New Life Games LLC
Monitor Repair Log and Database. **Arcade and Gaming** => LCD and CRT Monitor Repair Tech Support => Topic started by: shortrackskater on February 25, 2015, 11:38:21 AM
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I recently bought another Game Maker. It's an earlier model with a 13" Tatung monitor.
My camera "removed" the discoloration on the white cards but it's clearly visible to the naked eye, that the white is very yellowish. The other issue is there's tearing and horizontal lines at the top of the CRT. None of the adjustments do much. Also, for the best picture, in its current condition, you have to have the brightness and contrast all the way up.
I'm not as knowledgeable on monitors but I guess it's time for me to learn some more.
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You probably need to recap it for the weird sync issues. As far as the color, that is another story.
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I read an old post where there was "too much blue" and the reply was to warm up the tube, then lay it on its face and tap the neck with a screwdriver...
UPDATE:
I pulled the monitor, and made sure the RBG controls were marked. Then I just sprayed the pots and turned them a few times. My white is back. The colors are fine now.
Still - I wonder how hard it is to locate a replacement monitor? I've never recapped although I do have good soldering skills. The monitor is a Tatung VS-14428.
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:bump_2:
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Does anyone know a place or person who would either fix this one or trade mine and $$$ for a working one?
Is there anyone here anymore?
A year ago, I'd have 4 replies... what the heck has happened to NLG? :gloomy:
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Is there anyone here anymore?
A year ago, I'd have 4 replies... what the heck has happened to NLG? :gloomy:
Wednesday nite, everyone is
1) at church
or
2) bowling & drinking !@!??? :garfield:
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I recently bought another Game Maker. It's an earlier model with a 13" Tatung monitor. My camera "removed" the discoloration on the white cards but it's clearly visible to the naked eye, that the white is very yellowish. The other issue is there's tearing and horizontal lines at the top of the CRT. None of the adjustments do much. Also, for the best picture, in its current condition, you have to have the brightness and contrast all the way up.
I'm not as knowledgeable on monitors but I guess it's time for me to learn some more.
on the brightness issue,
If that is a crt monitor then after several years of no telling how many thousands of hours the cathode on the gun just starts running out of electrons to emit or it gets a coating that blocks emission. Either way your stream of 'trons gets weaker. And that reduces brightness. Sometimes on the monitor circuit board running things there is another master adjustment for brightness limiting (it is set at the factory to limit how much the operator can crank up the brightness) and you can increase it a little to make your front brightness adjust not be at the end of its range. Sometimes you can also up the high voltage adj a little so the electron beam is attracted more strongly to the front of the screen. But all of this is a bandaid for a crt that's just got a lot of miles on it. Also, there is a phosphor coating on the inside of the screen that glows when the electrons bombard it. The phosphor gets weaker as the decades go by.
Be careful, if you crank things too far you can get blooming or other problems. AND be careful noodling around in there, even with power off the crt holds a large charge enough to shake your pickle.
Actually the brightness on it looks pretty good to me. It doesn't hurt if the brightness pot is at the end of its range as long as you are happy with the brightness level. I'd concentrate on the tearing at the top of the screen. I agree with rick that cap replacement takes care of a lot of problems on older crt monitors. There are place that do cap jobs, maybe one in your town. Check with any tv repair shops that are still around, computer monitor repair places or even arcade places to see if they know anyone that does that kind of work.
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AND be careful noodling around in there, even with power off the crt holds a large charge enough to shake your pickle.
Oh my, "shake your pickle"...that has to be the best saying EVER... :24: :24:
Thank you rokgpsman! You have made my night!
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AND be careful noodling around in there, even with power off the crt holds a large charge enough to shake your pickle.
Oh my, "shake your pickle"...that has to be the best saying EVER... :24: :24:
Thank you rokgpsman! You have made my night!
you're welcome Roz,
glad to see you got back from church tonight all safe & sound,
feel free to shake a pickle of your own...
[and that could really make your night].....(don't want to offend any of the genteel users)
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Mine too!
I'll try the brightness master and see if it makes a difference. It seems just a tad low.
I did try a couple TV repair places near my home. One didn't answer, one said he didn't work on Tatungs! :hissyfit:
If it's not too expensive, maybe I will buy a cap kit provided I can find a source. It might be fun!
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If it's not too expensive, maybe I will buy a cap kit provided I can find a source. It might be fun!
this might be close to what you need:
http://www.ebay.com/itm/Tatung-VS-14428-VT-1440S-Cap-Kit-Get-Well-Kit-for-Monitor-Repair-/200889563465 (http://www.ebay.com/itm/Tatung-VS-14428-VT-1440S-Cap-Kit-Get-Well-Kit-for-Monitor-Repair-/200889563465)
and more info is attached, hopefully for your particular VS-14428 monitor:
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Your one step ahead of me! I just saw that on ebay and was about to post!
Thanks!
Although... looking at my monitor... I don't want to damage my pickle! I've never taken out a circuit board out of a CRT.
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To remove the monitor main board you have to disconnect it from a few things associated with the crt. If you don't feel like doing this then you shouldn't. Look it over and figure out the least things you have to disconnect. There is often a small board or assembly on the narrow end of the crt, it has some cables that go to the larger main circuit board. Remember, just because it is turned off and unplugged there is usually voltage still stored in there ready to bite you.
There is usually a cable that is taped or wrapped somewhere around the entire backside of the big end of the crt. This cable should have a connector for plugging into the main circuit board. This is the degaussing coil that demagnetizes the crt each time the monitor is turned on, it helps with the purity of the screen image.
The scary part is the crt hi voltage cable. While the monitor is operating it is roughly 1,000 volts per inch of size on the screen, so figure on 13,000 volts or a little more. When the monitor is turned off this voltage is still stored inside the crt itself, it acts as sort of a capacitor for all of that electrostatic charge that was on it. There is a heavy round wire, a lot of times it is red, that connects to the side of the crt glass. This is the high voltage lead to the crt. There will be a round rubber suction looking piece at the end of the crt hi voltage cable. There is a metal clip under that round insulator, it fits into a hole in the glass on the side of the crt, usually on the top side somewhere. Removing it is where you have to be the most careful because that clip attaches to the high voltage lurking inside the crt. Although the electrical current capability is relatively not that much the voltage is so high it is still dangerous. Some guys use rubber gloves and insulated tools like needle nose pliers to remove this hi voltage lead. You don't want to use anything conductive like a screwdriver blade. Hopefully you just pinch and twist on the rubber cap and the connection comes loose. There are ways to discharge the tube and get rid of the high voltage, this is especially needed when the crt is getting replaced, don't want a dangerous old crt sitting around to hurt someone. You can google "discharging crt" to see how it is done but it probably isn't needed since you just want to remove the main circuit board and replace the caps. Depending on the room it might even be possible to replace some of the caps without even removing the circuit board.
Below are some generic pictures to give you an idea, your monitor will be similar but not exactly the same.
BEFORE you do this I think you need to think about it carefully and maybe get some opinions and tips from others here. This is a for-real, no-sh*t-sherlock kind of deal that can ruin your day if it goes wrong. It isn't like dinking around with other mechanical parts of the machine and seeing how it goes. You have to be careful and only have to make 1 mistake to get your teeth chattering.
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While you were writing this probably, I was watching a few videos on discharging the voltage from the CRT, and also how that anode connector comes off.
It doesn't look so bad now... I think I can do this!
I'll look close at the pictures and probably do some more reading. I'm also not sure which caps go where but since that kit is specific to the monitor, I'd assume I can just find them all and then replace them one at at time.
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Usually the circuit board will have writing on the board next to the capacitor saying something like "C9". So hopefully the kit will have a paper listing the capacitor designations (names) of all the caps that get replaced. Also, the value of the cap is written on the side of the cap, you should check it with the one you will be replacing it with as a double-check to make sure they match and that you are using the right part at the right place. Also, many caps are polarized, meaning they have a plus and a minus (positive & negative) side. Important to get the plus lead in the plus hole.
attached is a bare board that shows how they write the component designation name on the board itself and another picture of a board with parts soldered in.
also attached are photos of polarized capacitors. Notice the first one has negative signs (minus signs) written along one side that align with the shorter lead. The second cap has a + mark by the positive lead. On polarized caps there will be a marking that shows the negative or the positive lead. Keep in mind that there are capacitors that are not polarized, you can install them in either direction, so they won't have polarity markings.
When doing a monitor recapping job most (or all) of the caps will be polarized, as these are the usual type of filter caps that dry out over the years and go bad. There is a moist chemical paste inside some capacitors and that chem is what dries out. As the cap goes bad it can develop internal resistance and run hotter, this can dry out the cap and it stops working. Or if there is enough heat it can cause the moist chem to evaporate quicker and create gas pressure inside the cap body. That sometimes causes pressure to build up too much inside the sealed cap and the flat end will start to bulge and can eventually rupture. A rounded or bulging flat end to a cap can indicate it is failing.
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Thanks for the pictures! This definitely helps. Cap kit is on the way. I'm doing this. :applause:
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Thanks for the pictures! This definitely helps. Cap kit is on the way. I'm doing this. :applause:
Good luck with it and let us know how it turns out.
channelmaniac here on NLG may be able to help with specific questions if you run into problems.
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Thanks for the pictures! This definitely helps. Cap kit is on the way. I'm doing this. :applause:
Bally crt monitor discharge procedure:
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A clip lead from the shank of the screwdriver to the grounding strap on the tube helps a lot.
But then again, so does a high voltage probe...
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Yep, all true.
The guy I worked with used to say "First you set your coffee cup down"....
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I did watch a few videos on discharging. Seems fairly straight forward. Thanks again. Looks like my cap kit will be here early next week.
:lightningbolt: :lightningbolt: :lightningbolt: :lightningbolt: :lightningbolt:
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I did watch a few videos on discharging. Seems fairly straight forward. Thanks again. Looks like my cap kit will be here early next week.
:lightningbolt: :lightningbolt: :lightningbolt: :lightningbolt: :lightningbolt:
Did you order a full-length HazMat suit too? :garfield:
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:lol: :lol: I'm going to wear my aluminum foil suit and hook a second lead from chassis ground to my earlobes!
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ok, I see you have everything well planned & under control,
my job here is done. :cool_thumb_up: :waving_flag:
[but if I see a bright flash on the horizon in the next few days I'm gonna wonder]
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That's second. First you make sure the tv is powered down, trust me on this...
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I have begun!
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Excellent!
Let us know if you find any with a bulging top.
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Hmmm I wouldn't mind finding those kind ... :yes:
However, I have already run into an issue... there's TWO C906's! Both same value. I replaced one and then found another on the neck board.
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Does the cap kit have enough of that value to take care of both C906's?
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no... I guess I can just go get one... strange though...
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yes it is odd. Any chance the masking is wrong, that one of them is actually a different CXXX and you will have enough caps? You can contact the guy you got the kit from, see what he says.
It is hard to read but are these the two C906's you found?
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Yes... and just pulled off the neck board. The inside is labeled C905! Outside is C906!
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BUT... what I pulled out of the C905 hole was a 100uf cap and not the 4.7uf!
Would this have worked for however many years being the wrong value? :Scratch-Head:
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That's a big difference in value. Does the kit have an extra 100uF? The kit list shows C905 to be 100uF, right?
On the other C906 (the real C906) you put in 4.7uF?? Or the other way around?
EDIT: schematic and a repair guide later showed that C905 should be 4.7uF 50v and C906 should be 100uF 25v.
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Yep ... shows to be the 4.7uf
No extra 100uf's.
And here's the proof... I've only replace 4 caps so far so I have kept track of what I pulled out...
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Is there a Tatung part number on that neck board,
maybe I can find a schematic of it?
As you replace each cap might be a good idea to double-check the writing on both sides of the board to see if they both match on the CXXX number for the cap. Did the other C906 say "C906" on top side as well as bottom?
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T-003
Monitor is Tatung VS 14428
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BUT... what I pulled out of the C905 hole was a 100uf cap and not the 4.7uf!
Would this have worked for however many years being the wrong value? :Scratch-Head:
Maybe it would have been fine if it was just a filter cap and 4.7uF was going to be good, the 100uF would have just been extra smoothing, not needed but didn't hurt anything. Depends on the circuit.
EDIT: turned out C905 was a DC blocker/coupling cap so value was not critical.
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T-003
Monitor is Tatung VS 14428
T-003 is all that's written on neck board for a p/n? I try searching for that, as well as Tatung VS 14428 neck board.
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Found this, it says C905 is 4.7uF and C906 is 100uF. Also lists value for a bunch of other caps, neck board and on main board. Hopefully it matches what the cap kit list shows.
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Well that confirms what should be there.
And, what I pulled out was the value for C906!
Interesting.
And thank you!
I wonder if I should just do the neck board and see what happens?
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I wonder if I should just do the neck board and see what happens?
That's a thought, I wouldn't think it would hurt anything.
here's a picture that came up on google search, supposed to be the equivalent neck board, it is used on a 14" Tatung. Does it look like yours? The photo was not too sharp, so is hard to read the component writing on the board.
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Here's mine... looks like it.
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It sure does look like the same board. I'm still trying to find schematic for neck board. I've seen a lot of requests for it, the answer is always a referral to contact a company called Merit, I think they own Tatung or do their service work. But this gives me another neck board part number to search for schematic.
Since the main problem you have with your monitor was the screen image tearing at the top then the problem may be on the main board, in the vertical (or horiz?) section. So just doing the neck board might not fix that. But you can try it after completing the neck board part of it to see what happens.
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Well it didn't explode! But the original problem is still there.
So I'm on to the main board. I think I'll save that for Friday though...
THANK YOU for all the help and support, so far.
Still that's strange on that cap being the wrong value. I wonder if it was put in that way originally when, whoever did the assembly, they just put in the value for C906?
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Still that's strange on that cap being the wrong value. I wonder if it was put in that way originally when, whoever did the assembly, they just put in the value for C906?
You're probably right, someone at the factory saw the C906 written on bottom of board and looked at their list, inserted the 100uF cap.
Hard to say if it would make a difference without seeing the schematic. Just so I am clear, what value caps did you install for C905 and C906 and did it match what the cap kit list said? The guy you got the kit from may have schematics of the monitor, including neck board. Or maybe not. Wouldn't hurt to send him an email to see, while you take a break from soldering.
I did find a schematic of the neck board - I think - but it is just about unreadable. Looks like the worst scan ever. And the original drawing was made back in the day when the writing was done manually by hand, so it really gets blurry when enlarged. Check it out:
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C905 is now a 4.7uf 50v and C906 is a 100uf 25v
Oh my! Impossible to read. It looks like cuneiform. :rotfl:
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Whoa! I think yours is closer to making sense. I'll check back in on your next part of it.
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:thank_you:
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C905 is now a 4.7uf 50v and C906 is a 100uf 25v
well, I had too much caffeine, so continued to look into this, here's more info.
I found a readable Tatung neck board schematic that looks similar to yours (I think). It does show that C905 is 4.7uf and C906 is 100uf, which matches what you have. So maybe you can use this schematic as a guide even if it isn't exactly for your neck board it may be pretty close. It shows that C905 is just a coupling cap, blocking DC but allowing the BLUE video signal to pass thru, so it may not have mattered much if it was 100uF instead of 4.7uF.
Next I found a repair blog where someone had a screen image with horiz tearing at the top, similar to yours. They had done the recapping but it didn't fix it. It was suggested to them to carefully check the resistors in the vertical circuit around IC701 LA7837, especially C714 and R720, circled in the center of the attached schematic. They also said a bad or leaky diode D702 has caused this problem. On your main board these parts may have different designators but hopefully they will be similar parts. Anyway, the guy said replacing C714 fixed his screen tearing problem. He said it was a Mylar cap, 100v. I don't know if C714 is in your cap kit, but after you are done recapping if the tearing problem is still there this might be something to look into.
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Just finished the re-cap. I'll check those other things now...
Where the hell did this insulating washer drop from???
Update: I didn't see anything obvious, but during my recap, I did see a LOT of bad solder joints, which I repaired. It appears this has been recapped somewhat... some I replaced but others that weren't part of the kit I got.
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Well crap... now I have the same tearing with a nice RED screen. I tried adjusting the RGB in the back separately (since I have to pull the CRT out) but didn't get any change, unless it's a combination of all three causing this. I need an extension cable.
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Odd that the screen color would change. That was C905 that you found they had put in a 100uF instead of 4.7uF, and it is in the Blue video input. I wonder if when they aligned it they had to set it differently since they had the wrong cap in there for C905? Not sure, didn't think it would matter. You can always reinstall a 100uF back in for C905 (like they had it) just to see if it affects screen color. On the equivalent caps in the Red and Green video input (C903, C904), did they also get changed in the cap kit work? If not, are they 4.7uF or 100uF?
Are you saying that adjusting the Red, Blue and Green video input pots (R950, R952, R953) didn't affect the screen colors? Or is it the pots R936, R937, R938?
We may need to get someone more familiar with monitor alignment than I am to give an opinion.
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Based on your picture you lost your green gun on the crt, blue and red are there. And quit messing with the crt board, it has absolutely no effect on picture size(vertical/horizontal)in any case. Those things are controlled through the yoke. Any stretching, shrinking, tearing, etc will be a product of cap, resistor, diode or IC problems in one of those circuits. If you can get your color straightened out I would find the pin out diagram for the vertical output IC and check all your voltages while it's running and go from there.
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The problem is that I've never worked on a monitor before! So I just bought the cap kit and replaced everything. I had no idea that the CRT board didn't affect picture quality... :no:
Well, at least I learned how to tear a monitor completely apart and get it back together again.
I'll reinstall that different value cap and see if the color returns, then I'll report back.
Thanks cowboygames and rokgpsman.
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You could check to make sure all the connectors going to both boards fit properly, don't have a pin that got pushed back or bent over and causing the loss of the green signal. A cable or wire could have gotten tugged on or pulled while you had it apart. In particular check the cable carrying the red, blue and green signals from the main board to the crt board.
Also, you could check or replace that cap, diode and resistor I mentioned in an earlier comment (#49) that fixed the tearing on the other persons monitor from another repair blog. They are located in the vertical circuit.
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BUT... what I pulled out of the C905 hole was a 100uf cap and not the 4.7uf!
Would this have worked for however many years being the wrong value? :Scratch-Head:
Maybe it would have been fine if it was just a filter cap and 4.7uF was going to be good, the 100uF would have just been extra smoothing, not needed but didn't hurt anything. Depends on the circuit.
EDIT: turned out C905 was a DC blocker/coupling cap so value was not critical.
Okay I pulled out the cap in the mismarked C906/905 hole and put the 100uf back in. The color is back to normal. Now I'm back to the tearing at the top.
So this cap actually IS C905 i think... and it did make a color difference... I'm confused now with it being a DC blocker. On the neck board, this cap is at the top of a line up of caps C903, C904
Now I'll check things from the earlier comments...
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That schematic we are using may not be the exact one for your neck board, or there may have been changes and updates to your board after that schematic was made. For whatever reason it looks like the 100uF works better. Are the caps at C903 & C904 also 100uF? They are the similar caps in the other color signal inputs.
As cowboygames said, the tearing in likely to be caused by something in the vertical circuit on the main board. That repair blog I referred to earlier said to check or replace things in the C714, R720, D702 area of IC701. Also, Q701 is right there in the same circuit and it may be the vert output transistor cowboygames mentioned.
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If you're not familiar with circuit board numbering systems, in this case all vertical circuit components will be 700 series numbers. Makes it easier to pick them out of the jungle on the board versus following traces
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Caps C903 and 904 are 4.7uf
This board looks like it had some revisions/rework done as well since there one cap just soldered on the back of the main pc board.
Okay I'll take out the main pc board and check those areas.
Funny... I was (sort of) looking forward to hearing a ZAP when I discharge but, so far... no :lightningbolt: :lightningbolt: :lightningbolt: sound. Do these particular monitors self-discharge when powered off? It only sat a little while and I got nothing. I'm making sure there's a good connection to chassis ground too.
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That's curious about C903 & C904 being one value and C905 being a different value. Wish we knew for sure that the schematic is the right one. I think it is real close but it may have different designators for the various parts.
I don't think crt monitors are made with a self-discharging method. The charge inside the crt is electrostatic so it will decay over time but the ones I've messed with still had some charge even a day after they were last powered up. Just to be safe always take safe precautions and assume it does have a charge until you have manually discharged it. As soon as you figure it will be ok to take a shortcut is when you get bit by it.
Hoping you will find something in the vertical circuit that fixes the tearing problem.
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As cowboygames said, the tearing in likely to be caused by something in the vertical circuit on the main board. That repair blog I referred to earlier said to check or replace things in the C714, R720, D702 area of IC701. Also, Q701 is right there in the same circuit and it may be the vert output transistor cowboygames mentioned.
I can't find Q702, only Q701. I did find D702 and it checks good with my meter on diode setting. I found IC701 but have no idea how to check it. R720 measures 195 ohms... I think, if I'm reading my meter correctly. I'm not really sure what else to do here. Shot two pictures. Q701 looks either like it's been hot, or it's just the PC around it being heated by R774
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I don't think there is a Q702 on the schematic, did I typo about it somewhere? Q701 is the one to worry about.
R720 is 140 ohms on the schematic, does it have any writing or markings on it that you can read to make sure what value it is supposed to be? Also, did you lift one end of R720 to measure it, that's the only real way to measure it truly. If it is reading 195 ohms in circuit then you know it will measure even higher resistance out of circuit. If R720 has increased in value a lot then it could be due to too much current going thru it and thru Q701, over heating them both and changing the value of R720, which now changes the way the circuit works, possibly causing the tearing image problem. Of course, this is just a theory....
The darkening of the board around Q701 makes me think it is from Q701 getting hot, not so much from the 82 ohm R774 nearby. So if Q701 got that hot I'd be suspect of it, might be breaking down during part of the vertical signal and causing the tearing. Maybe you can replace it. And also check the other parts around Q701 like R729, R774 and pot R773. R774 is a 2 watt resistor so that means there is some heat in it and current thru it and Q701 normally. That circuit part labeled YV1 and YV2, is that the yoke windings for vertical deflection? You are at the point of just checking things in that area and replacing anything you aren't sure of, that's the only way to eliminate it as a possibility. Resistors can be measured, but caps and IC's you really don't know until they are replaced.
Take a look at that picture I posted a few comments back (post #49) of the screen tearing at the top and compare it to yours. That guy said he replaced R720 and C714 and it fixed it. He also said a leaky D702 can cause problems. Only you can decide how far you want to go with this, I know you have other stuff going on. But you might be right there on top of the problem and just need to change a few more parts to fix it. Based on that other guy's repair I'd think about changing R720 and C714 and maybe Q701 before ending the effort on your monitor.
But whatever you decide to do will be ok. You can probably get a replacement monitor, even a used one and get things back up & running. A lot of people would choose that way rather than give repair a try.
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Thank you, again.
I think I'll give this a try. It's already apart again. I can't see the ID on the transistor. Is it C1213? I don't remember anything on parts anymore. I only knew these numbers a zillion years ago when I was at Rockwell. :(
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The schematic shows Q701 as a C1213 transistor. If you can't find anything on it we can check a cross-reference. There may be a place that sells electronic parts in your town, also ebay, Jameco, Mouser, etc.
I just checked the cross-reference, a C1213 is also known as a NTE289 transistor. Did you check for bad resistors in the vertical circuit, especially ones around Q701? If a resistor has opened or increased in value a lot then that could cause a new Q701 to overheat. You can lift one leg of a resistor from the board, measure it with ohmmeter, then resolder it if ok.
Looks like the new NTE289 transistors sell for about $2-$3, then a shipping charge.
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I was able to buy c714 which I hope is a .10mfd 100v cap (I took part of the schematic to the parts place) and D702 which says 10df4 on the schmetic. The replacement diode says NTE574 D041 which replaces ECG574.
I have no clue on these numbers.
They didn't carry the transistor. I'm looking on ebay and see some that say C1213, or C1213a, and NTE289 as well.
I'm wondering if I should replace the cap and diode I have now (if they're correct!) and see what happens or find the transistor and do all three?
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ECG was the standard cross-reference for semi-conductor parts for a long time and a lot of places still use it but NTE is replacing it. Either one should work fine for getting the right parts. I did a quick search on internet and diode 10dF4 does come up as NTE574. Be sure to install the diode the correct way, with the diode leg nearest the band on diode body in same solder hole as the old diode or use the marking on the board. (you already know this, just a reminder)
Since you have these 2 parts I'd be tempted to install them if it was me doing the work. Just keep in mind this is a bit of a gamble, don't leave the monitor on too long if you still see the tearing on the screen. That old Q701 probably isn't completely bad since you do get a fullsize vertical picture but it may be running hotter than it should. I'm surprised the store didn't have the transistor but I guess they can't carry everything. If you try this and the screen still has the tearing I'd try replacing Q701 next.
I think the C1213a is just a higher power (or voltage) spec'd version of the C1213, probably would work fine. The guys selling the parts should be able to give advice by comparing the specs listed in their catalog/database. They get questions like that on parts they sell.
Good Luck!
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If only the IC is bad you'll be ok doing that. If you have a resistor breaking down under load or a bad diode then it will trash the new vertical output IC. I would put a meter on the diodes in that circuit and see if you have a bad one. A bad resistor may or may not check bad without a load on it. Signs of excess heat around resistors isn't uncommon, but it will be common to all similar boards in the same area if they just run hot in that area for whatever reason. It's not a sure sign of a problem. Best bet would be if you had the pin outs for the vertical output IC, LA####, and could check the voltages on it with the monitor running.
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I did get the transistor ... it's an NTE 289a.
At this point, I can replace the three parts mentioned. I don't have any extension cables to check running voltages.
Should I just replace the parts and see what happens? I'll remove the resistor and check it out of the circuit. The diode tested good on my meter but it was still in the circuit.
Gah!
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Diodes will check good or bad in or out of circuit, but if it checks bad I'll pull one leg up to make sure another component isn't the cause. Resistors check the same in or out of circuit, but can open under load, that's why it's better to check the voltage on both sides while it's running. RCA had a huge problem with resistors that checked good but broke down under load. Ultimately, if shotgunning the circuit is your only good option then ya gotta do what ya gotta do. If it gets to frustrating or expensive, send it to one of the companies that rebuilds boards. Seems like they've been mentioned on here before, but that might have been for LCD's
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All the diodes tested good. I went ahead and replaced C714 and Q701.
I got this...seems to be a working monitor!
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Good job :applause:
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Looks good from here! :cool_thumb_up:
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Thank both of you for holding my hands through this one!
I'm wondering if it was the cap or the transistor?
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Thank both of you for holding my hands through this one!
I'm wondering if it was the cap or the transistor?
I am too. There are transistor checkers and cap checkers but you'd have to locate one. The cap or transistor could have been breaking down during the vertical retrace and that carried over for a few lines down the top of screen. If either part shows physical change like cracked or overheated that could be a clue. In the shop a lot of times we'd change 2 or 3 parts at the same time in order to do the repair faster, since the parts cost less than what the time spent going one by one would cost. But never know for sure which part was the actual cause of problem. My guess would be the transistor but it's just a guess.
You could put one of the parts back in and see if it still works or begins tearing again. NOT! - That's a Bad idea, you got it working, so I'd leave it alone. :yes:
Was your adventure with this worthwhile for the experience? I'd say yes but your time spent may have taken you away from other things you'd rather been doing. But it is good for one's confidence, tackling something new and having success at it. That's a big plus I think.
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I actually thought about putting the old transistor back in! But nope, not gonna do it!! Perhaps if I had better test facilities, rather than the garage bench, and constantly moving laundry around to clear more space. :)
I really want to make up some extension cables for IGT and Bally too...that's on my list.
As for the time and trouble spent here, I would do it all again in a heartbeat. Thanks to you and cowboygames, I was able to rid my fear of CRT's. I still know next to nothing on them but at least know, I know a little more...and I can tear them down, discharge, and put 'em back together too. :thank_you:
Note: I changed the topic name to reflect the actual item issue. There's way too many mismatched topics on NLG. I wish we could do a "clean up" day here sometime.