Question about Toshiba 55H70 55" Rear Projection Television
I found the screen where you line up the yellow, red and blue crosses. Am I supposed to get them all on top of one another? Some of them don't want to move, is that a problem?
Today, I started researching the exact same problem on the same model TV. From what I've learned, it seems this model TV (and many others with this part) suffers from a part that runs hot and is not very reliable. The part so frequently goes bad, that one person on the forums bought the parts for "when" not if it goes bad. So, you are far from alone.
The failing part apparently responsible for the color convergence problem you are experiencing is the STK392-110. There are two of them in your TV and together they control the color convergence of the 55H70. Basically, these 2 ICs need to be replaced with the newer and more reliable replacements, the STK394-160 (alternatively, you can also use the STK392-150 or STK329-180, but the STK394-160 is the latest and greatest equivalent for the original part). It is best not to replace the STK392-110 with another STK392-110 (which is what many repair shops will do).
To perform the replacment, you have 2 choices:
1. Hire out a repair at $400-$700. However, often TV breaks again with same problem in less than 6 months because many TV repairman replace only the bad ICs but not the "feeder" parts (i.e. resistors) so these bad feeder parts fry the new ICs also in one week to 3 months. If you hire it repaired, make sure the repairmen has checked the resistors around the IC to ensure they are within tolerance. Also, the repairmen should use thermal compound to reseat the ICs back to the heatsinks. Otherwise the repair won't last.
2. Fix it yourself for under $60. The process can be tricky, but if you are slightly technically inclined and know how to use a soldering iron, you can fix it yourself with less risk of it breaking shortly after.
IMO, option #1 doesn't make sense for a TV that is over 4 years old. That's just too much good money after bad. If option #2 is not feasible, personally, I'd rather put the $400 to $700 or more toward a newer model.
However, if the thought of holding a soldering iron doesn't intimidate you, then option #2 can make a great TV _better_ than new. So, assuming you choose to fix it yourself, this is what you'll need to do (AFAIK). First of all, make sure you only get Sanyo original parts (lots of Chinese knock-offs that don't last). The original STK394-160 is best purchased from a reputable Hitachi licensed dealer (Hitachi apparently makes the 55H70 and Toshiba puts in name on it). B&D, acme-sales, vance, tritronics are all good choices to buy reliable, Sanyo parts from. The STK394-160 is newer and harder to find. Best way to obtain this part if via the Hitachi kit part number X480293. I just purchased the part number X480293 , which I just purchased from Tritronics for $37 + $9 shipping at:
This repair kit includes 2 STK394-160 ICs. Both will need to be replaced (even if only one is bad). This kit includes both ICs, plus some extra resistors. While the ICs are used in many TVs, the resistors have Ohm values that are specific to each TV. So, the resistors in the kit will likely be of no use to you on the 55H70. Still, it is a good idea to test all the resistors in your TV (R7711, R7721,
R7116, R7726, R7736, and R7731. are MF, 1.2 ohm, 2W resistors according to service manual) with a meter and make sure they are still reading the manufacturer values they are suppose to. If their resistance has changed from original specs, they will likely destroy the new ICs. Look for bad solder joints and resistors that test bad or look fried and replace and resolder. Pull the old STK392-110 ICs and replace with the new STK394-160 ICs. Be very careful while inspecting those solder joints and resistors because missing even one minor problem can prevent success. Also, remember to use the thermal compound to reseat the ICs against the heatsinks.
If this doesn't work and you have checked all the resistors and solder joints, the convergence yoke may also have problems. But cross that bridge when/if you come to it.
Some useful links with more instruction and pictures on how to do this replacement:
Note: I'm no expert and basically in the same boat as you. Just sharing what I've learned. So, any experts, please let me know if I missed or incorrectly stated anything.
Posted on Dec 21, 2008
Is there an advanced convergence setup anywhere in the menu where the screen displays a grid? If so, you might want to get into that and move along the grid to each section that looks off. Adjust until the color falls behind the gridline, and move on to the next. It can be a time-consuming process, but should take care of your convergence issues.
Posted on Jan 20, 2009
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