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  #46  
Old 03-10-2019, 10:04 AM
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Quote:
Originally Posted by Yamamaya42 View Post
Yeah, that diode and cap are toast..
its a bit hard to find replacements using part numbers from a 50+ year old list, ( the resistor is easy )
i have picked mouser # 80-PHE450SB4220JR06 for the cap, and 625-RGP25M-E3 for the diode, i should prob replace that big cap and the little .001s on the screen pots, but they are most likely OK
These Panasonic caps are cheaper and a bit better for TV application (I use them in my resto work). https://www.mouser.com/ProductDetail...PvQRZAQNzTU%3D

This diode has a faster recovery time and is better suited for rectifying horizontal rate AC, and also has higher reverse voltage rating (Which can save your bacon if the ~4KV DC focus ever arcs over to the adjacent screens that are driven from boost). https://www.mouser.com/ProductDetail...OsoE%252B4c%3D

This is what I would buy if I were looking to replace those parts in my set.
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Last edited by Electronic M; 03-10-2019 at 10:04 AM. Reason: gramar
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  #47  
Old 03-10-2019, 01:11 PM
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total, $13 :/ its costing me more in shipping than parts

gonna replace the .001s out of safety, also getting a 0.47uF in order to do the HOT cathode current test, ( did not have one )
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  #48  
Old 03-11-2019, 08:54 AM
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While I wait for the parts ( coming tomorrow ) , there is something I've been wondering, on the schematic, (sams ) it refers to “spark gap” in a few places, like C155, but it is a normal cap, and not a spark gap capacitor, with slits in the top like I have seen before, but, they do have the leads of this cap routed in heavy stock cardboard, in what could be a spark gap configuration, is this what they mean perhaps?
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  #49  
Old 03-11-2019, 06:08 PM
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Quote:
Originally Posted by Yamamaya42 View Post
While I wait for the parts ( coming tomorrow ) , there is something I've been wondering, on the schematic, (sams ) it refers to “spark gap” in a few places, like C155, but it is a normal cap, and not a spark gap capacitor, with slits in the top like I have seen before, but, they do have the leads of this cap routed in heavy stock cardboard, in what could be a spark gap configuration, is this what they mean perhaps?
Yup!

If you ever do a late 60's-mid 70's Zenith they use two pieces of magnet wire bound together with cloth shrink wrap. Anything (or rather any two things) conductive CAN be a spark gap if you want it to be, and there were plenty of things engineers tried to make them out of.
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  #50  
Old 03-12-2019, 07:16 PM
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Boost voltage restored, I now know more than I did before.

I can almost get a pic locked in through the tuner, ( sound is OK ) pic is Horrid, and rolling horz. And there is NO COLOR via the tuner,( this may be partly due to the fact that i have 75 ohm hooked to 300, but unlikely ) this reflects the original problem with the set.
BUT if I tap in video at 1st video amp, I am able to get better sync lock and even some color lock ( a lot of barber polling)

This tells me the Original problem was most likely a messed up IF section.
I have not yet checked all the resistors in the IF yet,,, I stopped after I got a signal. I guess I have to check every one now.,,
but I'm not sure what I'll do w/o a known good Sweep Marker Generator...

Last edited by Yamamaya42; 03-12-2019 at 07:53 PM.
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  #51  
Old 03-12-2019, 08:55 PM
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Get the resistors in tolerance first...If you're lucky the alignment is fine and the only drift was resistor related.
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  #52  
Old 03-21-2019, 10:09 AM
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A bit of confusion on the horz sweep ( cathode current ) adjustment.
The sams shows all these steps to do it... https://imgur.com/iZJm7bP
however, here this guy, ( who puts up very useful videos ) , did not show those steps, or omitted them.
Where they not needed and just skipped? Or done but not shown? I'm not sure what I'm seeing here, and if I should use that as guide for mine. ( also being RCA, same output tube )
https://www.youtube.com/watch?v=uBkSfc0aq8U
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  #53  
Old 03-21-2019, 11:59 AM
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The video is showing the efficiency adjustment as an isolated procedure and assumes the other adjustments in the SAMS are nominal.

SAMS adjustments:
The first two, for "floating" H sync, are to set the H oscillator to free run at nominal frequency so the horizontal AFC and horizontal hold controls are centered and don't have to pull it one way or the other to an extreme degree. I'm not sure, but maybe being way off center could affect the horizontal drive waveform, which in turn would affect the output efficiency.

[video procedure goes here]

The measurement across R136 is actually across R146 in the SAMS schematic on ETF. This is the HV regulator cathode resistor. Caution, it is floating at about 400v. This adjustment is to check if the HV regulator range is more or less centered. If not, you are instructed to detune the efficiency coil to get more HV supply, but simultaneously not go beyond the horizontal output cathode current limit. Ideally you should be using two meters at once (if not, you need to go back and recheck the HO cathode current).

Finally, you are similarly instructed to detune the efficiency coil slightly if you see horizontal fold-over in the picture (and should recheck the HO cathode current just to be safe).
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  #54  
Old 03-21-2019, 01:00 PM
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Quote:
Originally Posted by old_tv_nut View Post
The video is showing the efficiency adjustment as an isolated procedure and assumes the other adjustments in the SAMS are nominal.

SAMS adjustments:
The first two, for "floating" H sync, are to set the H oscillator to free run at nominal frequency so the horizontal AFC and horizontal hold controls are centered and don't have to pull it one way or the other to an extreme degree. I'm not sure, but maybe being way off center could affect the horizontal drive waveform, which in turn would affect the output efficiency.

[video procedure goes here]

The measurement across R136 is actually across R146 in the SAMS schematic on ETF. This is the HV regulator cathode resistor. Caution, it is floating at about 400v. This adjustment is to check if the HV regulator range is more or less centered. If not, you are instructed to detune the efficiency coil to get more HV supply, but simultaneously not go beyond the horizontal output cathode current limit. Ideally you should be using two meters at once (if not, you need to go back and recheck the HO cathode current).

Finally, you are similarly instructed to detune the efficiency coil slightly if you see horizontal fold-over in the picture (and should recheck the HO cathode current just to be safe).
Actually, “r136” is correct for the CTC-16X series, close but not the same as CTC-16 ( sams 0818-2 vs 0736-4)
Close, but different enough to be confusing, :/
example 3rd IF on CTC-16 = 6EJ7 CTC-16X = 6JC6A, many other subtle diff.
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