Re: Tech: Kortek monitor

Kortek # 1 : No dice. Still messed up. Blows F602 I need to check if R601 has a specific tolerance. Mine only reads 6.7K ohm and the specs call for 7.5. The schematics I have are for a later model of the chassis (version 1) and this is version (0). I thought I had found the problem with the big white resistor as it was reading only 220 ohm whereas my parts chassis is 300 ohms. However, it looks to be original as well. I guess I'll check the web and see if I can find an earlier schematic and manual for this chassis.


Chassis #2 with the vertical deflection issue. The screen jumps up and down and the image expands and then contracts to about a 2 inch wide image. I'm thinking its a cap right now although the monitor is brand spankin new. It still has the plastic film on the front of the monitor. Although it could have been sitting in storgage for a while. I checked all three transistors in the 300 range and all three were bad. On a whim I changed out IC401 but that didn't fix it either. I'm thinking somebody hooked up power to the sync circuits and messed this up and that is why it is not working. Guess I'll keep digging.

More to come.


Pat D.

Pat Danis in Dallas area wrote:
Man, this has been a heck of a day. Tim Peterson got me started on Korteks when he brought over a flaky one. His was a quick fix of fixing some shorted components and adjusting the fuse clips. Hopefully it will hold.

I started on mine by first replacing the cracked neck board with one from a donor chassis that had a huge crack in the main chassis. Then I did a cap kit. Then I tested it. Blew F602. Checked Hot and flyback, they are okay. Just for grins, checked Bridge rectifier, it was bad. Pulled good sub off donor chassis. Tested again powers up briefly then blows F601. Checked several resistors around it and one is a bit too far out of tolerance for my comfort level. Pulled good sub off donor chassis. I'm gonna go hook this up and see what happens. Anybody have any suggestions in case it blows again? The tube looks great on this monitor and I hate to let it sit around unused.

After I get this one going, I have another Kortek with vertical deflection issues. It really is brand new. I got it that way at a Superauction and hope to get this one fixed quickly.

Korteks are great when they work because they have the easy switch to select between positive and negative sync and you can also use the other yoke connector if you need to flip the picture. They suck because everything is jammed so close together and you need a pair of long-nosed needle nose pliers to get to anything on that chassis. That and one of the transistors in the power supply section is silked incorrectly on the board and you have to be careful how you install it.

Well, back to the hot garage. Hope somebody has some help for me. I'll report back with progress so some other poor fool working on Korteks can benefit from this. (Hopefully)

pat D.
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