Orion 32BUA T7609 - 32" CRT TV repair / restoration  - Page 1
Forum section: electronics / repair

author: joebal
author_rank: Contributor
timestamp: July 09, 2019, 01:56:57 pm
content: Good evening all,I couldn't find a specific introduction forum/section, so I'll throw out a quick one here, I'm Joe, 40 years old, lifelong electronics enthusiast. Have no problems wielding a soldering iron, getting around schematics, building circuits, rudimentary repairs etc. However I have close to no true diagnostic ability - I fall short there.After going through three 32" CRT TV's in recent months (and inspecting several others), I've found and purchased one that I would like to settle on, however it needs a little loving care. I enjoy the somewhat niche genre of light-gun games, so I'm fairly restricted with the types of CRT (especially large screen) TV's that I can use.To explain at the limits of my understanding, the screen deflection circuitry must run at 15.7khz for the guns to work. I cannot use 100Hz televisions (which is the majority of the 32" TV's on the second hand market) as they scan at 31.5khz. As these televisions are far and few between, this is actually the only one I have found with a curved tube, which has much better geometry than the flat ones I've had in recent times. For this reason, I decided to try and put some love and care into getting this one up to standard.The model is an Orion 32BUA T7609 - Standard definition, 32", 16:9 aspect ratio, with 2 x SCART connectors.The picture is quite decent, with a couple of minor issues, I've shot a small video:Symptoms:1) I noticed that for the first 10 seconds as the TV starts up, there are faint horizontal retrace lines with a blue-ish screen color - but they immediately disappear after that time.2) When playing a gun game, the screen flickers bright white, once per pull of the trigger (this is by design of the game, in order for the light-gun to register the location of the shot, here is an example from youtubehowever the CRT takes about a quarter of a second to recover properly after each shot, as the brightness decreases for a brief instant immediately following the shot/flicker.3) Small vertical line one the left of the frame, running in 4:3 mode. (Picture in general happens to be about 0.5" to the left.)I was initially going to go for the cowboy approach of recapping and re-resistoring, but I've read some posts talking about that being a potentially harmful endeavour, as some capacitors for example are special/rare. I've also read posts indicating that going straight to the service menu and tweaking around is also not a smart idea, that it is better to try and address the faults instead.I've been unable to glean any information from official materials as I cannot find a service manual - and information on this unit appears to be rare/non-existent.So I'd like to throw this project out to some advice from experienced folks who might offer some wisdom on what the best way to approach a project of this kind would be.Alongside repair, I wonder about the feasibility of improving the classic blooming issues with bright-dark scene changes that affect screen size. From what I've read this is due to poor HV regulation? In the passing of years since manufacture, have any specific components improved that can simply be "dropped in place" to improve this area of performance?I've seen talk that devices (and their ensuing geometry settings) of this and later generations do not tend to drift, and that needing to access a service manual should not be all that necessary - if the faults on the board are addressed - is there any truth to that?Thanks for reading, kind regards, Joe.

author: shakalnokturn
author_rank: Super Contributor
timestamp: July 12, 2019, 11:50:36 am
content: The blueish screen and retrace lines could be due to bad capacitors on the blue output amplifier or a bad capacitor near the video output IC.It can also be a sign of a weakening CRT.I haven't seen many CRT displays that will take a flash at full brightness without any blooming. In my CRT TV repair days I noticed that often replacement flyback transformers had poorer HV regulation than the originals. You could also check for bad capacitors on the HV regulation loop and watch the supply voltage to the flyback does not sag too much on a flash.A couple of photos may help identify your TV model. Any chance it could be a Daewoo WP-895 chassis?The geometry settings on TV's of that era are quite stable as almost if not all settings are software controlled, usually if a geometry issue shows up it is either a bad solder, capacitor, ferrite core gone loose, or corrupt EEPROM (sometimes due to arcing).

author: joebal
author_rank: Contributor
timestamp: July 13, 2019, 12:30:13 pm
content: Thanks shakalnkturn,Quote from: shakalnokturn on July 12, 2019, 11:50:36 amWith regards to the flash, all TV's I have played on over the years have been able to handle the brief flash without issue. I just shot a little video to better demonstrate the symptom on this unit, though it is harder to see it properly when capturing on camera, the picture takes almost a whole second to recover properly after each trigger pull. Both the picture size and brightness shrink and recover with each shot, listen for the trigger clicks to help time what you are seeing. The centre of the red part of the screen (on the right) is a good place to focus on as the effect (during camera capture) is more visible there:Quote from: shakalnokturn on July 12, 2019, 11:50:36 amI can change all the caps around the flyback. Until I can find a schematic, I am hesitant to poke around the flyback to test voltages, as I do not know exactly where to stick the test lead, and what to watch for...Quote from: shakalnokturn on July 12, 2019, 11:50:36 amI see. So it could be a few different causes... From what I've read, I'm thinking that the TDA8843 is the output IC you're referring to? I see there are about 5 small caps surrounding that one. I can go ahead and change all of them.So far I have changed the 3 electrolytics on the neck board, they were 2.2uF 250v, I replaced them with 2.2uF 450v, as that was all my local store had on the shelf. Assuming that is ok.Quote from: shakalnokturn on July 12, 2019, 11:50:36 amI had a little look at the Daewoo you suggested, but it does not appear to be the one. I decided to try and web search for the processor chip number and the term "service menu" and found other TV's that use that chip (SAA5297) and tried their button combos to reach the service menu and successfully made it in! Though I will not tweak anything until I go around replacing a few caps first. I'll continue digging around for the service manual in the meantime.I've attached a few photos, download to zoom in. Due to size limitations, I will post three shots, each in an individual post, to retain full detail.

author: joebal
author_rank: Contributor
timestamp: July 13, 2019, 12:33:08 pm
content: Second shot of the board from the other side.

author: joebal
author_rank: Contributor
timestamp: July 13, 2019, 12:38:21 pm
content: Flyback with zoom of sticker.

author: Dacke
author_rank: Regular Contributor
timestamp: July 13, 2019, 01:18:03 pm
content: I don't work on CRT TVs so I can't help much there, mostly just LCDs and plasmas. But on this cap I've circled in your picture, the plastic sleeve on the outside looks like it has shrunk, a sign of overheating. Not sure if you were just going to recap everything or not, but definitely get that guy out of there.

author: fzabkar
author_rank: Super Contributor
timestamp: July 14, 2019, 05:39:46 am
content: This chassis looks very similar:https://elektrotanya.com/matsui_25n03_28n03_ver.1.0.pdf/download.html

author: joebal
author_rank: Contributor
timestamp: July 14, 2019, 01:51:24 pm
content: Quote from: Dacke on July 13, 2019, 01:18:03 pmThanks, was wondering about that one, I didn't know the sleeves could actually shrink, I incorrectly assumed that the sleeve was just incorrectly wrapped (because the top of the cap wasn't bulging) - will definitely swap it out, I'll plan to replace all caps in the vicinity of the tripler while I'm at it.Quote from: fzabkar on July 14, 2019, 05:39:46 amAmazing!! Yeah it looks like it could be the one (even though it's for the 25/28" models), at least from looking at the neck board schematic, you've helped me realise that I replaced one of the electro caps with the wrong value. I noticed that one of the 3 electros in the diagram was a 47uF as opposed to the other two 2.2uF caps. Sure enough, I went back to the bag with the caps I'd taken off the board and there it was, a 47uF, as per the photo! Thanks for that!! How did you work out that this was the same chassis?

author: shakalnokturn
author_rank: Super Contributor
timestamp: July 14, 2019, 04:15:03 pm
content: Daewoo elcos...Either you have enough experience to know a chassis you've seen before or you're lucky with google searching "service manual + [names of main IC's]".

author: fzabkar
author_rank: Super Contributor
timestamp: July 14, 2019, 08:19:45 pm
content: Quote from: shakalnokturn on July 14, 2019, 04:15:03 pmNice catch!Quote from: shakalnokturnI can't remember what search terms I used (I tried a LOT), but I think I got lucky when I searched for one of the major ICs, as you say. Normally I search for the magnetic parts (FBT, SMPS transformer, line drive transformer, etc), but all I found was a Hantarex Polo monitor schematic which was completely different. The magnetic parts tend to be unique in every chassis.FYI, I also tried matching the FBT with other TV models at HR Diemen, but no luck there.http://hrdiemen.com/@joebal, those 250V 2.2uF capacitors are a common problem on the CRT neck PCBs in many chassis.

author: joebal
author_rank: Contributor
timestamp: July 15, 2019, 03:56:32 am
content: Quote from: fzabkar on July 14, 2019, 08:19:45 pmWhat does elcos stand for?Quote from: fzabkar on July 14, 2019, 08:19:45 pmThanks for searching so hard, I'm greatly appreciative of your effort!So from here, apart from fixing that wrong capacitor that I put on the neck board, I'm going to recap the area surrounding the flyback, and the area surrounding the TDA8843, attached photos with circled areas. It works out to be that whole side of the PCB actually. Let's see what happens! I'll do a few at a time and test.

author: fzabkar
author_rank: Super Contributor
timestamp: July 15, 2019, 04:35:29 am
content: elcos = electrolytic capacitors ?

author: joebal
author_rank: Contributor
timestamp: July 15, 2019, 04:47:32 am
content: ok, feeling pretty silly here!

author: joebal
author_rank: Contributor
timestamp: July 16, 2019, 12:55:28 pm
content: Riding on the coat tails of fzabkar's work, I found another manual, more or less the same (Chassis Professional 4400) with the added bonus of 2 pages of CRO waveforms. I've attached both files here, for future reference of anybody else who comes looking after we are long gone...There are minor circuit differences between the two (up to around 10 differences), comparing them directly with my unit shows that mine is somewhere in between these two manuals, an example I found was this, some components from one manual, some from the other - the schematic is taken from the "Power" page, the Sinudyne is the later one, the Power page being rev 3.7 vs the Matsui at rev 3.3:The tube (W76EGV023X985) not appearing in either manual:

author: joebal
author_rank: Contributor
timestamp: July 20, 2019, 02:23:53 pm
content: Progress report, been laying some groundwork, checking and marking off the caps around the deflection and video output chip area (and comparing with both schematics) - for replacement. Have made another interesting discovery, CF11 on the deflection circuit is a completely different value to both schematics, which specify a 4.7uF, but the board has a 10uF in its place:It does not have an asterisk on it, so it is not a changeable value like some of the others are. I've purchased a 4.7uF as per schematic, to replace it with, as a test. Does anybody think this could be a mistake in manufacturing?In that same diagram (up the top) is CL18 (10uF 250v), which as Dacke pointed out - has the shrunk wrapping. I've got a replacement for that one too.Also have the correct neck board cap to put in place. Will get these three electros soldered in hopefully tomorrow night.

author: andy2000
author_rank: Frequent Contributor
timestamp: July 20, 2019, 03:49:21 pm
content: Quote from: joebal on July 09, 2019, 01:56:57 pmSymptom 1 is normal. These sets have something called auto kine bias (AKB) which samples the output of the 3 guns during the vertical blanking interval, then adjusts the drive signal to a preset value. This is a good feature because it compensates for aging of the CRT which would otherwise cause the color temperature to shift over time.During the first few seconds that the CRT is just starting to warm up, it has to over drive the guns to try to meet their output target. Better sets blank the picture until the CRT warms up. As long as it quickly returns to normal, it's not a problem. If it lingers for a long time, then it's a sign that the CRT is getting weak, or the G2/screen control might need to be adjusted.Symptom 2 is probably just because Orion made budget quality TVs with weaker power supplies than say Sony, or Panasonic. It should improve if you turn down the contrast. The default picture settings tend to have the contrast at maximum, which is over driving the picture to make it look bright in the store. It's usually better to have the contrast around 1/3-2/3 of maximum. A CRT isn't going to be as bright as a modern HDR LCD!Symptom 3 also might be normal unless it's a very noticeable line. Are you seeing the edge of the 4x3 raster?There should be a picture centering control on the main board, or in the service menu. CRT TVs never left the factory perfectly adjusted, so you can usually make big improvements to the geometry with some basic adjustments. Having said that, 0.5" is well within normal tolerances. As I said, Orion was a budget brand, so don't expect top notch performance.Checking it over for bad caps, and bad soldering is a good idea. It shouldn't need a total recap unless they used really poor capacitors, but if it was used a lot some of them might be heat stressed. Don't expect any miracles since it sounds like it's working as designed.

author: joebal
author_rank: Contributor
timestamp: July 20, 2019, 11:19:54 pm
content: We've had a win!Just got back from the garage, here's what I did:1) Replaced CL18, with a 450v instead. Wrapping was quite shrunk:2) Replaced the wrong neck board cap that I put in before - CV1. (this hadn't really appeared to have effected anything).3) I noticed there were cobwebs joining all the terminals under the CRT, so I "disconnected" them:4) I quickly resoldered the red wire that comes from the flyback/tripler to the neck board, as the solder looked a little wonky. Still doesnt look the best, so I might go back and completely remove all the old&new solder from the joint and do it from scratch.So, on first powerup, I was greeted with a grey screen with permanent retrace lines. I figured this might be the G2 turned up too high - seeing as it wasnt a particular color, so I went ahead and turned it down. Perhaps this was turned up, overcompensating for a bad cap/joint previously? It looks like the flyback has been replaced at some stage, going by the flux on the joints - and the fact that the pots dont line up with the holes on the back panel housing.Quote from: andy2000 on July 20, 2019, 03:49:21 pmThis still happens, however it a bit quicker to go away, probably visible for only a second or so.Quote from: andy2000 on July 20, 2019, 03:49:21 pmThis symptom is completely gone, which I'm very pleased about! Screen is also pretty responsive to full brightness changes. I did previously turn down contrast and brightness, but it was still happening.Quote from: andy2000 on July 20, 2019, 03:49:21 pmThis is still present, very faint. Yes, only visible on 4:3 mode. However like you said, I'm wondering if after I adjust the horizontal shift and bring the picture back to the right, whether this may subside. We'll see. I think I might be just about ready to have a little tweak in the service menu.On initial powerup after repairs, there was a minor amount of glitching, on the black AV screen with no input there was the occasional hoizontal line flicking here and there, and with an image on screen the overall color on the screen changed a couple of times, but it appears after about a minute or so, this looked to have gone away. Dodgy connections, or other caps maybe?I'm very pleased with the progress thus far - very appreciative of everyones inputThe project looks very promising!

author: joebal
author_rank: Contributor
timestamp: July 22, 2019, 12:37:13 pm
content: Sad news.By this afternoon, I had the set looking great, ironed out the last issue of glitching color on warm up, by reflowing a few of the SMD components on the neck board. The TV was good to go! Ready to bring it into the lounge room.However in my striving for perfection, I went to straighten the picture a little, by twisting the yoke. There were four points where the yoke was glued onto the tube, which I hadn't come across before(circled in orange in the photo), so I used a blade to unstick them.I also loosened the clamp on the collar, and went to twist it, there was resistance around the neck, under the clamp - then I heard a nasty sounding crack under the collar clamp. Some of the plastic under the clamp broke (circled in red). Now the TV has a glitch every now and then - the picture glitches for a split second, and you hear the speakers do a little thump, like you hear if you just turn on the tv. I may have wrecked it, right at the finish line.

author: joebal
author_rank: Contributor
timestamp: July 26, 2019, 07:49:25 am
content: The crack I heard at the back of the neck when twisting the yoke was the rear part that was glued to the neck, some of those plastic bits broke, I think that the end of the yoke not being perfectly centered on the neck may have had an effect as well. I've rotated so many yokes in the past, however I'd never seen one that was glued on like this, this was a first for me.In closing, I think what has happened is that I stripped away too much of the autodag coating on the back of the tube.When I first got the tv, I could see black flakes on the PCB so it was already flaking off a little, however when I was jamming the blade into the glue bits to unstick the yoke from the tube, lots more came away. After completely removing the yoke and cleaning off the tube (before i was actually aware of what autodag was) I wiped lots of it away from under the yoke.When I put it all back together, there was no display, a continual ticking noise until the set completely shut down. Now when plugged in it cannot even reach standby mode, the red led pops on then shuts off.Pretty sad considering that every fault got resolved, it was looking good. Lasted in the lounge room for 10 hours and is now living in the garden until next hard waste collection.Big appreciation to everyone that chipped in with advice. God bless!