Improving HV regulation

[lnx64]

I know this may end up just being a lost cause, and not that big of a deal, but I want to experiment a little just to see if it can be done.

When watching movies on my 80's Samsung (I can't get the model right now but I can get the chassis number if you want, the back simply has no model number for some reason, but I would have to take it apart first), any bright flashing of course changes the picture size a little due to poor HV regulation. Can this kind of thing be improved or is it down to just a cheap design and would require far too much work to improve?

[zeno]

Your set probably uses an STR regulator . Lets use an STR 30130
as example. The 130 means it is a 130 volt regulator. ( the also come
in 30123, 30125, 30135. etc).
Near the STR there is a BIG resistor. One side is apx 150 VDC the other is 130 VDC. That voltage should stay the sam from no raster to full brightness.
Now if you have a Variac hang you meter on the 130 V end of resistor
& run the set from 100 VAC to 135 VAC It should be a constant 130 V.
If either tests fail you MAY have a power supply problem.

Nature of the beast is also possable. Low price sets have simpler designs,
are a generation or 2 behind, & overall quality is lower than the
higher end sets. Thats why some sets can get NTSC stations on
rabbit ears up to an easy 150 miles & others wont see it at all.


73 Zeno
LFOD !

[lnx64]

Originally Posted by zeno

Your set probably uses an STR regulator . Lets use an STR 30130
as example. The 130 means it is a 130 volt regulator. ( the also come
in 30123, 30125, 30135. etc).
Near the STR there is a BIG resistor. One side is apx 150 VDC the other is 130 VDC. That voltage should stay the sam from no raster to full brightness.
Now if you have a Variac hang you meter on the 130 V end of resistor
& run the set from 100 VAC to 135 VAC It should be a constant 130 V.
If either tests fail you MAY have a power supply problem.

Nature of the beast is also possable. Low price sets have simpler designs,
are a generation or 2 behind, & overall quality is lower than the
higher end sets. Thats why some sets can get NTSC stations on
rabbit ears up to an easy 150 miles & others wont see it at all.


73 Zeno
LFOD !

Yea this isn't quite a high end set: https://i.imgur.com/7kb419z.jpg

Though it does have some elements of being high end, for one the HOT is huge, and not at all small like most others I've seen from this era, and the speaker is on an isolation transformer, allowing me to install that headphones socket on the side safely without risk of electrocution from a hot chassis (the rest of it is hot however).

I'll see what I can do, but I'm fairly confident this is from the design, as this TV has always done this, even when I replaced the flyback as the original turned into a fireworks show (HR Diemen is what I used, however it's spelt).

I did modify the vertical on it however, and it actually helped. Since I'm using a Roku 4k on it through an HDMI converter, it doesn't offer 4:3 whatsoever and only 16:9, so I adjusted the v-size to be smaller so it's 16:9 now permanently, and it tends to do this less and actually hold better.