This BenQ T705 Liquid crystal display Watch consists of a well known fault of show shutdown right after several your self “Upon” for handful of seconds. The induce of the condition was historically a shorted just one or 2 of the C5707 force pull transistors. In addition to the shorted transistor, just one much too incorporates toward examine the tuning capacitor for higher ESR cost with the aid of ESR meter. If yourself do not individual one particular, your self can seek the services of the electronic capacitance meter towards test the capacitance well worth. On the other hand, in opposition to my expertise, examining just the capacitance charge doesn’t ensure that the capacitor is optimistic except if oneself establish it with ESR meter. The motive why I target upon examining this tuning capacitors was considering the fact that the capacitors incorporate a significant failure price tag that may possibly trigger the C5707 transistor in direction of transfer shorted. By yourself way too comprise toward adhere to the substantial voltage transformer pins thoroughly. I experienced arrive throughout fairly a amount of shorted C5707 transistors brought on by means of dry joints within pins of the substantial voltage transformer.
Inside this scenario, as ordinary the moment I contain established that just 2 C5707 transistors shorted, I started in the direction of try out the tuning capacitors and keep track of the pins of the significant voltage transformer. Both equally the tuning capacitors found out in the direction of be ok however there were being dry joints inside the transformer pins. Contemporary solder was used towards the superior voltage transformer pins and I’m well prepared towards “Upon” the Liquid crystal display Keep an eye on. Wager what? The Check consists of the identical symptom once again which is demonstrate shutdown right after number of seconds! I have on’t imagine it as optimum of the period it will definitely do the job as this is a well known fault!
I started out in direction of recheck the bordering aspects that incorporate romantic relationship toward the C5707 transistors however identified no errors inside it. Deciding the board innumerable moments didn’t make clear any wrong soldering process. There really should be anything at all that includes long gone improper that experienced brought on the Liquid crystal display Keep an eye on toward shutdown. Deep inside of my center I have on’t suspect backlights situation simply because the C5707 transistors shorted was induced by way of dry joints in just the large voltage transformer. Beside, the backlights were being pretty trustworthy for this BenQ Liquid crystal display Observe design.
Wondering again, I acquired a refreshing badge of C5707 transistors against my digital makers not lengthy back. The heart pin (leg) is a little bit short than the other 2 as listed versus the picture listed here. I strategy toward myself would it be this badge of transistors that incorporate dilemma leading to the exhibit shutdown soon after handful of seconds? Of class I can’t blindly suspect the transistors until I consist of some evidence of it. The discovering starts………………
Screening the C5707 transistor with an analogue meter established in the direction of X 1 and toward X 10 K Ohm doesn’t seem to be which include it contains predicament. Evaluating the end result with an initial C5707 transistor did include some variation inside the X 10 K Ohm variety however the looking through is affordable versus my yrs of practical experience inside of tests transistor. The simply just factor that I haven’t in comparison is the Hfe studying. I made use of the famed Top Atlas variables analyzer towards review possibly transistors and I could possibly obviously perspective the significant change in between the Hfe readings of the 2 transistors. The primary C5707 transistor includes Hfe really worth of 379 whilst the refreshing badge of the C5707 transistor includes Hfe charge of 161! At past I identified the solution!
I did experimented with switch the 4 C5707 transistors at 1 move with the clean badge of transistors nevertheless the outcome was the identical. Putting in the transistors that include the Hfe studying of 350 towards 400 resolved the clearly show shutdown situation. This circuit overall look together with it can merely energy with the identical style of transistor that contains the Very same Check our website Hfe cost! That’s why for this style of Watch circuit, lots of professionals scarcely can obtain a relevant substitution. Within just other words and phrases, even if by yourself may possibly consider the kim kardashian hollywood cheat alternative transistor that incorporate large Volt, Amp and Watt still alternative Hfe really worth, yourself nonetheless received’t be ready toward provide the Liquid crystal display Watch back again toward existence back. Versus the earlier mentioned try out, this Observe circuit is made up of voice out loud and apparent that it basically have to have the exact component quantity with the exact Hfe really worth until yourself incorporate some equivalent transistor alternative specification that is related toward the unique a person.
For my guests that are in just this digital fixing line, while some of by yourself may well not be inside of the Liquid crystal display Observe fix, I be expecting on your own will take up this content material and employ it within just your marketplace. Who appreciates just one working day yourself would contain deal with the similar circumstance that I’m struggling with and this short article might smoothly assistance your self toward address your predicament immediate. Comprise a very good and a fortunate working day!
