Donkey Kong Monitor Too Dark at the Bottom! Please Help!

[Bentendo]

Hey Folks,

This is my first time posting, so please be kind 

I purchased a restored Donkey Kong arcade machine last June. It worked fine and looked fine until my wife told me I needed to move it upstairs. I carefully lugged it up stairs to my office/game room with a couple of buddies. After we had it situtated I turned it on and noticed that the lower half of the screen was so dark I couldn't make out what was happening! I'll be honest here and admit that I don't know much about building, fixing or restoring arcades, as I'm only 24 and this is my first one. I just want my machine back in working order so I can enjoy it, but there doesn't seem to be anyone in town who can make house calls to fix an arcade machine.

I've opened up the back and fiddled with the five knobs in the back (brightness, volume, etc.) and they haven't helped the dark screen situation. I'm nervous to try anything else. Is there a potential easy fix for this? Like unplugging and plugging back in some wires or some other knobs I don't know about? I am very much a novice and I don't want to ruin my poor Donkey Kong machine completely. 

Any advice would be wonderful. Thanks in advance to anyone who posts!

- Ben, Indianapolis

[Endprodukt]

Plugging in and out a cable won't damage your cab as long as its not running. Except for the anode cap which contains high voltages your save. Try pressing all connectors into the sockets and see if that helps.

If that is not helping you need to know how to solder as it could be a cold soldering point or maybe a cap kit is needed.

[Bentendo]

Thanks for the advice. I unplugged and replugged everything I could, carefully of course. I also found two new knobs that I hadn't noticed before. When twisted the right one caused my screen bottom to come back to life! BUT it made large white streaks appear on the screen. I've included a picture to show what I mean. Not sure how to approach this now. I can turn the knob and make the streaks go away, but the bottom of my screen goes dark once more. Drat.

Not sure what to do. Just keeping playing with the knobs?

[Endprodukt]

My best advice would be stop playing with pots as they may screw your image. Or your monitor. Research is your friend. This one looks like a job for a professional.

[sandheaver]

You need a cap kit.  The darkness near the bottom is a telltale sign (as are many other common display problems you see on old monitors.)

If you know how to solder, then this will be an easy task for you.  If you don't, but you know someone that does, this will, again, be easy.

If you don't know how to solder, and you don't have a lot of money, maybe it's time to learn.

a capacitor kit will run you less than $10, but it will require that you know the exact make and model of your monitor, and that you replace every capacitor on the boards that comprise your monitor.

You can also send off the monitor and have it capped.  There are people in the Monitor/Video section of this forum who will be glad to do it.  (ah.  you're already here.)  The prices they charge will vary, as will shipping.

Replace those capacitors and your monitor will look like new (burn-in notwithstanding.)

[Bentendo]

Hrmmmm. Interesting. Glad to hear that it should be an easy fix. I do not know how to solder, but I may know someone who does.

As I have no idea what your're talking about (I'm a hopeless newbie) can you possibly link me to...

1. Where can I buy a capacitor kit

2. Where I could find the info about the make and model of my monitor

3. Where I could find a tutorial to replacing caps?

I know that's asking a lot. Thank you very much for the response.

[Endprodukt]

First off you need to know how you discharge your monitor as it can hold high voltages that can injure you badly or in the worst case kill you.

You can find the chassis model on -guess where - your chassis

For the cap kit do a quick google search.

[Endprodukt]

Oh, and tutorials are on you tube.

[sandheaver]

Look for any identifying marks on the monitor at all.  Stickers, handwriting, anything.  Take pictures and post them here if there isn't an obvious "Model No." sticker.

http://therealbobroberts.net/  He sells cap kits.  You can get them from other places, too.  Youtube has tutorials on how to do the soldering and how to handle everything.

Everyone makes a big deal about discharging monitors...  They hold less charge than a stun gun or taser, and they can only shock with full force immediately after they've been turned off.  The shocks do hurt, though, if you touch the wrong things without proper precaution, but it won't kill you unless you're very old or very young.  So, learn to discharge the monitor, certainly, and certainly do the discharging, but don't fear the monitor.  It won't kill you unless you shatter it and use a shard of glass to cut your throat open.  I don't know why everyone promotes fear so readily...

[qrz]

the problem is caused by a faulty boost cap
likely a 4.7-10uF /160- 250v cap

your pic depicts  "jail bars" .
the result of reduced voltage to the cathode drives on the CRT
(dark on LEFT side ranging to lighter on right and with vertical bars )

 note :
some adjustments may be required after "recapping" as system voltages will
be returned to "as new" levels ...

[Bentendo]

Talked to a few local arcade fellows and these seems to be my options.

- Option #1: Guy who sold me  the DK machine says if I bring it in he'll swap out the monitor for a nice new one for $150. No charge for the labor. He's about 20 minutes away

- Option #2: Guy on the other side of town says he can do it. Not highly recommended by others it seems. Not very nice and apparently takes a long time to get things done. No sure on pricing but probs around $100 (maybe more), plus I gotta get it there. He's about 30 minutes away.

- Option #3: I order a cap kit and my buddy who tinkers in electronics all the time and knows how to solder can take a whack at it. Not sure about this one, as it seems like something you'd really want to get done professionally.

I'm obviously leaning towards #1.

Thoughts?

[sandheaver]

#3 is what I'd do.

Its a trivial pursuit for anyone who knows how to wield a soldering iron.  Take old cap out, solder new one in.  Repeat for all capacitors.  Of course you must discharge the tube and take the chassis out of the monitor in the first place, then put it back in when you're done, but that's not hard, either.

How to discharge a monitor:

How to change the capacitors: then this

[Endprodukt]

As mentioned: it most likely won't kill you but I would prefer not being tazered by a chassis. Safety first.

[buffett]

and if all else fails you can send it to me and i will fix it.

check out my YouTube channel and see for yourself what i do.

https://www.youtube.com/user/buffett1978/videos?flow=grid&view=0

Peace
Buffett

[mgb]

Option 1 does sound good if you're not into fixing it yourself. $150 for a 20ez monitor in very good working shape (if it is) is pretty good. I have charged more than that for doing rebuilds in them.

The guy that is not highly recommended may be best avoided.

If your buddy does it, keep a few things in mind:
   first off the cap kit typically comes with an audio rebuild kit too. the audio board is attached to the monitor. If you don't have an annoying hum coming from your speakers, you may wanna just skip rebuilding the audio board.
  When I capkit a 20ez monitor, I also replace the B+ pot because the one on there is fragile and easily breaks. if you get your cap kit from www.therealbobroberts.net, he also carries the b+ pot.
  after doing the cap kit, the B+ must be adjusted. there are alot of resources online that show how to do this. it should be 108v when properly adjusted.
this should be done with plastic tv adjustment tools (bob roberts also carries these)
 and make sure that the monitor does not get plugged into a wall socket at all. these monitors have a 2 prong plug on them but they require an isolation transformer and this particular monitor powers on 100vac so you need to use the transformer that is in the bottom of the cabinet.

  $150 for a monitor in good shape is not bad but if you buy the cap kit, b+ pot and television adjustment set tools, you will spend under $50.
I think its also very good to have some kinda idea on how to fix these cabs because they are old and were never designed to last this long.

remember also that the monitor will need to be discharged before the boards are removed for service. this needs to be done carefully but its not the big dramatic deal that some here will make it sound to be. there is a bunch of info online on this. and DON'T touch the adjustment rings on the back end of the picture tube. these are for convergence of the guns and will drive you crazy if you try to adjust.
good luck