Need help w/ kortek 1403NA

[ahab3363]

I am repairing a merit megatouch machine that has the KT-1403NA (kortek) monitor. The game works when I use a external computer monitor, but the kortek stays black when powered up. There is a "ticking" sound coming from the flyback. Before I became a member to this site, I saw a repair log that suggested replacing the power transistor (Q402) when this happens. I replaced Q402 with a NTE 2353 and had no improvement. (no change - still ticking) It also recommends replacing C421. Problem is, this board doesn't seem to have one!? The holes on the board are there, but no cap. I know it worked before without it. Should I put one there? Should I buy a full cap kit, and hope I get lucky? Does anybody know other causes for this condition? Any help would be awesome. Ahab.

[stayouttadabunker]

Jeesh...sounds like you have a bomb ready to go off...
Usually ticking comes from a bad source of power supply and
the ticking is actually a bad solid state electronic board solenoid ticking?
You know what my dad use to do for car engines?
He used a piece of plastic stick.
He put one end on his thumb in his ear and the other end on the engine in various spots.
By the sounds going through the plastic rod - he could exactly pinpoint something
like a gear that was misaligned or a bearing that was going bad.

[Ken Layton]

I was not aware of Merit using a Kortek KT-1403NA chassis in any of their games. The only ones I've seen are the Telco/Kortek KT-1403V chassis.

Here's the schematic of the NA chassis provided by the Kortek service center:

http://www.casinotech.com/files/KT1403N_MB_Schematic.PDF

[ahab3363]

Thanks for responding guys. I will try to use the "poor mans steathascope" to find out where that tick is coming from. It really sounds like a high voltage colapse, or a small arc somewhere around or in the flyback. The schematic you guys gave me doesn't seem to show C421 either. I guess it doesn't need it. Are there some good test points where I can check the low voltages?

[ahab3363]

Well if nobody else has any other ideas, (besides putting a stick in my ear and touching it to powered up CRT board)125- I think I'll just shit-can this monitor and just buy a new one. It's a shame..... probably could have fixed it.

[Firebird]

Have you tried changing the caps in the power supply? C116, C118, C119, C121, C122, C123, C126, and C413, if that doesn't work try the flyback. If you can, post a pic of the board.

[ahab3363]

Here is a few pics.

[ahab3363]

Kortek KT-1403NA pic 2

[ahab3363]

Pic 3

[channelmaniac]

Ticking monitor is a monitor that is in shutdown for some reason.

Reason 1: Horizontal circuit can't start due to a component failure
Reason 2: There's a short circuit somewhere and the power supply is in shutdown mode

You need to check for shorted components (diodes, transistors, and other semiconductors) or bad caps first before looking for open resistors, etc.

RJ

[Firebird]

Here aree some caps that you should change
107 - 47uf, 50v
C108 - 1uf, 50v
C116 - 33uf, 200v
C118 - 100uf, 200v
C119 - 1000uf, 35v
C121 - 100uf, 200v
C122 - 1000uf, 35v
C123 - 1000uf, 16v
C126 - 470uf, 16v
C408 - 22uf, 160v
C413 - 33uf, 200v
C506 - 47uf, 50v
C508 - 100uf, 50v
Some of the values of these caps are going to be different than the ones you take out but you will have less headaches with it.

[Firebird]

One more thing, the reason you did not find the cap at C421 is because the repair logs you were looking at were for a KT-1703na, which does use that cap. But the 1403 does not.

[ahab3363]

Rock-on. I'll give the new caps a go and see what happens. Thanks very much for the info. My wife loves this machine. It keeps her quiet and off my back!

[fiddlefarter]

I know these boards very well, yes the boys are right you really need to change all the caps in the secondary of the power supply and check the horizontal output transistor this usually goes (it is mounted on the outside of the flyback), also I have found that the caps to the left of the flyback are usually faulty, and on many occasions the flyback needs replacing.
Hope this helps Sharron

[Belbtech]

Hi ahab,

I don't know if this will help you, but it may help someone out there...

Known Problem Components & the problems they cause;

C107 & C108, can cause a blackout condition.
C119 & C122, can cause a partial vertical collapse (the top half of the raster compressed into one line.)
C123, can cause horizontal tare (the signal deflects diagonally across the raster)
C126, can cause a blackout condition (also)
C408, can cause the raster to "vibrate" (AKA, "High Speed Wobble")
C420, can cause a failure to focus correctly &/or a wide raster that won't adjust to fit the screen.

D904 (on the dynamic focus board) can cause dark stripes on the left side of the raster (AKA, "competition stripes")

While these repairs are from a Kortek KT1703N, most of them will relate to other Kortek models as most manufacturers are basically lazy (if they have one product that works they will usually keep the basic design for all models).

BTW, the "ticking" could be the flyback itself.

Good luck with the repair...

God bless,
Mike><>

[mammyrat]

I've had a flyback ticking once. If I turned it on in the dark I could see the arc. Worth a try.