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TV Servicing Tips
This page provides TV servicing information for use by qualified TV service engineers to carry out set up and alignment tasks.
Use these tools and procedures entirely at your own risk. TV sets contain many hazardous (and potentially lethal) voltages. You should never remove the back cover of a TV unless qualified to do so.
Disclaimer
I will not be held responsible if you damage your TV or suffer personal injury as a result of using the information contained in this article. If you're not technically qualified or knowledgeable, you should leave these TV servicing procedures well alone and get advice from a qualified TV engineer or send your set to Toshiba for servicing.
4:3 TV Testcard Downloads
Click the thumbnail images (left) to download Colour Testcard F and Testcard G as digitally re-mastered high resolution JPEG images.
These can then be uploaded onto your Mobile Phone, I-pod or Camcorder memory stick and viewed through your TV's auxiliary AV input to assist with the alignment of convergence, focus and geometry. This technique allows TV or monitor alignment without the need for an expensive TV testcard generator. Our test card images can also be used to align widescreen 16:9 TV's when viewed in WIDE mode.
These testcards may not be copied or re-distributed elsewhere on the web without the prior written consent of KSL Consulting. We use advanced anti-copying technology to identify and deal with online plagiarism.
Link To Us
Found our testcard download useful? Please link to this page from your blog or website. Simply copy this HTML into your website to add a text link:
<a href="http://www.stevelarkins.freeuk.com/tvtools.htm" target="_blank">TV servicing tips & testcard download</a> - Dowloadable high resolution TV test pattern / testcard from the KSL Technical.
Acknowledgement
We are grateful to Telefusion Southend for preparing our downloadable TV testcards.
Toshiba TV Servicing
I have received numerous e-mail requests for a summary document defining the service menu options present on the Toshiba widescreen TV and how they can be used to correct picture geometry issues.
This article is written to answer these requests and to save me time dealing with each e-mail directly. Many Toshiba TV's don't seem that well set up when they leave the factory.
My Toshiba 36ZP38 CRT TV suffered from bad convergence, poor geometry and white tone consistency. Fortunately, I have now resolved these issues and I'll help you do the same in the articles below.
Recommended TV Settings for the Toshiba CRT TV
Before you jump to conclusions about your Toshiba TV needing servicing set it up as follows to see if the picture improves:-
- Contrast - The set may comewith Contrast set to 100. This is FAR too high and causes picture de-focus and screen colour blotches. Set contrast to 65 maximum. Try settings between 60 and 65%.
- Brightness - Tests with a grey scale test card on my Toshiba TV showed the correct setting to be between 58 and 62. 62 for a bright room; 59 for a darker night time environment.
- Sharpness - Set this to your own preference. if you are seeing digital TV artefacts reduce the sharpness to mask these accordingly.
- Black Stretch - This Toshiba TV option always tries to create black on the darkest points of the picture, even if real black level is not reached in the programme material. I have tried both ON and OFF and prefer to leave it ON which is the default setting. If the picture always looks too dark to you even after setting brightness to 58 then turn this option OFF. Some DVD's can look dark with Black Stretch 'ON'.
- Picture Mode - I use NATURAL mode (default setting) although it can be a little jerky on fast moving objects. ACTIVE might give better results for fast moving sports games etc. See the Toshiba TV manual for more about each mode.
- Noise Reduction - I leave DNR on (default setting). This cleans up noisy aerial signals. I must say though that analogue aerial-derived TV pictures look quite poor on some Toshiba TV's compared with RGB or Component DVD or satellite images. DVD in particular, through the Component video inputs looks fantastic. If you haven't got UK Freeview or Digital Satellite and you own a Toshiba widescreen TV, you don't know what you are missing! You're missing true 16:9 viewing for one, without the always cut off top/bottom 14:9 letterbox images on nearly all channels these days!
Toshiba Widescreen TV Service Menu Access
No service menu option on this or any other TV should be changed unless you are qualified to do so or you may render the TV useless or damage it irreparably. In all cases, even if you are qualified to make adjustments, nothing should be changed without first noting all factory service menu settings.
Service Menu Access Procedure
To access the Toshiba service menu, press and hold the handset sound mute button whilst pressing the TV's front panel 'Menu' button (under the front panel cover on the TV). The up/down channel buttons on the handset step through the options and the left/right buttons change the data values. Turn the TV off to get out of service mode and DO NOT touch any other handset buttons whilst in service mode. Service menu access is also similar for many other Toshiba large-screen TV's so this procedure may work on other Toshiba TV's - even those sold outside the UK.
Click here for a list of each widescreen Toshiba TV Service Menu adjustment with details on the purpose of each.
The factory settings of each service menu option will be entirely different on every TV manufactured, due to component, tube and scan coil tolerances, so don't under any circumstances adjust your TV's settings to my factory default settings or your TV's picture will probably look awful! The factory settings are provided out of interest - the useful part of this document is actually the definition of each service menu option. You will see that some geometry settings are duplicated for each screen mode such as 'Cinema' and 'Subtitle'. This could, for example, help resolve a geometry problem that's present just in one screen mode.
Geometry Problems - Horizontal Curvature
Many of the problems described by owners of the Toshiba 36ZP38 TV relate to curvature of horizontal lines which are not straight (dipping down in the middle of the screen or rising up at the screen edges). Unfortunately, the service menu options will not correct these geometry flaws and there is very little that you will be able to do to correct them short of changing the tube and/or scan coil assemblies and this is a massive and incredibly expensive undertaking. If you can't live with your set's horizontal curvature, then negotiate an exchange set early on after purchase and hope that one is better or buy a Plasma which should be perfect in terms of screen geometry!
It is normal for horizontal lines on large screen tube TV's to bow or have upward or downward flaws of a few millimetres from 'true' horizontal. My Toshiba TV has a small rise in horizontal lines at the screen edges but luckily no real bow in the middle anywhere.
Geometry Problems - Vertical Curvature and Distortion
Curvature of vertical lines on Toshiba TV's is much easier to deal with and can be largely corrected by the service menu options.
NOTE EVERY FACTORY SETTING BEFORE CHANGING ANY OF THE SERVICE MENU ITEMS.
Use the UP/DOWN handset buttons to view each service menu option in turn and never alter the RGB colour drive or RGB Cut-Off settings as these need professional colour temperature equipment at the factory to reset.
Always use a test card provided on this page and let the TV warm up for at least 15 minutes before altering any service menu setting. When you adjust vertical curvature don't just look in one part of the screen - look at all vertical lines up to a third of the way into the picture, averaging out any geometry errors and minimising them. You may have to reach a compromise setting that bows the vertical lines very slightly outward at the very sides of the screen a little in order to get the vertical lines further into the display vertical.
If you've got vertical in WIDE look at the other screen modes such as 4:3 and 14:9 modes which should have straight black bars down each side. From memory, I think the settings in WIDE screen mode also affect 14:9 and 4:3. However, Subtitle and Cinema modes have their own (different settings) of these options that can be adjusted separately after selecting these other display modes.
As a general guide the service menu options you may need for Vertical curvature issue correction are:-
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TV Servicing - Screen Convergence
Setting Static Convergence
Convergence errors show themselves as coloured fringes around objects or white lines. On a large screen TV, it is normal to see some convergence errors around the screen corners in particular. The convergence in the centre of the screen, should however, be near perfect as this is adjustable using the static convergence ring magnets on the tube. Look at the test card white cross point at the very centre of the screen (after the tube has fully warmed up) and see if there are any red, blue or green fringes around the white lines in the screen centre. If there are, then the Static Convergence of the tube is out of alignment. If convergence errors are visible from viewing distance, then it may be worth getting them compensated for by an engineer.
Correct convergence is critical to the picture quality of the TV and adjusting it is difficult. It also involves serious risk of electric shock or death as adjustments have to be done with the TV switched on and back cover removed. In short, leave convergence well alone and if you need to, get a qualified engineer to make any adjustments as this procedure is beyond the scope of this document. My advice is not to remove the back cover of your TV unless you know what you're doing. If you get an engineer to adjust the convergence, always make sure that you run the TV for at least an hour before adjusting convergence.
Static Convergence adjustments are made to the pairs of magnets on the neck of the tube after unclamping them. One pair of magnets does the screen purity (nearest the screen face) and the other two pairs adjust the static convergence. The middle magnet pair do red/blue convergence and the pair nearest the back of the tube adjust the green convergence. Moving both magnets together as a pair one way or another adjusts one convergence aspect and moving one of them (only) with respect to the other another adjusts the other aspect.
Setting Dynamic Convergence
Dynamic convergence affects the convergence near the screen edges and corners. It is set by a number of small stick on Perm-Alloy assemblies on the tube neck. These look like plastic strips extending from their stuck on point on the tube's neck protruding under the scan coil assembly. These are positioned during manufacture and should not need much (if any) adjustment unless the static convergence has been altered considerably.
TV Servicing - White Tone Raster Consistency
Poor TV Screen Purity
Poor purity might cause either poor white tone consistency across the screen or it may only be noticeable on totally red, green or blue screens where different coloured blotches appear in certain parts of the screen.
Poor white tone consistency in particular seems to be a fairly common problem on large screen Toshiba CRT TV's. To minimise outside magnetic influences which can make the problem worse, always keep sources of magnetic fields like un-magnetically screened HiFi speakers and the like away from your TV by at least 1.5 metres. Only Magnetically screened speakers like the ones Toshiba supply as part of the surround sound system, may be placed directly under the TV screen on a cabinet shelf on on top of the TV.
Even abiding by these rules, screen blotches on all-white screens can often be a problem on large widescreen TV's and Toshiba seem to be aware of the issue. Various people have told me that Toshiba say such problems are "normal" and "to be expected". To minimise this problem YOU CAN HELP by always keeping the contrast setting of the TV below 70% and brightness preferably below 60%. This improves the picture enormously too in terms of improving picture detail.
Screen corner blotches are corrected using small stick on 'bow tie' magnets on the tube back. Toshiba should be able to supply purity correction magnets such as these to a professional service engineer to try to correct any serious screen corner white tone consistency problems you may have. The 'bow tie' purity magnet is moved around the screen back with the TV switched on until the white tone consistency is optimised in the affected area, then the magnet is stuck on the tube.
A serious risk of electric shock or death is always present when working on TV's with the cover removed. Do not attempt such adjustments yourself. Leave this to a professional qualified TV engineer!
TV Grey Scale Adjustment
If your CRT TV has developed a green tint, or the grey scale is green tinged visit our TV grey scale adjustment page for help. Download our free grey scale test pattern to help with CRT TV grey scale tracking adjustments.
Poor Focus on Widescreen TV's
Large screen CRT TV's (particularly 36 inch 16:9 widescreen models) can have inherently poor focus in certain parts of the screen particularly in the screen corners. This is due to the inherent difficulty in correcting the focal distances of the CRT beam between screen centre and extreme screen corners. Before considering any internal adjustment if you are seeing poor focus, bear in mind that turning down TV contrast can significantly improve screen focus with some makes of tube. Overdriving a tube can actually cause poor focus and screen purity by distorting the shadow mask due to excessive beam current. It's always worth checking and assessing lower contrast settings on your CRT TV before altering the focus control of the set. The focus of any TV is accurately set at the factory and unless components have aged or altered in value (or the tube has been replaced) it should not need further adjustment or periodic servicing.
Many high quality more recent TV tubes incorporate clever internal mechanisms to assist in improving focus, but even with the best tube designs the optimal focus for the screen corners may well be different to the optimal focus at screen centre when adjusting the Focus control (usually mounted on the Line Output Transformer - LOPT in most sets). To find the LOPT, follow the tube anode cable back to the LOPT from the rear face of the tube without touching it. The tube anode cable has a large suction cap on it and is mounted on the tube back. Don't be tempted to take this cap off or to interfere with it, as serious shock or even death could result. The tube can also keep it's charge long after the power has been turned off. Always use a fully insulated screw driver when adjusting TV focus. The TV tube focus voltage of most sets is a potentially lethal 5000 volts although in most cases the focus adjustment is a plastic insulated screw on the LOPT.
If lowering contrast doesn't improve your TV focus, my advice is to download the test card from this page and adjust focus at the screen centre to get the white cross hatch pattern as sharply focussed as possible in the centre part of the screen, with the TV contrast set to 75% - 80%. If very poor focus is then present in other part/s of the screen and particularly at the screen corners, you can slightly compensate by reaching a compromise setting of the focus control. When completed, always check for sharp focus in the screen centre as this is the most crucial screen area!
Servicing Panasonic TV and Video Tuners
The tuner in my Panasonic NVHD660 video failed recently - no stations could be received and the video's clock continually flashed 0:00, as it couldn't get the Teletext data to automatically set itself. To get at the tuner involves taking virtually every circuit board out of the video, the front panel assembly off and the chassis out.
I have replaced many Panasonic video and TV tuners over the years as they don't seem very reliable. Replacement tuners can be obtained from Nedis Ltd formally SEME Ltd, but they're not cheap. CHS Interactive and Wiltsgrove seem to offer more competitive prices. This time, I took the video chassis out and re-soldered all the earth points inside the faulty tuner can, with a hot soldering iron bit. I then carefully re-soldered any dry joints (dull grey looking solder joints (rather than shiny looking) with an ultra fine soldering iron bit and put it all back together. This completely fixed the fault. It therefore seems that, with some knowledge and care, you can save on your TV servicing bill by repairing Panasonic TV tuners yourself.
Other TV Servicing Articles
Repair FAQ offers some very useful TV servicing articles covering generic TV alignment. The site deals with a wide range of topics from convergence adjustment to correcting purity problems.
Further Advice and Help
If you found the TV servicing tips on this page useful, please link to us from your own web site or blog.
Unfortunately, we have cannot answer TV servicing questions or queries relating to TV faults on a specific TV make, model or chassis. This page should answer the most common Widescreen TV servicing problems as it provides generic TV troubleshooting tips. If you feel information is missing or inaccurate, please to help improve this page.
