So, I'm an idiot.

hindered

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I just got an Astro City w/29" Nanao monitor. The picture was a little bit bowed (narrow at top and bottom, wider in the middle) which I've found out can probably only be fixed with a cap kit. This didn't stop me from going in and trying to adjust the horizontal hold pot on the chassis, which promptly broke off.

This will probably seem funny when I stop being pissed.

What are my options? I'm guessing I have to dismantle the whole thing, take off the old pot, and solder on a new pot? I'm a bit nervous about doing this -- I'm ok with a soldering iron but never did anything on a PCB... plus I'm a bit nervous about the high voltage.. Anyone in SW MI able to lend a hand or recommend someone who can?
 
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Face your fears sir.
It's not that bad. Look up tutorials online, here, Youtube, etc.. You can discharge the fly with a piece of wire and a screwdriver (household items). Order the components you need from Bob Roberts, ask for help if you get stuck. Once you've done it, you will feel a sense of accomplishment. plus have a monitor repair under your belt. Just remember: respect the high voltage but don't fear it. While I agree that people with zero experience shouldn't be messing around with a monitor. There is a huge wealth of knowledge on the net and of coarse you always have this monitor repair forum. Never be afraid to ask questions here. There is no such thing as a stupid question. In my opinion the only stupid question is an unasked one.
 
I'm also going to take a stab at this and say that if the bowing was perfectly even on both sides, chances are there may be an adjustment for it called "pincushion", or "horizontal pincushion" - on a 29" monitor they have a few more adjustments than a 20 yr old 4900. Does it have any on-screen menus?

Like the previous poster said - just take your time, discharge the tube, and be careful more than anything else. I really doubt the horiz hold pot is high voltage at all so you have nothing to worry about there, and once you discharge the tube and the chassis is sitting out for a bit it should be safe. As for soldering - installing pots are a LOT easier than most other solder jobs since the legs are a bit bigger and easier to deal with.
 
Okay, thanks for the information guys. I'm sure the pot itself isn't high voltage, but the flyback definitely is and I'll need to discharge it. I watched some videos last night about soldering through-hole PCBs and discharging the flyback and I'm pretty confident I can handle both tasks. With regards to the "pincushion" adjustment, I didn't see anything like that in the manual. The remote control board has R / G / B / Brightness, and then horizontal size and hold, vertical size and hold, and a couple of other pots (I think the 4 color/brightness and 6 other pots) and tweaking them didn't affect the bulge as far as I noticed. On the chassis itself there was some sort of vertical pot and some sort of horizontal pot, as well as 4 others that I don't think had anything to do with it. Regardless, I don't want to tweak them, as I'm pretty sure they'd just break off like this one did... Maybe I should replace them all in one fell swoop.

Some questions I haven't found answers to in my searches yet:

1) What's with the neck board? Does it just pull off and then push back on? Do I need to adjust stuff (the rings on the yoke, etc) if I remove the neck board?

2) Should I remove the entire monitor (frame, tube and all) from the cabinet, or should I just discharge the monitor, detach the chassis to work on, and leave the rest in place? I'm hoping the latter is ok, although the videos I've seen have the entire monitor assembly removed from the cab...

3) How can I tell what kind of replacement potentiometer I need? I don't have a multimeter, but would be willing to pick one up if it's what I need to do the job. I have the manual for the cab, but it doesn't seem to get so in-depth as to the actual circuitry of the chassis... And no, at this point, I'm not sure which chassis I have, and probably won't be able to tell until I get it disassembled.. there's no obvious stickers or screenprinting that I can see from the back of the cab.

4) I plan on replacing caps as well, as long as I have the chassis out. I can't find a cap kit list online (a task made even harder by the fact that I don't know the exact model of my chassis), but I'm assuming, worst case scenario, I can make a note of all the caps on the board, go to Radio Shack and pay through the nose. Is this correct?

EDITED TO ADD: I've researched and my best guess it's a Nanao MS8-29FN87, visible here: http://www.zax.com.au/spare_parts/monitor-chassis.html. Googling this model number only returns a result for the site I just linked. :/
 
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To answer your questions

1) The neck board pulls straight out from the tube. Be careful here, try not to twist or angle the neck board when pulling. Just pull straight back. The same goes with re installing it. push it on slightly don't force it if it doesn't slide in easily. You should not have to adjust or even touch the rings as those are for adjusting convergence.

2) If you can discharge and remove the chassis safely while the monitor is installed in the machine go for it. That's less work you'll have to do

3) Usually the pots will have a value on them like 103 (which is a 10 + 3 zeros) for 10K Ohm or even something like 50K for 50K Ohm. If you had a meter you could probe the two outside pins (not the center which is the wiper) and that would tell you the pots value.

4) I'm going to bet there is no way possible that you will find all if even a few caps at Radio Shack that are of the right value you will need. Your best bet is to find the chassis number/type and look for a kit. I'm sure Bob has the one you need. If you can't find it, post a pic of it here and someone will help you determine what it is.
 
ekeeb, thanks for the caplist -- I have a MS8-29 though.. maybe they're going to be similar and will hopefully save me some time.

gregatron, thanks a ton for the information. The neckboard is the part I'm most worried about at this point, though I'm sure it'll be ok... well, That and actually removing the anode cup... which will also be okay I'm sure. I've already gotten a negatory from Bob Roberts about a capkit for this monitor, although I can probably still order the caps I need from him assuming I come up dry from Radio Shack.

I'm out of town for a couple of days and won't have time to look further into this until Sunday... which doesn't jibe well with my OCD-must-fix-this-right-now personality. I hate having my new toy sitting there all blind and dark. :)
 
When pulling the neckboard, make sure there isn't any silicone goo stuck to the neck of the monitor and the neckboard. If there is, take a sharp razor knife and WITH THE POWER OFF slice thru the silicone between the two to make taking the neckboard off that much easier. I have seen too many neckboards snapped in half from people htat pulled too hard. A very gentle wiggle from side to side seems to help. If you can get your fingers in there, put them on each side of the socket and push the neckboard off it is is stuck. HOWEVER, if there is a shield behind the neckboard, don't slam it into the shield and break it.
 
OK GUYS! I got everything discharged and apart... based on my best guesses and testing with a multimeter the broken pot was 1k ohms. I went to THE SHACK and bought a new pot.. desoldered the old one... soldered the new one in... got rid of all the dust with a can of canned air... hooked everything back up...

Works fine. Turn the pot too far to the left, and the vsync goes out of whack... too far to the right, same deal... in the middle, we're good. Sounds like the pot itself is fine, and I'm happy.

HOWEVER.

It seems to take a little bit longer than before to warm up.. and there's a clicking noise of static while it's warming up... starts out fast and slows down... like.... cliclicliclcilcicliclickclickclick click click click click click click [edit: those clicks are supposed to get further apart but this helpful website cut out the white space :p] and it keeps clicking a litle bit after the picture appears... sounds like static electricity shocks. The monitor was definitely not doing this before. Every time the static pop happens, the image kind of distorts and I see a line across the monitor.

EDIT: I just doublechecked everything and powered it back on.. big POP on powerup, then some smaller clicks.... when I powered down it made the clickclickclicliclickciclik sound... I was watching and didn't see any arcing.

Ideas? What did I screw up? :)
 
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Here's some images... first two show the chassis in the machine and you can get an idea of how much dust was in there...

Third pic shows the metal frame the pcb connects to... do those discolored spots look like arcing to you? That corner of the metal frame corresponds to the components shown in the 4th picture (the closeup, clean, pcb). This corner is where the degaussing coil connections are... is it possible to connect the wires to degaussing coil backwards? The connector in this machine can go on either way and both wires are red...
 

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Sounds like you may have not had the neckboard ground hooked back up when you re-installed the chassis. But I think that would spark or be pretty obvious.

Also when you realized that it didn't sound right, did you immediately turn it off and pull it back apart and check for problems?
 
Sounds like you may have not had the neckboard ground hooked back up when you re-installed the chassis. But I think that would spark or be pretty obvious.

Also when you realized that it didn't sound right, did you immediately turn it off and pull it back apart and check for problems?

I'm not sure about the neckboard ground.. I don't remember seeing any place on the neckboard that is missing a cable or connector, and I don't remember unattaching anything from the neckboard itself, though I'll give it another look tomorrow evening.

After hearing the noises/seeing the distortion, I immediately turned it off, and then I turned it back on again a few minutes later to further diagnose.. heard a POP like a big static discharge and then the repeating clicking/smaller static discharge noise as it powered down again... I took it apart and checked.. everything looked ok to me... I cleaned more dust off, "repaired" a couple of joints that may or may not have been cold, and I haven't reattached it to the tube yet... it's still sitting on my table.
 
Just make sure this wire is connected to the chassis/neckboard somehow.
 

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Yep, that wire was connected to the chassis.

EDIT: ALTHOUGH.... In that picture, it looks like the wire is connected to the neckboard -- You might be spot on. I'll doublecheck the neckboard tonight.
 
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:O

Thanks bjk7382, you hit the nail on the head.
 

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:O

Thanks bjk7382, you hit the nail on the head.

No prob, better than hitting my thumb I guess :)

I always go thru a rundown before I power up a monitor after re-installing the chassis
-Power
-Neckboard
-Neckboard Ground
-Yoke
-Anode
-Video Input
-Any extra wires, like on a sanyo for the sound, or on vectors for the chassis transistors
-Deguass wire
 
No prob, better than hitting my thumb I guess :)

I always go thru a rundown before I power up a monitor after re-installing the chassis
-Power
-Neckboard
-Neckboard Ground
-Yoke
-Anode
-Video Input
-Any extra wires, like on a sanyo for the sound, or on vectors for the chassis transistors
-Deguass wire

Yeah, that's a pretty good checklist... Problem is, I sort of remembered pulling the ground off the neckboard, but couldn't see where it reattached when it came time to reinstall everything.. And the last thing I checked was the Degauss wire this time... damned if you can't attach the thing while the chassis is properly seated because the tube is in the way, so I had to get down, unscrew the whole thing, rotate it, attach the wire, and reseat and screw it down again. :\ Oh well, it works perfectly now..

EXCEPT. A little bit of curl on the top, both right and left side.

The curl gets worse if I tweak the newly installed pot to the left.. and gets better (but never goes away fully) if I turn it further to the right. I read something about a screen curl hack.. adding resistance to the pot. Would it help in my case? Could I just install a pot that has more built-in resistance? Although, I think the next smallest pot is 10k ohms and it would probably be nearly impossible to dial in to a proper amount of resistance.. Ideas anyone?
 
The curl gets worse if I tweak the newly installed pot to the left.. and gets better (but never goes away fully) if I turn it further to the right. I read something about a screen curl hack.. adding resistance to the pot. Would it help in my case? Could I just install a pot that has more built-in resistance? Although, I think the next smallest pot is 10k ohms and it would probably be nearly impossible to dial in to a proper amount of resistance.. Ideas anyone?

Here's the screen curl hack I was referring to: http://girasoli.org/arcade/?p=265

However, since turning my 1k ohm pot all the way to the right causes the picture to go out of whack, I'd assume adding resistance would have a similar effect?

I'll try to post pictures tonight. Oh, and btw, I never did the cap-kit. Just glad to have it up and working again for right now.

EDIT: Oh, Orion3311 -- you might be onto something... according to http://slawdog.com/chris/remote/MS8-25F -29F Manual.pdf, it looks like there is indeed a pincushion control on this chassis! Unfortunately, several of the pots on the chassis are covered in this chewing-gum-like substance that stops the dials from turning. If that's the case with this one, I'll just leave well enough alone...

Thanks again to everyone for the information and encouragement -- I couldn'tve done it without you, and now I have the confidence to tackle any future repairs as well.
 
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A nice pair of electronics cutters or a razor blade will take care of the "don't touch this" stuff :) Also sometimes you can get lucky and it'll just peel off.
 
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