Samsung 23 inch CRT monitor destructive dissasembly. - Page 1
Forum section: electronics / general

author: SeanB
author_rank: Super Contributor
timestamp: October 07, 2012, 01:36:01 pm
content: Had this old CRT monitor finally die, power on, give video and nada, standby light goes green out of powersave, relays click inside to select inputs and heaters are alight but nothing doing on the screen. Looks like the LOPT finally died, no HT crackle from it starting up. 15 years old, made in 1997 and pretty much on all the time since then.Took this boat anchor off the desk ( it is around 40kg) and replaced with another CRT, 19 inch this time ( and had to drop the resolution to 800 by 600 as the user moaned about the writing being too small at 1024x768, even though the monitor will do 1600 by 800 no problem) that is not so dead, and left it for later.Finally got tired of kicking it, and decided it was going to become 3 piles. Take the back off, and it is very solidly screened, and had multiple screws holding the assorted screens together, at the end I had around 100 self tappers in a pile.Back panel is the video inputs, both VGA and RGBHV, along with a non used audio input. The PCB has all the video switching and the drivers for the cathodes there, all on heatsinks that still have sticky heatsink compound even after being toasted for 15 years. All through hole construction and a full ground plane on the top of the board. The Samwha caps are still perfect.The main board is rather dense, and a little dusty with black dust all over, and crammed with wiring looms.On the bottom is the variable capacitor for the LOPT tuning, all switched by the bare TO220 transistors under them. Note the black thick dust on the LOPT at the top .6 caps and 4 switches, along with the discrete driver circuits as well.The main microcontroller, this is a 8052 derivative with onboard ROM, it does housekeeping and switching only, no video processing really aside from providing a basic OSD to the screen. The 9 pin power device is the vertical driver, all stuck there in the corner with IC302 driving it.Input side, note the multiple filters and mains suppression capacitors, along with the degauss circuit with it's control relay Ceramic fuse as well, and the main reservoir caps are not bulged, just the plastic top cover is domed, under is flat.CRT base, in later versions all the video circuitry landed up here in 1 IC, but this has only really connections and flashover protection components, along with a lot of ground leads for the CRT Note A2 ( thick red lead top left) has flashed over a few times in it's life, the burn is visible on the plastic, and probably was a contributor to the LOPT frying. The big power resistors are for the heaters, as they normally are 6.3V, but are generally run from a higher rail.Bottom of board, all nicely silkscreened and no bodge wires in sight. Screwed to the steel frame, not soldered like later ones were.One very dusty LOPT, and the big line driver transistor and a very undersized for the mount efficiency diode. Looks like they underestimated the dissipation of these 2 devices, note the extra heatsink stuck on top of the existing frame, with 2 screws and thermal paste to hold and transfer heat. These 2 components probably dissipate 30W between them, and this aluminium frame is the same in all monitors across the range from 14 inch up.Deflection yoke assembly, a little more than 2 coils....... Has a board to provide temperature compensation, current compensation and linearity compensation, has about 2kg of copper wire in it, and the same again in ferrite. note all the magnets to provide fixed compensation, and the silicone glueing it to the CRT back.Front panel controls, a lot of pushbuttons and a nice encoder, along with 2 pots for brightness and contrast, along with on the right the board from the yoke that did pincusion correction for the CRT, it fitted on the gun and did something.....Now in 3 piles. One load of plastic went to the wheelie bin, the steel is in the scrap pile, there is about 4kg of it. One CRT safed, and will be dropped off at the Ewaste bin to go to OHL land......The boards will be in my pile of used spares to fix dead electronics. Cheaper to look for an odd resistor or capacitor than to buy a new one, especially for quick and cheap repairs. Heatsinks are useful too, along with diodes.

author: Frangible
author_rank: Regular Contributor
timestamp: October 07, 2012, 04:37:13 pm
content: That's a true dinosaur - I can't see any SMD components!

author: SeanB
author_rank: Super Contributor
timestamp: October 07, 2012, 05:17:00 pm
content: It is older than some members of this forum...... Made in 1997, when Samsung actually did make them to last. At the time it was one of the most expensive monitors around in the market. Remember the competition was a 13 inch or 14 inch monitor, this was double the area, and crisp and focussed in all corners, with near perfect linearity. A circle was a circle no matter where it was displayed on the screen.

author: Amarbir[Lynx-India]
author_rank: Frequent Contributor
timestamp: October 07, 2012, 05:35:32 pm
content: Quote from: SeanB on October 07, 2012, 05:17:00 pmSean ,Whats the model No of This ?

author: SeanB
author_rank: Super Contributor
timestamp: October 07, 2012, 05:49:51 pm
content: Cannot recall, it was not something i noted, just that it was a Samsung Syncmaster 24 inch monster. I was more worried about dropping it on my feet than worrying about the model number of what was destined to become a conversion.

author: SeanB
author_rank: Super Contributor
timestamp: October 24, 2012, 12:07:21 pm
content: Went and measured the capacitance of the CRT. 1.882nF. No wonder these never suffered from breathing at full brightness.