Hi there

Riccardo Omage

I’m an Italian  technician  who repairs TV's and other electronic devices. I also write repair cards in Italian,  recently I decided to branch out and translate them into English  for technicians all over the world.
My wife has experience in the technical translation field and she helps me with the translation of these  cards.
My friend Roberto Salerno also co-operates with me by giving  me his repair cards.
These  cards are authentic, taken from our day to day experiences.

> Now we have our first E-book on this subject <
> Our  2nd. E-book on LCD TV's will be completed soon <

If you think that what we have to offer may be of interest or could help you in any way please don’t hesitate to contact me at this E-mail address:

itvrep2@gmail.com

TVC INNO-HIT 21” REPAIR CARD

Roberto Salerno

Brand: Inno-Hit  21”

Model: RF ST TX Silver   chassis 11AK30

Schematic: download from www.electronica-pt.com

Fault: completely dead

Once opened, the first thing I do is measure the voltage presence on the electolytic terminals C809 (150uF-400V), but no voltage results here. The main fuse is not burnt black and gives me a good measurment.
I notice however that the resistor R828 (2,2 ohm-5W) is interrupted.
For sure there is a short circuit somewhere, this reflecting on the fuse and which damaged the limit resistance.
The rectifier bridge, composed of  four separate diodes is Ok, so also for various other components.
I finally find that it is the MosFet Q801 to be in short-circuit between Source and Drain.
On the schematic I see that it should be a 2SK2750, I instead find a P6NK60ZFP assembled.
I decide to fit a 2SK1118 which normally adapts well on these circuits.
Beforehand I try to understand the real cause of the MosFet fault in question.
I check a few things, in particular  the weldings. There is no evident  sign of dry joints however some-thing happens when I stimulate the blue capacitor C811. The rheophore (warm side) found on the welding seems to slightly move. I resolder this welding and others nearby; the new MosFet is already inserted and I replace the R828 resistor (2,2 ohm).

I give power on and the unit remains in standby mode with the red led on. With the remote control I switch on the TV and obtain positive results.
The welding at fault was practically invisible, there were no evident "cold" cracks.
It's important in a case like this to find the real cause of the MosFet shorted.
After a normal test period my repair is complete.