a real challange?

[bandersen]

Most early TVs didn't have any retrace blanking. Ideally, they are watched in a dimly lit room and you adjust the brightness and contrast so they are not visible.

[Yamamaya42]

Originally Posted by bandersen

Most early TVs didn't have any retrace blanking. Ideally, they are watched in a dimly lit room and you adjust the brightness and contrast so they are not visible.

It's a shame that no one has come up with a blanking mod for it over the years.

[Kevin Kuehn]

Originally Posted by Yamamaya42

It's a shame that no one has come up with a blanking mod for it over the years.

Try this:

1. Place a 47k resistor between pin 11(cathode) of the CRT and ground.

2. Connect a .05uf, 630v cap from pin 3 and 4(plate) of the 6K6 vertical output
to pin 11(cathode) of the CRT.

Basically you need a positive going vert deflection pulse at the CRT cathode in order to blank the picture during vertical retrace.

[Yamamaya42]

Originally Posted by Kevin Kuehn

Try this:

1. Place a 47k resistor between pin 11(cathode) of the CRT and ground.

2. Connect a .05uf, 630v cap from pin 3 and 4(plate) of the 6K6 vertical output
to pin 11(cathode) of the CRT.

Basically you need a positive going vert deflection pulse at the CRT cathode in order to blank the picture during vertical retrace.

Tried it, not much change, yet.
as I am suspecting, this is mainly due to the diff in the test CRT ( 8YP4) and the one the set was made for, 12LP4.

And once I do have something built to put this into and mount it safely, the lines should be gone ( I hope )

Typical operation...
12LP4

Anode voltage. 11Kv
Grid #2 voltage 250v
max circuit value,
Grid #1 circuit resistance, 1.5 max meg.

8YP4
Anode voltage. 16Kv
Grid #2 voltage 400v
Grid #1 circuit resistance, 1.5 max meg.

https://frank.pocnet.net/sheets/049/1/12LP4.pdf
https://frank.pocnet.net/sheets/049/8/8YP4.pdf

The video smearing, as someone pointed out, is most likely peaking coils, but I'm STILL WAITING on the 3 that were sent from Canada on 4/15, ( 2 @ 120 uh , 1 @ 93 uh ), I wonder if they will ever show up now...

[Yamamaya42]

https://www.amazon.com/Craig-Compact.../dp/B00A71YOQI

cheap piece of crap i use for testing.


https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

the one hooked to my CTC-16 (video input ) for normal playback

[Yamamaya42]

Do ion traps go bad? ( wear out? )

reason I ask is I have 2, the original one that was with the set, that hardly seems to be magnetic at all anymore, and this NIB one I found off ebay.

https://i.ebayimg.com/00/s/MTIwMFgxN..._id=8800005007
which seems to be quite stronger

[Yamamaya42]

got the ultra cheapo Mega328 LCR-T4 tester today, only took over 3 weeks :/

Very disappointing on how it works.
does OK on CAPs and Resistors, but SUCKS on coils,

Was way WAY off by over 40% on 2 new coils 240uh and 180uh,
but what do you expect for so little $?

and the New coils I ordered never showed up.
now have try to find something else, somehow...

[JohnCT]

Originally Posted by Yamamaya42

got the ultra cheapo Mega328 LCR-T4 tester today, only took over 3 weeks :/

Very disappointing on how it works.
does OK on CAPs and Resistors, but SUCKS on coils,

Was way WAY off by over 40% on 2 new coils 240uh and 180uh,
but what do you expect for so little $?
.

Interesting. After you posted you ordered one, I checked mine for accuracy against an ordinarily very accurate Sencore Z-meter.

I found the capacitance value readings of the 328 very accurate from low values to high value electros. I found the resistance readings excellent except for values under an ohm. Strangely, using a different combinations of the three inputs gives different results on low value resistors.

But I found the accuracy of the inductors very close to what the Sencore says they are. The 328 is limited in that it doesn't read below 10uh, but other than that, it was very accurate with inductance compared to the Z-Meter

You can try calibrating the 328 tester. Short the three inputs together, then power on. It will calibrate itself and about half way through will ask you to connect a capacitor over .1uf before it finishes. I used a 4uf film capacitor when I calibrated mine and it's pretty accurate.

John

Edit: I just tried a couple more values. Low value inductors read very accurately, but I just tried a 1mH inductor, and it read 1.02mH on the Sencore, and 1.71mH on the 328. Like yours, not even close, so as far as inductors go, I'd not use this ( I didn't anyway). Resistors over an ohm and capacitors of any value are accurate. I also like how it checks transistors and also automatically identifies polarity and lead configuration.

Still, this doesn't make it totally useless on coils. If there are any other coils in the unit of identical or similar value, you can use the results on a "curve" so to speak.

.

[Electronic M]

Ion traps can loose their magnetic charge. It isn't common but does happen.

[Yamamaya42]

Trying again :/
trying to get a LCR meter that's a bit better.

also trying to get coils again from another source
perhaps these wont get lost on the way here

19-4120 - 120 uh Peaking Coil, 12k Shunt x2
however, the orig was on a 22k, meaning I will have to stick a 10k in there to keep the circuit tuned?

and again I could only get 1 93 coil :/
19-4093 - Peaking Coil, 93 uh, 10m

No shunt from what I can tell

https://imgur.com/0pAv0eh
I think I know what coil/coils are bad/ damaged, but have not been able to test/ replace yet
that 6.8 k resistor was burned to a crisp, (r141) most likely due to that .05 cap being shorted, the 10uf was WAY over 10uf, but not TOO leaky, but that paper cap had gone to crap.

[jr_tech]

Originally Posted by Yamamaya42

Trying again :/
trying to get a LCR meter that's a bit better.

I have had one of these for about 4 years.

https://www.amazon.com/5000-Handheld...8E96AREEHMW2Z2

Better than a inexpensive 328 tester... cheaper than a lab quality bench unit.

jr

[Yamamaya42]

Originally Posted by jr_tech

I have had one of these for about 4 years.

https://www.amazon.com/5000-Handheld...8E96AREEHMW2Z2

Better than a inexpensive 328 tester... cheaper than a lab quality bench unit.

jr

getting this
https://www.youtube.com/watch?v=piAhl9unCMc

[old_tv_nut]

Originally Posted by Yamamaya42

...

19-4120 - 120 uh Peaking Coil, 12k Shunt x2
however, the orig was on a 22k, meaning I will have to stick a 10k in there to keep the circuit tuned?

Peaking coils are not sharply tuned, like an IF or tuner coil. The shunt (in other words, parallel) resistor is there to damp the resonance so that you do not get too much peaking / ringing etc. A lower shunt resistor usually just means you will get less peaking and a slightly less sharp picture. You cannot improve this by adding a series resistor.

When you get the coil, if it is physically possible to disconnect one end of the resistor from the coil without mechanically destroying it, you could do that and add a shunt resistor of the specified value.
Edit: I think I misread. If you mean adding 10k in series with the 12k (not in series with the whole assembly), that would work too.


Similarly, if a peaking coil calls for a shunt resistor but the replacement has none, you can just add a resistor in parallel.

[Yamamaya42]

Originally Posted by old_tv_nut

Peaking coils are not sharply tuned, like an IF or tuner coil. The shunt (in other words, parallel) resistor is there to damp the resonance so that you do not get too much peaking / ringing etc. A lower shunt resistor usually just means you will get less peaking and a slightly less sharp picture. You cannot improve this by adding a series resistor.

When you get the coil, if it is physically possible to disconnect one end of the resistor from the coil without mechanically destroying it, you could do that and add a shunt resistor of the specified value.
Edit: I think I misread. If you mean adding 10k in series with the 12k (not in series with the whole assembly), that would work too.


Similarly, if a peaking coil calls for a shunt resistor but the replacement has none, you can just add a resistor in parallel.

the coil is lit wrapped around the resistor , i this case, and painted over with colored epoxy.
https://i.ebayimg.com/images/g/HSkAA...LGB/s-l300.jpg
this is not an exact pic, but it gets the idea across

[old_tv_nut]

Originally Posted by Yamamaya42

the coil is lit wrapped around the resistor , i this case, and painted over with colored epoxy.
https://i.ebayimg.com/images/g/HSkAA...LGB/s-l300.jpg
this is not an exact pic, but it gets the idea across

If it's not possible to disconnect one end of the resistor without destroying the coil, then you should just use it as is. Not likely to make a major difference in the result.