Ajusting H-Liniarity on a monochrome TV?
Hi all, My 1970's CRT TV has some horizontal linearity issues, The picture is wider on the left and more squashed the further to the right of the screen. The TV is compeletely solid state, No valves inside. There's a dial on the back of the unit which says V-Lin and i all ready got it perfect but there's no H-Lin. There's Horiz-Hold, ACC, Height and V-Lin which can be turned with a screwdriver from outside of the case. None of the internal dials are labelled and I'm worried I could damage the set if I adjust them. There are also some tall aluminium cuboid shaped things that have a hole in the top with an Alan key hole inside.
If anyone has any suggestions i would be glad to hear it.
Thanks to anyone who can help.
- FredLv 78 months ago
Many of these type of faults in those old CRT tvs are caused by old electrolytic capacitors that need replacing. You have done well if it has worked all these years and not needed some electrolytic capacitors changed. I am unsure if many of the younger TV technicians could even work on an old analogue B&W tv these days and you may have to try and track down an older technician. Likely he will say a set that age is not worth fixing but if it has sentimental attachment for you then if the picture was clear before maybe it is worth finding a guy who can fix it. Many TV techs if they do not want to fix the set will tell you it cant be fixed or you can't get parts anymore because they do not want to admit they can't fix it as the technology was analogue which they are not taught anymore. Search around for a guy who knows how to fix the old stuff as I am sure it is repairable.
I know this stuff because I used to be a TV tech back in the analogue days.
- spacemissingLv 78 months ago
Few TVs have a horizontal linearity control,
so don't be disappointed if there isn't one on your unit.
The most likely reason for the problem is aging capacitors.
Carbon resistors change value as they age, so they can be troublesome, too.
Another possibility is that the deflection yoke has shifted position.
In a B&W set, that isn't a big problem to correct,
but in a colour TV it is best left to an experienced professional.
Get a Sams Photofact that covers your model and see what parts look likely to be bad.
Whatever else you do, DON'T ADJUST THE SLUGS IN THOSE CANS!
More radios and TVs have been f**ked up by people messing about with IF transformers
than by any other common means.
If they Do need adjustment, pass the job to someone who knows how.
ONLY plastic and fiberglass tuning tools should be used.
Metal tools will seriously interfere with the function of the transformers.
- Robert JLv 78 months ago
At that age, it's most likely that some of the electrolytic capacitors are aging and failing.
That often causes scan problems (among other things) with older CRT TVs and monitors.
The only cure for those is replace the capacitors.
For info, the aluminium things are screening cans for tuned circuits. Do not mess with those with knowing exactly what each does and having full test equipment to align the RF circuitry.
In other words, don't touch them...
Edit re. you comment:
Any decent electronic component supplier should have them. CPC, Mouser, Digikey, Farnell, RS etc.
Look for the same capacitance (uF) and the same or slightly higher voltage rating.
You will usually find a lot of different versions.
Pick one that is rated for 105'C and with a ripple current in the higher part of the available range and/or a lower series resistance (ESR) from what you can find.
eg. For a 10uF 400V, a value which could be in a CRT TV:
Selecting 105'C temperature rating (or higher) and, say, the top quarter of the ripple current range cuts the selection from almost 60 to less than 20.
You could select the ones with the longest lifetime rating as well if you wish; that cuts it to less than 10 - and many in that range are duplicates, small or large packs.
Any would be OK as long as they physically fit.
Newer caps are often smaller than '80s ones. Check any you select to make sure they are compatible.
If the lead spacing on the new one would be too small to fit the PCB, try selecting a higher voltage rated type of the same value; they should have larger lead spacing.
- Spock (rhp)Lv 78 months ago
make and model number? see back label. then consult owner's manual which you will find online
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- STEVEN FLv 78 months ago
There was NO SUCH THING as a 100% solid state TV in the 1970s and there CANNOT be a solid state CRT.
The CATHODE RAY TUBE, by definition isn't solid state.
Based on your description of the issue, the problem isn't an adjustment. The display itself is failing due to age.
The USEFUL suggestion is admitting the TV was never intended to last more than 40 years.