Since moving, monitor only shows thick white line (Kaga KZ-20EN)

[danvan]

I moved overseas for three years and entrusted my baby to my best mate. I didn't get it back the way I left it. It got moved a few times and the PC was not secured, so I suspect the base of the monitor took a few hits. It was also not turned on for a few years.

You can see in this picture there is a solid white line whenever I turn her on, regardless of whether I have the PC plugged in or not.

http://www.facebook.com/photo.php?pid=1931574&l=a4163&id=626020491



I don't have a great deal of information about what's going on inside the thing. Not thinking about the thing for three years I have completely forgotten all the modifications I did to get it up and running let alone the model of monitor etc. My website outlining all of that had since been dead an buried but thankfully www.archive.org kept a backup of most of it

http://web.archive.org/web/20041013135616/www.danvan.com/Arcade/


Any help to get my sick baby back to life would be GREATLY appreciated!!!!

Thanks
Daniel


UPDATE: Monitor is Kaga KZ-20EN 19". More information in update below.

[Ummon]

Though it could be simple pot adjustment on the monitor, it could also be vertical collapse. Seen it here before. Lots on google about it. Maybe in the wiki, too.

[sarge]

You don't have any vertical deflection.  Without knowing what type of monitor you have, the only things I can suggest is if your monitor has a remote pcb contoller, make sure it is plugged in and make sure your vertical deflection coil is plugged in.

[qrz]

look for cold (poor) solder connections in the vertical citcuitry . especially the vert output ic.
the chip is notorious for developing solder cracks due to thermal cycling. excess movement may also weaken the supports on the heatsink compounding the problem...

qrz

[danvan]

Thanks guys. I will start looking your tips up on google.

Some more information. I have found the model of monitor is a Kaga KZ-20EN (revision B or D - can't make it out - and Mitsushi 510ukb22 tube) - here are some photos of the inside of the cabinet.

http://www.facebook.com/album.php?aid=92130&l=0e985&id=626020491

I have tried adjusting the vertical positions etc with minimal noticable change to the symptoms (is that the POT adjustments you refer to Ummon?). It has a remote PCB and all the connections are firmly in place. The deflection coil, which I assume is the copper coil at the base of the monitor, appears to be connected too.

The vertical circuitry is the board at the base of the monitor or the separate PCB?

I'll have a deeper dig, but please if anyone has any better ideas please let me know!

Thanks
Daniel

[qrz]

looks to be an older chassis . therefore it will likely have a transistorized vert output stage .
there is likely 2 identical to-220 case xistors on seperate heatsinks.
check all 'lytic caps near these xistors. and check resistors supplying voltage to the vert circuitry .
seeing a schematic wouild be helpful...

qrz

[Ken Layton]

You have a Nanao/Sega MC-2000-S.

Here's the likely cause of your problem (from my copyrighted repair guide):

Vertical Collapse problem:  Check resistor R416 (22 ohm fusible, half watt), vertical output transistors Q401 & Q402 (both are type 2SD1138), and capacitor C523 (originally a 47 uf @ 50 volt, but should be changed to 100 uf @ 50 volt). C523 is located inside the cage around the flyback.

[danvan]

Okay guys, thanks again for all your help thus far. Sorry it's taken me so long to get back to you, I needed to enrol a friend with a little more electronic knowledge than myself.

We have followed Ken's tips and proven the four parts he mentions to be okay.

* The  resistor R416 checked fine for 22 ohm. We resoldered just in case.

* The 2SD1138 Silicon NPN Triple Diffused transistors (http://darasemi.com/stock%20pdf/2SD1138.pdf) both checked clear using a multimeter test when removed from the board, showing ~0.8V (test: http://www.stickycarpet.com/pinx/test.html). They have now been resoldered back onto the board.

* The capacitor C523 checked okay using a multimeter tests on the contacts underneath the PCB. I have purchased a 100uf 62V capacitor to replace it if need be but (a) am not sure why I would be doing it, and (b) am concerned about the safety of doing so. It is, as you say, in the cage that appears to be the high voltage supply to the monitor. Is this safe to open up? What measures should be taken before doing so?

We have also checked a few of the resistors we believe to be in the problem area and couldn't prove any of those to be faulty. R409  (Silver, red, red, gold - 8.22 Ohm) was reading 1.4 on the multimeter, where all the others of the same colour were correctly reading 8.x ohm. We pulled it out of the circuit and it read correctly, so we resoldered it as well.

The one thing we did find was a red/rusty colour over the bottom of the PCB. It covers around 10% of the face of the board... not quite sure what it is or if it's an issue.



The final observation we have is that there is a very light but high pitch clicking sound coming from the board, we think maybe from the high voltage output.

I would appreciate any more advice you may have on this, or if you know somewhere I can find a replacement board for this.

[Ken Layton]

Replace cap C523 as I mentioned. Checking it with a multimeter doesn't work. In this application it has to be checked with a "capacitor ESR meter".

To replace it take the monitor board out of the monitor over to the workbench. Take the top cover off the flyback cage and change the capacitor. Remember that it's an electrolytic and it's polarized. Match the capacitor plus and minus leads to the same holes in the board as the one being removed. You'll need a long pair of needle nose pliers to insert the new cap (not much room in there).

[danvan]

Thanks Ken, I'll try that tomorrow. What do I need to do to disconnect it safely? I have read about dangerous levels of voltage and that cable connecting the board to the monitor seems to be the source of that. I don't want to fry myself through ignorance

Thanks
Daniel

[danvan]

Hi Ken et al,

I have made some more progress on this. But unfortunately not getting any improvement yet.

We replaced the capacitor, which happened to already be 100uf@50v anyway (http://photos-d.ak.facebook.com/photos-ak-sf2p/v191/108/31/626020491/n626020491_2615427_9544.jpg). It looked okay but we replaced it as a precaution.

Next we checked the circuit of what I am guessing is the vert and horiz circuit feeds??? This 4-wire cable from the yoke to the PCB tested 2 on red/blue and 52 on yellow/brown on the multimeter. Not sure if this is expected results, and what each controls, but I am guessing this proved two unique closed circuits.






The next thing we noticed was the board at the other end of the 4 wires, at the yoke, had come a little loose. This did not seem to cause any disconnect with the coil but we were a little worried about this.




So, thanks for the tips so far. Any pointers on where to go now?!?

Cheers
Daniel

[Ken Layton]

Yoke looks fine. While you had the chassis out, did you install a full capacitor kit? I'm assuming you did.

[Jomac]

Sorry guys always pushed for time over here in Oz ,

Problem with this chassis is C408 , it's a 10uf tantalum capacitor , don't bother checking just replace it because it will be shorted.


On a side note , all you guys should be very thankful for having Ken Layton here to help , the time and effort he puts in freely is truly amazing .

[Kevin Mullins]

Definitely glad to have Ken around for help ....... and Joey, you've been known to help out quite a bit yourself.
 

[danvan]

Thanks to all so far! I certainly would be none the wiser on this problem without you lot. I actually am starting to understand CRT technology and electronics (a little ;-) ).

So, two questions....

Ken: when you say "did you install a full capacitor kit" - I only replaced C523, nothing else.

Joey: what voltage should I get of the 10uf tantalum capacitor? I am not near the PCB at the moment, but I will stop off on my way home and grab one.

[danvan]

Dead set legend

The 10uF capacitor fixed the vertical collapse.

I am still not over the finish line yet as there is still no picture, but that is now up to me to figure out from the rest of the components.

Thanks to all, especially Ken and Joey!!!