Hitachi TV Repair
This TV resides in my parents basement, where I was staying when I started this project. Since I've moved and didn't feel like lugging this monstrosity with me, this project has been put on hold.
My parents have a 31" Hitachi TV made in 1941. The set is in decent condition other than the fact that there are horizontal lines across the top of the picture. It started out small, but has spread to cover a majority of the screen. I've looked into TV repair a little before and it seems like a lot of problems can be solved by simple capacitor replacement. I figured, why not give it a try.
I started, as usual, at Google. Looking for any information I could find on this model of TV.
Google turned up this great post on network54.com Tech Forum. It list the various capacitors that could be the cause of different problems.
- Horizontal lines on left side...... Replace L711 and C735.
- Weave in pix...... Replace IC901
- Vertical bowed..... Replace D752 and D753.
- Pix bowed...... Replace Q752, L711 and C736
- Vertical Foldover...... Replace of course C627 and C625
With this information I began to disassemble the TV in order to replace the suspect capacitors. First thing to do was remove the back panel.
This exposed the electronics to be worked on. The main board sits in a tray attached to the front of the system.In order to get to it to do any work you have to remove a screw on either side.
|Left Mounting Screw||Right Mounting Screw|
With these mounting screws removed the whole tray slides back for easy access to the electronic components.
|Electronics Tray||Electronics Tray Exposed|
With the main board pulled out I was able to find the capacitors C625 and C627, which should be responsible for the vertical foldover problem.
|C625 & C627|
I pulled these caps to find that C627 is 100uF, 35V and C625 is 47uF, 16V. I replaced both of these caps and powered up the TV to discover no improvement was made. Since I believe these caps are related to the vertical alignment my next step will be to examine the circuitry in their vicinity. I'll be looking for any mushroomed or discolored capacitors or ICs...
More to Come?
Enjoy and feel free to report any problems or suggestions to firstname.lastname@example.org.