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.

TVC THOMSON 28” REPAIR CARD

Riccardo Omage

Brand: Thomson 28"

Model: 28WX65ES   chassis ICC19

Schematic: download from www.eserviceinfo.com

Fault: stuck in standby

This new client was sent to me by a friend of a friend, he had previously taken the TV to another Technician for repair and was told that it was the "flyback transformer" at fault and it was impossible to find the spare part. I have no faith in a diagnoses done by others (I think it was probably an excuse). As we know even if Thomson is no longer on the market, HR Diemen always have EHT available, the same for other producers of HT transformers. My doubt was that the TV had been ulteriorly damaged. Apart from the fact that it had been inspected by others the original fault seemed to be not one of the easiest.

The TV is blocked on standby, when switched on the red led lights up but with no attempt to switch on.
All voltages exiting the secondary supply section are regular, but the pilot line signal is absent.
As a consequence I doubt that the  microprocessor (or "microcontroller" as Jestine says) is at fault because I have no response from either frontal keys or remote control.
On observation I notice a not original "jumper".
On removal at least the TV makes an attempt to come to life.
The oscilloscope shows me that for a few seconds the pilot line appears on the base of transistor TL001, then also on   pilot transformer pin 1 LL001, but nothing on the base of the final transistor TL030; why is this so?

Explanation:
If cap CL005 is totally open and is not smoothing, nothing passes on the main of the small transformer because the two terminals of the primary spool always have the same potential, there is no signal on the secondary coil.
Needless to say that the replacement of capacitor CL005 cap (470mF-25V) finally resolved the problem, in fact the television restarts to operate normally.

Why the jumper?
My considerations are the following…
Perhaps to put in greater difficulty who would eventually have had to repair the TV? Certain colleagues use the oscilloscope, since going digital it seems to be the most useful instrument for fault finding even if it is more time consuming, others maybe hope for a bit of luck?

In any case, the jumper had been inserted between pins 5 and 6 of the chip IP140 (TDA8139) which operates as a double voltage stabilizer and is found on the secondary supply. Pin 6 is related to the reset function (UP_RES) and goes to the integrated Microcontroller (section R). That is why all functions were blocked. Once the jumper was eliminated the TV was no longer in standby and the pilot line appeared even if only for a few seconds. With the remote control I managed to switch off the front red led, but it then re-activated, at least after this operation I saw that the television gave signs of functioning.
This was followed by a normal repair.

Hi there

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.

For further information or enquiries, don’t hesitate to contact me at this E-mail address: itvrep2@gmail.com

                                                                           Riccardo Omage