Kortek KT-2914F Horizontal Failure

[fredster]

Worked Yesterday, but not today.  The Horizontal is shrunk to 1/3 of the screen.  It's folded. I think it blew because I had too many extension cords on too many machines...

I downloaded the schematic.  Is this just one transistor? The Horizontal Output Transistor? Looking at this schematic I downloaded (and I had to download the korean fonts to read it) it's Q713? (FQP4N20?).

Am I close?  If I am, what's the NTE P/N?

Any other suggestions?

http://na.suzohapp.com/service_cente...ktxx14x_sm.pdf

[MonMotha]

Q713 (4N20) is the what drives the HOT (via pulse transformer T703), not the HOT itself.  The HOT is Q712 (2SC5584).

Also check the S correction switches (Q703, Q706, Q708 - all 19N20 type) and caps (C702, C705, C709).  The switches go bad frequently and will cause distortion and, usually, eventual failure of the HOT and other components.  Grainspain has actually reported that they sometimes catch fire.  I would remove the monitor from service until you get this fixed so that it doesn't have the opportunity to destroy itself.

The monitor has an SMPS and is free-range input, so I wouldn't expect too many extension cords to cause much in the way of problems like this, but who knows how well behaved the power supply is.

What resolution (kHz) are you running this at?

[fredster]

31K, I think. It's a new bowling game from Namco.  It's being run from a VGA port off of a ATX motherboard.  The game is on a flash drive.

It had some slight discoloration.  Like some greens where they didn't belong, etc.  I'll do the cap kit, but I think I'll replace that Q712 while I'm in there.  At least I got close in the Schematic.  It didn't give me any bars or other issues.  Just started up screwed.

What's the NTE number? Any idea?

[MonMotha]

No idea what the NTE cross is.  MCM (mcmelectronics.com) has the Matsushita 2SC5584 in stock.  Definitely check those S-correction switches.  At 31k, they matter (they're inactive at 15k), and they are the most common failure on these things.

Slight discoloration sounds like it just needs degaussed?

[lilshawn]

No idea what the NTE cross is.

NTE2533

[MonMotha]

(they're inactive at 15k)

Just checking again, and I got that backwards.  At least one correction is active at everything but 38k (800x600 SVGA).  But yeah, check those.

[fredster]

Thanks Gentlemen!  I do appreciate the info!

Yes, it had a slight discoloration in an otherwise pristine display.  A little green like it needed degaussing. Which I tried to remedy with the switch.  It helped a little, but it didn't eliminate it all.

I just got it at the auction, as I thought it would make a great Mame.  My mame is very old now, like version 7 running windows 98.  No trackball, etc.  This monitor and setup was pretty hip.  The monitor was up and read "no signal" when I bought the machine.

I got it home and it was just the video card loose in it.  I ran it for a day and moved it in my "garage arcade".  The kids played it all day.  I must have turned it on and off about 6 times that day.  When I put it in place, I plugged it in on a power strip that had 2 other older games on it.  When the little one turned on the strip, the monitor failed.  

MonMotha, I'm a kind of remove and replace guy that is Randy Fromm trained.  What is the "s-correction" swithces? Are you talking about all the transistors in the Vertical and Horizontal deflection circuits?

Lilshawn, thanks for the cross reference.  After I asked, I found the NTE online cross reference! Thanks!



 

[MonMotha]

The switches in question are Q703, Q706, Q708 - all 19N20 type MOSFETs.  That's probably FQPF, FCPF, etc. prefix.  Should be stamped on the part that's in there.  You might actually be able to sample them for free from Fairchild if they're Fairchild parts.  They're probably near some largeish high voltage (non-electrolytic) capacitors in the horizontal output area.

[ed12]

if it attatchs ?
here is the spec for them fet's
19n20 fairchild

ed

[fredster]

Ok, I got the 3 - 19N20's and a 48 piece Cap Kit from Bob Roberts.  I got it out.  This is by far the most advanced thing I have ever worked on ... wish me luck..

And if you all have any further insight, please advise.

Thanks!

[lilshawn]

And if you all have any further insight, please advise.

go ahead and remove that silicone tube and put some real heatsink grease on that vert ic (http://forum.arcadecontrols.com/index.php?topic=115534.msg1226704#msg1226704). the sink is isolated and the tab is connected to ground anyways. it will overheat eventually. best to get it while it's still good.

[fredster]

Thanks for the tip! I really appreciate it.

I'm not sure if this has ever been worked on, it looks like it.  The back of the board looks like somebody reflowed the solder in some areas.

I'm going to concentrate on the "700" parts in the monitor.

[Ken Layton]

This is what I fixed on the only one I ever worked on:

http://forum.arcadecontrols.com/index.php?topic=109681.0

[fredster]

Thanks Ken.  I always appreciate your advice!