My CTC-16XL Project. - Page 8 - Videokarma.org TV - Video

Yamamaya42 · #**106** 04-22-2019, 07:00 PM

So far, I am not finding much WAY out of tol resistor wise in the IF section. YET, i have just barely started though, did not have much time this weekend.

i may just run through the color AFC setup. sometime on it to see what happens.

I'm still a bit disturbed that the top cover was off of the IF section when I got it, and dread that someone was playing in it.
I CAN find Heathkit sweep marker generators out there, and there are books in how to make the probes and or so it says , calibrate them, but I have NEVER done something like it before. you can also find BK ones out there, but they are kind of useless w/o the probes and cables...

Rocket · #**107** 04-22-2019, 11:24 PM

Quote:

Originally Posted by Yamamaya42

So far, I am not finding much WAY out of tol resistor wise in the IF section. YET, i have just barely started though, did not have much time this weekend.

i may just run through the color AFC setup. sometime on it to see what happens.

I'm still a bit disturbed that the top cover was off of the IF section when I got it, and dread that someone was playing in it.
I CAN find Heathkit sweep marker generators out there, and there are books in how to make the probes and or so it says , calibrate them, but I have NEVER done something like it before. you can also find BK ones out there, but they are kind of useless w/o the probes and cables...

hmmmm I wonder what happened to take out so many resistors? and it sure is possible that someone did monkey with all them pots. It will be interesting to see what happens when you get all the out of value parts replaced. Perhaps, could get lucky and someone didn't screw with it too bad and it could be work.

I really need to learn as well on using a sweep gen and how to do alignment, seems like it could be a fun journey

Yamamaya42 · #**108** 04-23-2019, 10:26 AM

I'm going from pure speculation here, based on what I have looked up and seen around, and so on.
The IF alignment, sets up the general response curve of the “front end” of the TV, and the marker generator is a tool to help set that up. And when out of tune, color is prob the first thing lost, much like a FM tuner that's borked, mono works, but you just can't get MPX stereo to work, no matter how hard you try to turn the fine tuning knob...
But as I said, just an educated guess.

Electronic M · #**109** 04-23-2019, 11:02 AM

Quote:

Originally Posted by Yamamaya42

I'm going from pure speculation here, based on what I have looked up and seen around, and so on.
The IF alignment, sets up the general response curve of the “front end” of the TV, and the marker generator is a tool to help set that up. And when out of tune, color is prob the first thing lost, much like a FM tuner that's borked, mono works, but you just can't get MPX stereo to work, no matter how hard you try to turn the fine tuning knob...
But as I said, just an educated guess.

Not quite that simple. It is possible to have good sound, color, and monochrome with bad alignment they will all be at different points on the fine tuning, and if one is good the others will suck...can also loose one all together or have one or more that is never good.

Basically the sweep gen gives a flat input at all frequencies the IF can process and the marker gives narrow pips above that so you can identify key points of interest in that span... the IF changes the output level based on iti frequency response.

Yamamaya42 · #**110** 04-23-2019, 11:54 AM

What's confusing me is, when I look at manuals for marker generators for both Heathkit and BK, and see , typical color tv IF response curve with markers added, they look pretty much the same in both, but have different marker points ( mhz wise ) in the positions shown on the SAMS procedure refrence Fig, 1
I'm not sure what this means, if anything...

Electronic M · #**111** 04-23-2019, 12:21 PM

There were 2 IF frequencies in the US 21MHz(older non-UHF sets) and 44MHz (UHF, color and pretty much everything after 1960). Markers and response would vary a bit depending on the RF/IF design and the type of TV.

You can actually get a digital synthisized sin generator or an analog one and a digital frequency counter and have your own custom adjustable marker...IIRC some generators had provisions for extra crystals so the user could add fixed marker frequencies.

Video alignment is one of the few things I've never done in TV repair(but have studied to someday do). I've only had around 3 sets that genuinely needed it to function, and a few more that could have benefited from an alignment.

Audio and color you can often sort of fudge without all the gear and procedure... though some would disagree.

Rocket · #**112** 04-25-2019, 08:40 PM

Hey Yamamaya, I think my service/normal switch has been rewired, 3 of the 4 pins were cut from the switch. If you have any spare time next time your chassis is out, may I trouble you for a picture of how that switch is wired?

Yamamaya42 · #**113** 04-25-2019, 09:12 PM

https://imgur.com/byHBeuB
https://imgur.com/lF885FA

hard to make anything out but.. here

Rocket · #**114** 04-26-2019, 05:19 AM

Quote:

Originally Posted by Yamamaya42

https://imgur.com/byHBeuB
https://imgur.com/lF885FA

hard to make anything out but.. here

Thanks for the pictures!

It looks like a jumper was added between the left and middle terminal and possibly a resistor between the right and middle terminal

This is what mine looks like

Yamamaya42 · #**115** 04-26-2019, 07:34 AM

Quote:

Originally Posted by Rocket

Thanks for the pictures!

It looks like a jumper was added between the left and middle terminal and possibly a resistor between the right and middle terminal

This is what mine looks like

That make absolutely no sense whatsoever, I can't see how it can work that way... the white wire, should go to point 48 as shown on the SAMS, ( it does on mine ) and gets grounded when in service, this kills vert sweep, this is same in both 16 and 16xl.
The B side of the switch is a bit harder to understand, but looks like it is lowering the video drive on the cathodes in service position, or adjusting the voltage slightly, it is doing SOMTHING via l16, not sure, but I have no idea how your switch has been wired,,,

Yamamaya42 · #**116** 04-26-2019, 08:49 AM

From what I can see, and it's hard to tell, but it seems they someone has removed S5 entirely from the circuit , and permanently wired it into “normal” position wiring, but I can NOT understand why anyone in their right state of mind would do such a thing.

Electronic M · #**117** 04-26-2019, 09:02 AM

Radio Shack up till they vanished sold that style of switch... pretty sure they are still in production just gotta track down a source, drill out the rivets, and bolt N solder a new one in...

old_coot88 · #**118** 04-26-2019, 09:19 AM

Quote:

Originally Posted by Yamamaya42

...and permanently wired it into “normal” position wiring, but I can NOT understand why anyone in their right state of mind would do such a thing.

The switch was probably flaky and that was their fix for it. The whole purpose of the service switch was to facilitate purity and grey scale adjustments. But those can be done without the switch. Just takes a tad longer.

Yamamaya42 · #**119** 04-26-2019, 09:25 AM

https://www.mouser.com/ProductDetail...JknN1bMNhoA%3D

easy to find, they are everywhere..

Rocket · #**120** 04-26-2019, 07:32 PM

Thats great I will get that switch from mousers!

then to figure out how to get it wired right.. : /

Its hard to tell in the picture, but the switch looks burnt and the back left corner a chunk is missing of the switch. Only wire left connected on the switch is the white wire. the rest was snipped off from what I can tell, then this modification was made.

Seriously can't believe I didn't see this until recently