No High Voltage

Model no. Sony KV-32S25
Symptoms: No Highvoltage

Measuring the voltage across the Horizontal output collector i found that the 140VDC drops to 85VDC upon turning-on. When i check the Horizontal driver transistor Q501 it also fluctuates from 85VDC to 140VDC. I remove the H-Out Transistor, then try starting up the set. After powering-up i check the collector voltage of the horizontal drive transistor, now it's stable and it stays on 85VDC. This gives me an idea of the hold-down circuits. Replacing the Flyback transformer fix the problem.

Dead Set

Model No: Sony KV-32TS46
Symptoms: Dead Set

Remedy: I thoroughly check and inspect the condition of RY602. It is the switching relay which is responsible for turning on and off the TV set. One side of RY602 is connected to power oscillator output that runs nearly 350 VAC peak-to-peak at 90Khz. Once the relay is closed this energy is forwarded across the power output transformer and provides the drive necessary to produce the B+. Measuring the input voltage of the relay with respect to ground i got 150 VDC. On the other side it has 3 VDC. Therefore, RY602 is defective.

Electrical Safety

TVs and computer or video monitors are among the more dangerous of consumer electronic equipment when it comes to servicing. There are two areas which have particularly nasty electrical dangers: the non-isolated line power supply and the CRT high voltage.
Major parts of nearly all modern TVs and many computer monitors are directly connected to the AC line - there is no power transformer to provide the essential barrier for safety and to minimize the risk of equipment damage. In the majority of designs, the live parts of the TV or monitor are limited to the AC input and line filter, degauss circuit, bridge rectifier and main filter capacitors, low voltage regulator, horizontal output transistor and primary side of the flyback transformer, and parts of the startup circuit and standby power supply. The flyback generates most of the other voltages used in the unit and provides an isolation barrier so that the signal circuits are not line connected and safer.
Since a bridge rectifier is generally used in the power supply, both directions of the polarized plug result in dangerous conditions and an isolation transformer really should be used - to protect you, your test equipment, and the TV, from serious damage. Some TVs do not have any isolation barrier whatsoever - the entire chassis is live. These are particularly nasty.
The high voltage to the CRT, while 200 times greater than the line input, is not nearly as dangerous for several reasons. First, it is present in a very limited area of the TV or monitor - from the output of the flyback to the CRT anode via the fat red wire and suction cup connector. If you don't need to remove the mainboard or replace the flyback or CRT, then leave it alone and it should not bite. Furthermore, while the shock from the HV can be quite painful due to the capacitance of the CRT envelope, it is not nearly as likely to be lethal since the current available from the line connected power supply is much greater.

Hitachi Notebook from Japan

This is a small laptop computer from Hitachi with an Intel Celeron 300 processor, 2GB Hard Disk Drive (HDD), and 64MB Ram. You can power-up the machine by pulling the slide power button at the right side, great... the unit showed up Hitachi logo and do some power-on-self-test i also heard the HDD spinning. Fortunately, it's still alive it boots up but there is no Operating System installed. Time to check the disk, too bad... the utility reports a bad sector near the very beginning of the disk or near the track zero - meaning the Drive is unusable. I tell the owner the status of the laptop and told her that we must replace the hard drive to put their pc back to work. But she doesn't want to spend much for it, so i made a decision, i dragged it home with me to see what i could do to fix it.

At home i started to make some debugging on the drive first, then do low-level formatting. After that, i proceed on marking the bad sectors. Even though the drive is only 2GB in size and the damage is on the beginning of the disk, i decided to broke it into two partitions to isolate the good to bad clusters. Formatting the drive is so smooth, now is the time to install an OS hmm... what do you think is the best, i have the following options in my mind - Linux, nope they aren't going to use it for hacking. WindowsXp, well the unit's hardware can't handle that OS. WindowsNT, not ideal for home use. Windows98, the disk is damaged so we should minimize the disk space usage. Windows95.... YES! I guess this one is the best. First, an ease of use and second to minimize workloads for the damaged drive, so i prefer Windows95! As expected, i spent a couple of hours installing windows. But i feel great because it install and run the OS smoothly.

Electronic Repair

All electronics appliances do eventually wear down and will eventually need some repair. From power cable coming loose and wearing out through television parts getting overused and in need of replacement to DVD player lenses getting shaken loose, there are plenty of issues faced by owners of electronics. It is to help with these issues that there are electronic repair shops.
Bring your damaged or unruly electronics into your local electronic repair shop, or even have their repairmen come by to check out whatever electronic gadget that isn't feeling so well. The repairmen will either then and there fix whatever electronic gizmo needs fixing or bring it back to their shop if necessary. Or, if you feel confident, you can buy some spare parts and do the repairs yourself.
Whatever your decision, an electronic repair shop, both those online and the local shops, are open and available to help you with whatever electronic maintenance issues you face. Call up their electronic repair shop experts to ask for advice, or even for a hand, or visit one of the online electronic shops for spare parts and your repairs will be quickly- and well-done and your electronics will once again be good-as-new.