monitor repair: cap replacement

yea, so um. im sick of my monitor not displaying red. i cant find anywhere to fix it, so i decided to do it on my own.

first of all yes, i can solder.

now. is it safe to take the neck board off of the monitor with out dis-charging it, or do i have to dis-charge it.

also, the caps do got on the neck board right? <IMG SRC="smilies/wink.gif" border="0">

finally, where can i get a cap kit? i know i have either a wg or happ controls monitor (not sure...gotta check) also does the cap kit come with instructions?

thanks for helping the monitor technician newbie <IMG SRC="smilies/glee.gif" border="0">

[ August 03, 2001: Message edited by: sonic1687 ]

Okay...I can't answer all of the questions, but I have removed the neckboard without discharging the cab..,not sure if you are supposed to, but it didn't kill me.


Not sure where the caps go...that's why I use the TV repair guy. I'll get you that number this weekend.

<IMG SRC="smilies/smile.gif" border="0">

What size is your monitor? I just got a brand new chassis for my 29" monitor, since the colors were getting a bit dull, I got it for only 35 bucks new from a taiwanese company (Cause they don't make 29" arcade monitors in the USA).

Instead of installing the cap kit, which IMO is a hassle, I'd just buy a new chassis, and swap it out with the old one.

A good place for cap kits is www.happcontrols.com. Comes with detailed instructions for replacing the caps.

Dammit..... NEVER work on a circuit involving a monitor without discharging. Those things carry 20-40KV - yes, that's 40,000 Volts!!! This charge can remain and hurt you. And guess where it stays.... devices designed to retain charge... yup, capacitors!

No such thing as a 'cap kit' (as far as I know). Just find the values from a service manual or direct off the capacitors and replace with the same components.

Originally posted by eggplant_casserole:
<STRONG>Dammit..... NEVER work on a circuit involving a monitor without discharging. Those things carry 20-40KV - yes, that's 40,000 Volts!!! This charge can remain and hurt you. And guess where it stays.... devices designed to retain charge... yup, capacitors!

No such thing as a 'cap kit' (as far as I know). Just find the values from a service manual or direct off the capacitors and replace with the same components.</STRONG>

Click to expand...

Eggplant is right, its better to be safe than sorry. There is a guy called Bob Roberts who sells the caps in kit form. What this means is that you tell him what monitor you have and he sends you every cap you need , plus also a diagram showing you where they are positioned.

I'm sorry i dont have his web page , but do a search and it'll pop up or ask in the arcade newsgroups.

My cap kit cost me $12 incl postage3 to england so its not expensive.

If in doubt get an electrician or tv repairman to dischage the board for you as well

Bri

Discharging a monitor is very simple. There are faqs on how to do it all over the net.

Also if you leave the monitor off and unplugged for a week or so before you need to work on it, you'll hear pretty much no sound when discharging it. Since it most likely dicharged itself while it was off.

of course there's such a thing as cap kits. many places offer complete capacitor kits with all neccessary caps in one set and a sheet with locations usually.

also, the charge is held in the tube, under the suction cup on the back in fact. the smaller caps only hold minimal charges.

it's right that you should discharge the monitor before taking it completely apart, tho.. but that's not THAT big of a deal.

Arakon - I know MOST charge is in the CRT. But a tube IS a big capacitor! There are usually some big cans that store a lot too.

And a 40KV shock IS a big deal!!!!!! Its high current so can kill - c'mon, mains current can kill!

What I mean with "not a big deal" is that it's rather easy and safe to discharge the tube if you do it properly, and there's plenty of instructions for it on the net.

I found this helpful:
http://www.alsarcade.com/capkit.htm

I replaced the caps in my NBA Jam machine, in which I have a 1-slot (but no fourth button). It worked, but I'm glad I had some expert help in the form of a friend who'd done it before.

Hey, a word of warning--a cap kit won't hurt, but it might not necessarily solve a missing color problem. It could be the gun in the monitor or it could be a chip thing. Either way do the cap kit because they only last about a decade, but don't be too surprised if there's more to it than that. I unsuccessfully tried to figure out how to solve missing color problems on two other coin-ops and never found a solution I felt comfortable applying with my limited skills... <IMG SRC="smilies/confused.gif" border="0">

"Arakon - I know MOST charge is in the CRT."

Actually, the death-shock would come from the mains capacitor(s) near the power supply. Touching one of these is akin to sticking your finger in a mains outlet, or trying to unjam your toaster with a fork while it's plugged in.

I've taken a CRT shock before, and while my head ended up implanted in the ceiling, I was mostly all right. It's really not that bad on smaller tubes, but the larger the tube (and flyback), the more charge it will hold. If you're doing work on the neck board, you should be fine. If you're doing work on the mainboard, you ought to discharge the CRT ... easy - stick a flathead screwdriver [with plastic handle!!!] under the anode and along the surface of the CRT, and try not to jump and break things when it sparks.

To avoid the mains cap biting you, wait 10-20 minutes before doing work on the hot side of the board. The cap will leak its charge on its own. You could probably discharge it immediately with probably a few kV resistor across the pins, but I've not done this so don't take my word for it.

I'm no expert, but it sounds to me like the red gun ( of the red, green, and blue guns )on your monitor is burned out. In that case the CRT has gone bad, and a cap kit or chassis replacement won't fix it. Or, the red input wire could be loose. I also recommend discharging the monitor before ya mess with it.
And if all else fails, you could get a new monitor. There's some brand new 19" monitors right now going for $150 on eBay.

Runder's method does indeed work, and it's sort of the standard way to do it. It WILL spark so be ready. And then wait a few minutes and do it again...it will probably spark again, only less so. Repeat until no sparkage commences. <IMG SRC="smilies/smile.gif" border="0"> A friend also tapes a wire and an alligator clip to the monitor chassis when doing this as a ground--not a bad idea.