spydertrips.com/pix/TV/tvb4.jpg
that it just doesn't quite get there. There is no GREEN H SIZE
adjustment, so I can't compensate. I tried all sorts of adjustments,
even on the yokes, but I can't converge it very well.
<p>
The other issue is that although the screen
<em>appears</em> to be converged, when I toss the GRID up
there, the blue is highly non-linear. Converged at the centre and
almost converged on the edges, but quite a bout out left of centre.
Again, no adjustments seemed to be able to compensate for that.
<p>
Probably, as suggested by readers here, the $20 amps would have
been a better choice. But as I'd already bought these I thought I'd
give them a go. I checked the board carefully for other failed
components. I measured each resistor and they seem to be in spec. I
didnt measure the caps but I see no evidence of damage.
<p>
I promise when these go out I'll buy the better ones!
Spyder you need a cross hatch on this set to adjust properly man.
OK bro I'll capture the grid- its not pretty!
I'll take the front apart tomorrow..
S
If you do not have a cross hatch generator, use a disc from a DVD to assist in adjusting the grid. You cannot adjust this using a simple cross hair.
I have a grid generator. Here is the image below.
I'm able to get R,G and B Vertical in satisfactorily.
I can also converge R and G horizontal. But no amount of tweaking seems to get B horizontal in. I can't get enough gain to line it up, and since there is no adjustment to reduce G OSIZE, I can't bring that color down to where B is.
Do you suppose I should start tweaking the yokes?
Here is the image in here, http://www.spydertrips.com/pix/TV/
look at :
screen34585.jpg
Sorry if this system messes up the links. It seems to like to do that.
Spyder
Looks like you have a blue bowing problem.. Could just need to be tweeked but also could be the IC's
Yeah I cant adjust it out.. You were probably right about these $5 IC s!
You in Florida man? Wow I used to live in Hollywood. to bad I am so far away now.